Functional imaging of head and neck squamous cell carcinoma with diffusion-weighted MRI and FDG PET/CT: quantitative analysis of ADC and SUV

Diagnostic Efficacy of Dynamic Maneuver in Contrast-Enhanced Computed Tomography Compared With Conventional Contrast-Enhanced Computed Tomography in Imaging the Neck Region

Introduction Dynamic contrast-enhanced computed tomography (DCE-CT) and conventional contrast-enhanced computed tomography (CE-CT) are widely used to evaluate neck lesions, including lymph node metastases, thyroid nodules, salivary gland tumors, and other soft tissue masses. DCE-CT, which captures multiple phases of contrast enhancement over time, is hypothesized to provide superior diagnostic accuracy compared to the single-phase images obtained by CE-CT due to its ability to offer dynamic information about tissue perfusion, blood volume, and vascular permeability. Methods This retrospective observational diagnostic study included 100 patients who underwent neck imaging, divided equally into DCE-CT and CE-CT groups. Patient demographics (age, gender, body mass index) and lesion characteristics (type, location, size, enhancement pattern, margins) were recorded. Diagnostic performance metrics (sensitivity, specificity, accuracy, positive predictive value, negative predictive value) were evaluated alongside inter-observer variability using the kappa statistic. Clinical impact was assessed based on changes in treatment plans and improvements in patient outcomes. The radiation dose for each modality was documented. Statistical analysis was performed using SPSS software (IBM SPSS Statistics for Windows, IBM Corp., Armonk, NY) with chi-square tests for categorical variables and t-tests for continuous variables. Results The study included 58 males and 42 females with a mean age of 55.5 years. A total of 145 lesions were detected: 75 by DCE-CT and 70 by CE-CT. DCE-CT demonstrated higher sensitivity (93.33%) and specificity (96.00%) compared to CE-CT (sensitivity 86.67%, specificity 92.00%). The accuracy of DCE-CT was 94.00% versus 88.00% for CE-CT. Inter-observer agreement was higher for DCE-CT (kappa = 0.85) compared to CE-CT (kappa = 0.80). DCE-CT led to treatment plan changes in 40% of cases and resulted in a 75% improvement in outcomes compared to 25% and 60%, respectively, for CE-CT. The mean radiation dose was slightly higher for DCE-CT (8.5 mSv) compared to CE-CT (7.0 mSv). Conclusion DCE-CT offers superior diagnostic efficacy compared to CE-CT for imaging neck lesions with enhanced sensitivity, specificity, and accuracy. Its ability to capture multiple phases of contrast enhancement allows for detailed lesion characterization and provides crucial quantitative data on tissue perfusion and blood volume. These benefits lead to more frequent improvements in patient outcomes and changes in treatment plans. Despite the slightly higher radiation dose, the diagnostic advantages of DCE-CT outweigh the disadvantages, particularly in complex cases requiring detailed lesion analysis. Further prospective studies are recommended to validate these findings and explore the broader clinical benefits of DCE-CT.

Biomechanical imaging biomarker during chemoradiotherapy predicts treatment response in head and neck squamous cell carcinoma

Objective. For response-adapted adaptive radiotherapy (R-ART), promising biomarkers are needed to predict post-radiotherapy (post-RT) responses using routine clinical information obtained during RT. In this study, a patient-specific biomechanical model (BM) of the head and neck squamous cell carcinoma (HNSCC) was proposed using the pre-RT maximum standardized uptake value (SUVmax) of18F-fluorodeoxyglucose (FDG) and tumor structural changes during RT as evaluated using computed tomography (CT). In addition, we evaluated the predictive performance of BM-driven imaging biomarkers for the treatment response of patients with HNSCC who underwent concurrent chemoradiotherapy (CCRT).Approach. Patients with histologically confirmed HNSCC treated with definitive CCRT were enrolled in this study. All patients underwent CT two times as follows: before the start of RT (pre-RT) and 3 weeks after the start of RT (mid-RT). Among these patients, 67 patients who underwent positron emission tomography/CT during the pre-RT period were included in the final analysis. The locoregional control (LC), progression-free survival (PFS), and overall survival (OS) prediction performances of whole tumor stress change (TS) between pre- and mid-RT computed using BM were assessed using univariate, multivariate, and Kaplan-Meier survival curve analyses, respectively. Furthermore, performance was compared with the pre and post-RT SUVmax, tumor volume reduction rate (TVRR) during RT, and other clinical prognostic factors.Main results. For both univariate, multivariate, and survival curve analyses, the significant prognostic factors were as follows (p< 0.05): TS and TVRR for LC; TS and pre-RT FDG-SUVmaxfor PFS; and TS only for OS. In addition, for 2 year LC, PFS, and OS prediction, TS showed a comparable predictive performance to post-RT FDG-SUVmax.Significance. BM-driven TS is an effective prognostic factor for tumor treatment response after CCRT. The proposed method can be a feasible functional imaging biomarker that can be acquired during RT using only routine clinical data and may provide useful information for decision-making during R-ART.

Reproducibility of diffusion-weighted magnetic resonance imaging in head and neck cancer assessed on a 1.5 T MR-Linac and comparison to parallel measurements on a 3 T diagnostic scanner

BACKGROUND AND PURPOSE

Before quantitative imaging biomarkers (QIBs) acquired with magnetic resonance imaging (MRI) can be used for interventional trials in radiotherapy (RT), technical validation of these QIBs is necessary. The aim of this study was to assess the reproducibility of apparent diffusion coefficient (ADC) values, derived from diffusion-weighted (DW) MRI, in head and neck cancer using a 1.5 T MR-Linac (MRL) by comparison to a 3 T diagnostic scanner (DS).

MATERIAL AND METHODS

DW-MRIs were acquired on MRL and DS for 15 head and neck cancer patients before RT and in week 2 and rigidly registered to the planning computed tomography. Mean ADC values were calculated for submandibular (SG) and parotid (PG) glands as well as target volumes (TV, gross tumor volume and lymph nodes), which were delineated based on computed tomography. Mean absolute ADC differences as well as within-subject coefficient of variation (wCV) and intraclass correlation coefficients (ICCs) were calculated for all volumes of interest.

RESULTS

A total of 23 datasets were analyzed. Mean ADC difference (DS-MRL) for SG, PG and TV resulted in 142, 254 and 93·10-6 mm2/s. wCVs/ICCs, comparing MRL and DS, were determined as 13.7 %/0.26, 24.4 %/0.23 and 16.1 %/0.73 for SG, PG and TV, respectively.

CONCLUSION

ADC values, measured on the 1.5 T MRL, showed reasonable reproducibility with an ADC underestimation in contrast to the DS. This ADC shift must be validated in further experiments and considered for future translation of QIB candidates from DS to MRL for response adaptive RT.

PET/MR Imaging in Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) can either be examined with hybrid PET/MR imaging systems or sequentially, using PET/CT and MR imaging. Regardless of the acquisition technique, the superiority of MR imaging compared to CT lies in its potential to interrogate tumor and surrounding tissues with different sequences, including perfusion and diffusion. For this reason, PET/MR imaging is preferable for the detection and assessment of locoregional residual/recurrent HNSCC after therapy. In addition, MR imaging interpretation is facilitated when combined with PET. Nevertheless, distant metastases and distant second primary tumors are detected equally well with PET/MR imaging and PET/CT.

Utility of diffusion-weighted imaging to differentiate benign and malignant solid orbital tumours

OBJECTIVE

We assessed the utility of apparent diffusion coefficients (ADCs) derived from diffusion-weighted imaging to differentiate benign and malignant orbital tumours by oculoplastic surgeons in the clinical setting and sought to validate observed ADC cut-off values.

DESIGN AND PARTICIPANTS

Retrospective review of patients with benign or malignant biopsy-confirmed orbital tumours.

METHODS

Blinded graders including 2 oculoplastic surgeons, 1 neuroradiologist, and 1 medical student located and measured orbital tumour ADCs (10-6 mm2/s) using the Region of Interest tool.

OUTCOME MEASURES

Nonradiologist measurements were compared with each other to assess reliability and with an expert neuroradiologist measurement and final pathology to assess accuracy.

RESULTS

Twenty-nine orbital tumours met inclusion criteria, consisting of 6 benign tumours and 23 malignant tumours. Mean ADC values for benign orbital tumours were 1430.59 ± 254.81 and 798.68 ± 309.12 mm2/s for malignant tumours. Our calculated optimized ADC cut-off to differentiate benign from malignant orbital tumours was 1120.84 × 10-6 mm2/s (sensitivity 1, specificity 0.9). Inter-rater reliability was excellent (intraclass correlation coefficient = 0.92; 95% CI, 0.86-0.96). Our 3 graders had a combined accuracy of 84.5% (92.3%, 92.3%, and 65.4%).

CONCLUSIONS

Our ADC cut-off of 1120.84 × 10-6 mm2/s for benign and malignant orbital tumours agrees with previously established values in literature. Without priming with instructions, training, or access to patient characteristics, most tumours were correctly classified using rapid ADC measurements. Surgeons without radiologic expertise can use the ADC tool to quickly risk stratify orbital tumours during clinic visits to guide patient expectations and further work-up.

Non-Gaussian model-based diffusion-weighted imaging of oral squamous cell carcinoma: associations with Ki-67 proliferation status

OBJECTIVES

To investigate possible associations between diffusion-weighted imaging (DWI) parameters derived from a non-Gaussian model fitting and Ki-67 status in patients with oral squamous cell carcinoma (OSCC).

METHODS

Twenty-four patients with newly diagnosed OSCC were prospectively recruited. DWI was performed using six b-values (0-2500). The diffusion-related parameters of kurtosis value (K), kurtosis-corrected diffusion coefficient (DK), diffusion heterogeneity (α), distributed diffusion coefficient (DDC), slow diffusion coefficient (Dslow), and apparent diffusion coefficient (ADC) were calculated from four diffusion fitting models. Ki-67 status was categorized as low (Ki-67 percentage score < 20%), middle (20-50%), or high (> 50%). Kruskal-Wallis tests were performed between each non-Gaussian diffusion model parameters and Ki-67 grade.

RESULTS

The Kruskal-Wallis tests revealed that multiple parameters (K, ADC, Dk, DDC and Dslow) showed statistically significant differences between the three levels of Ki-67 status (K: p = 0.020, ADC: p = 0.012, Dk: p = 0.027, DDC: p = 0.007 and Dslow: p = 0.026).

CONCLUSIONS

Several non-Gaussian diffusion model parameters and ADC values were significantly associated with Ki-67 status and have potential as promising prognostic biomarkers in patients with OSCC.

Assessing the variability and correlation between SUV and ADC parameters of head and neck cancers derived from simultaneous PET/MRI: A single-center study

OBJECTIVE

Intratumoral heterogeneity is associated with poor outcomes in head and neck cancer (HNC) patients owing to chemoradiotherapy resistance. [¹⁸ F]-FDG positron emission tomography (PET) / Magnetic Resonance Imaging (MRI) provides spatial information about tumor mass, allowing intratumor heterogeneity assessment through histogram analysis. However, variability in quantitative PET/MRI parameter measurements could influence their reliability in assessing patient prognosis. Therefore, to use standardized uptake value (SUV) and apparent diffusion coefficient (ADC) parameters for assessing tumor response, this study aimed to measure SUV and ADC's variability and assess their relationship in HNC.

METHODS

First, ADC variability was measured in an in-house diffusion phantom and in five healthy volunteers. The SUV variability was only measured with the NEMA phantom using a clinical imaging protocol. Furthermore, simultaneous PET/MRI data of 11 HNC patients were retrospectively collected from the National Cyclotron and PET center in Chulabhorn Hospital. Tumor contours were manually drawn from PET images by an experienced nuclear medicine radiologist before tumor volume segmentation. Next, SUV and ADC's histogram were used to extract statistic variables of ADC and SUV: mean, median, min, max, skewness, kurtosis, and 5^th , 10^th , 25^th , 50^th , 75^th , 90^th , and 95^th percentiles. Finally, the correlation between the statistic variables of ADC and SUV, as well as Metabolic Tumor volume and Total Lesion Glycolysis parameters was assessed using Pearson's correlation.

RESULTS

This pilot study showed that both parameters' maximum coefficient of variation was 13.9% and 9.8% in the phantom and in vivo, respectively. Furthermore, we found a strong and negative correlation between SUV_max and ADV_med (r = -0.75, P = 0.01).

CONCLUSION

The SUV and ADC obtained by simultaneous PET/MRI can be potentially used as an imaging biomarker for assessing intratumoral heterogeneity in patients with HNC. The low variability and relationship between SUV and ADC could allow multimodal prediction of tumor response in future studies.

SPECT/CT and PET/CT, related radiopharmaceuticals, and areas of application and comparison

The paper begins by identifying the key historical elements in the development of nuclear medicine imaging, focusing on the Anger camera and single photon emission computed tomography (SPECT) technologies. In this context, key reference is made to the physics of detection in Anger camera systems, especially key components such as the sodium iodide crystal, the function and performance of photomultiplier tubes, and the collimator design. It is discovered that within each component of technology, there are fundamental physical relationships that govern the performance of each component, and that overall image quality is the result of the complex interaction of all such elements. The increasing use of SPECT/CT imaging is described and illustrated with a range of typical clinical applications, which include brain, spinal, cardiac, and cancer studies. The use of CT imaging functionality allows for SPECT image correction based on compensation for absorption within tissue. Reference is also made to the basics of positron emission tomography (PET) imaging and, in particular, to the integration of PET/CT systems where the anatomy profile of the CT image is used to provide correction for photon absorption. A summary is provided of the radionuclides and radiopharmaceuticals commonly used in PET/CT imaging and a range of image studies referenced includes those of nasopharyngeal carcinoma, lung cancer investigation, brain investigation (cancer detection and dementia) and cardiac function. Reference is made to the development of "time of flight" (TOF) technology for improving of image resolution in PET/CT systems. Furthermore, SPECT/CT and PET/CT imaging systems are compared, where a key factor identified is the significantly higher number of photons detected with PET/CT technology and improved image resolution.

Repeatability of diffusion-weighted magnetic resonance imaging in head and neck cancer at a 1.5 T MR-Linac

BACKGROUND AND PURPOSE

Functional information acquired through diffusion-weighted magnetic resonance imaging (DW-MRI) may be beneficial for personalized head and neck cancer (HNC) radiotherapy. Technical validation is required before DW-MRI based radiotherapy interventions can be realized clinically. The aim of this study was to assess the repeatability of apparent diffusion coefficients (ADC) derived from DW-MRI in HNC using echo-planar imaging (EPI) on a 1.5 T MR-Linac.

MATERIAL AND METHODS

A total of eleven HNC patients underwent test/retest DW-MRI scans at least once per week during fractionated radiotherapy at the MR-Linac. An EPI DW-MRI test scan (b=0, 150, 500 s/mm²) was acquired before the start of adaptive MR-guided radiotherapy in addition to an identical retest scan after irradiation. Volumes-of-interest (VOI) were defined manually for parotid (PTs) and submandibular glands (SMs), gross tumor volume (GTV) and lymph nodes (LNs). Mean ADC was calculated for all VOI in all test/retest scans. Absolute/relative repeatability coefficients (RCs/relRCs) as well as intraclass correlation coefficients (ICCs) were determined for all VOI.

RESULTS

A total of 81 datasets were analyzed. Mean test ADC values were 1380/1416, 950/1010, 1520 and 1344·10^-6 mm²/s for left/right SM and PT, GTV and LNs, respectively. Accordingly, RC (relRC) values were determined as 271/281 (19.4/21.8%) and 138/155 (13.3/15.2%), 457 (31.3%) and 310·10^-6 mm²/s (23.5%). ICC resulted in 0.80/0.87, 0.97/0.94, 0.75 and 0.83 for left/right SM and PT, GTV and LNs, respectively.

CONCLUSION

The repeatability of ADC derived from EPI DW-MRI at the 1.5 T MR-Linac appears reasonable to be used for future biologically adapted MR-guided radiotherapy.

Correlation between Tissue Cellularity and Metabolism Represented by Diffusion-Weighted Imaging (DWI) and 18F-FDG PET/MRI in Head and Neck Cancer (HNC)

Simple Summary

We report on the correlation between the diffusion-weighted imaging (DWI) and the metabolic volume parameters derived from a PET scan, to determine the correlation between these parameters and the tumor cellularity in head and neck primary tumors. Our findings implied that there was no correlation between the information derived from the DWI and the information derived from the FDG metabolic parameters. Thus, both imaging techniques might play a complementary role in HNC diagnosis and assessment. This is significant because the treatment plan of patients with HNC should be well evaluated by using all the available diagnosis techniques, for a better understanding of how the tumor will react.

Abstract

Background: This study aimed to assess the association of 18F-Fluorodeoxyglucose positron-emission-tomography (18F-FDG/PET) and DWI imaging parameters from a primary tumor and their correlations with clinicopathological factors. Methods: We retrospectively analyzed primary tumors in 71 patients with proven HNC. Primary tumor radiological parameters: DWI and FDG, as well as pathological characteristics were analyzed. Spearman correlation coefficient was used to assess the correlation between DWI and FDG parameters, ANOVA or Kruskal–Wallis, independent sample t-test, Mann–Whitney test, and multiple regression were performed on the clinicopathological features that may affect the 18F- FDG and apparent-diffusion coefficient (ADC) of the tumor. Results: No significant correlations were observed between DWI and any of the 18F-FDG parameters (p > 0.05). SUVmax correlated with N-stages (p = 0.023), TLG and MTV correlated with T-stages (p = 0.006 and p = 0.001), and ADC correlated with tumor grades (p = 0.05). SUVmax was able to differentiate between N+ and N− groups (p = 0.004). Conclusions: Our results revealed a non-significant correlation between the FDG-PET and ADC-MR parameters. FDG-PET-based glucose metabolic and DWI-MR-derived cellularity data may represent different biological aspects of HNC.

Geometrical Comparison and Quantitative Evaluation of 18F-FDG PET/CT- and DW-MRI-Based Target Delineation Before and During Radiotherapy for Esophageal Squamous Carcinoma

Background and Purpose

This study aimed to evaluate the geometrical differences in and metabolic parameters of ¹⁸F-fluorodeoxyglucose positron emission tomography–computed tomography (¹⁸F-FDG PET-CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) performed before and during radiotherapy (RT) for patients with esophageal cancer based on the three-dimensional CT (3DCT) medium and explore whether the high signal area derived from DW-MRI can be used as a tool for an individualized definition of the volume in need of dose escalation for esophageal squamous cancer.

Materials and Methods

Thirty-two patients with esophageal squamous cancer sequentially underwent repeated 3DCT, ¹⁸F-FDG PET-CT, and enhanced MRI before the initiation of RT and after the 15th fraction. All images were fused with 3DCT images through deformable registration. The gross tumor volume (GTV) was delineated based on PET Edge on the first and second PET-CT images and defined as GTV_PETpre and GTV_PETdur, respectively. GTV_DWIpre and GTV_DWIdur were delineated on the first and second DWI and corresponding T₂-weighted MRI (T₂W-MRI)-fused images. The maximum, mean, and peak standardized uptake values (SUVs; SUV_max, SUV_mean, and SUV_peak, respectively); metabolic tumor volume (MTV); and total lesion glycolysis(TLG) and its relative changes were calculated automatically on PET. Similarly, the minimum and mean apparent diffusion coefficient (ADC; ADC_min and ADC_mean) and its relative changes were measured manually using ADC maps.

Results

The volume of GTV_CT exhibited a significant positive correlation with that of GTV_PET and GTV_DWI (both p < 0.001). Significant differences were observed in both ADCs and ¹⁸F-FDG PET metabolic parameters before and during RT (both p < 0.001). No significant correlation was observed between SUVs and ADCs before and during RT (p = 0.072–0.944) and between ∆ADCs and ∆SUVs (p = 0.238–0.854). The conformity index and degree of inclusion of GTV_PETpre to GTV_DWIpre were significantly higher than those of GTV_PETdur to GTV_DWIdur (both p < 0.001). The maximum diameter shrinkage rate (∆LD_DWI) (24%) and the tumor volume shrinkage rate (VRR_DWI) (60%) based on DW-MRI during RT were significantly greater than the corresponding PET-based ∆LD_PET (14%) and VRR_PET (41%) rates (p = 0.017 and 0.000, respectively).

Conclusion

Based on the medium of CT images, there are significant differences in spatial position, biometabolic characteristics, and the tumor shrinkage rate for GTVs derived from ¹⁸F-FDG PET-CT and DW-MRI before and during RT for esophageal squamous cancer. Further studies are needed to determine if DW-MRI will be used as tool for an individualized definition of the volume in need of dose escalation.

MR Imaging of Laryngeal and Hypopharyngeal Cancer

State-of-the-art MR imaging of the larynx and hypopharynx with high-resolution surface coils, parallel imaging techniques, and DWI has several advantages over CT for assessing submucosal tumor spread, in particular neoplastic involvement of the paraglottic space, laryngeal cartilages, and extralaryngeal soft tissues. Current diagnostic MR imaging criteria based on a combination of distinct imaging features on morphologic sequences combined with DWI allow improved discrimination between tumor, peritumoral inflammation, and fibrosis and, ultimately, an increased precision for submucosal tumor delineation, which is a key prerequisite for tailored treatment options. Multiparametric MR imaging with DWI has a higher diagnostic performance than CT.

Relationships Between DCE-MRI, DWI, and 18F-FDG PET/CT Parameters with Tumor Grade and Stage in Patients with Head and Neck Squamous Cell Carcinoma

Objectives

Properties of head and neck squamous cell carcinoma (HNSCC) such as cellularity, vascularity, and glucose metabolism interact with each other. This study aimed to investigate the associations between diffusion-weighted imaging (DWI), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and positron emission tomography/computed tomography (PET/CT) in patients with HNSCC.

Methods

Fourteen patients who were diagnosed with HNSCC were investigated using DCE-MRI, DCE, and ¹⁸fluoride-fluorodeoxyglucose PET/CT and evaluated retrospectively. Ktrans, Kep, Ve, and initial area under the curve (iAUC) parameters from DCE-MRI, ADC_max, ADC_mean, and ADCmin parameters from DWI, and maximum standardized uptake value (SUV_max), SUV_mean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) parameters from PET were obtained. Spearman's correlation coefficient was used to analyze associations between these parameters. In addition, these parameters were grouped according to tumor grade and T and N stages, and the difference between the groups was evaluated using the Mann-Whitney U test.

Results

Correlations at varying degrees were observed in the parameters investigated. ADC_mean moderately correlated with Ve (p=0.035; r=0.566). Ktrans inversely correlated with SUV_max (p=0.017; r=-0.626). iAUC inversely correlated with SUV_max, SUV_mean, TLG, and MTV (p<0.05, r≤-0.700). MTV (40% threshold) was significantly higher in T4 tumors than in T1-3 tumors (p=0.020). No significant difference was found in the grouping made according to tumor grade and N stage in terms of these parameters.

Conclusion

Tumor cellularity, vascular permeability, and glucose metabolism had significant correlations at different degrees. Furthermore, MTV may be useful in predicting T4 tumors.

Correlations between DW-MRI and 18 F-FDG PET/CT parameters in head and neck squamous cell carcinoma following definitive chemo-radiotherapy

BACKGROUND

Posttreatment diffusion-weighted magnetic resonance imaging (DW-MRI) and 18F-fluorodeoxygluocose (18 F-FDG) positron emission tomography (PET) with computed tomography (PET/CT) have potential prognostic value following chemo-radiotherapy (CRT) for head and neck squamous cell carcinoma (HNSCC). Correlations between these PET/CT (standardized uptake value or SUV) and DW-MRI (apparent diffusion coefficient or ADC) parameters have only been previously explored in the pretreatment setting.

AIM

To evaluate stage III and IV HNSCC at 12-weeks post-CRT for the correlation between SUVmax and ADC values and their interval changes from pretreatment imaging.

METHODS

Fifty-six patients (45 male, 11 female, mean age 59.9 + - 7.38) with stage 3 and 4 HNSCC patients underwent 12-week posttreatment DW-MRI and 18 F-FDG PET/CT studies in this prospective study. There were 41/56 patients in the cohort with human papilloma virus-related oropharyngeal cancer (HPV OPC). DW-MRI (ADCmax and ADCmin) and 18 F-FDG PET/CT (SUVmax and SUVmax ratio to liver) parameters were measured at the site of primary tumors (n = 48) and the largest lymph nodes (n = 52). Kendall's tau evaluated the correlation between DW-MRI and 18 F-FDG PET/CT parameters. Mann-Whitney test compared the post-CRT PET/CT and DW-MRI parameters between those participants with and without 2-year disease-free survival (DFS).

RESULTS

There was no correlation between DW-MRI and 18 F-FDG PET/CT parameters on 12-week posttreatment imaging (P = .455-.794; tau = -0.075-0.25) or their interval changes from pretreatment to 12-week posttreatment imaging (P = .1-.946; tau = -0.194-0.044). The primary tumor ADCmean (P = .03) and the interval change in nodal ADCmin (P = .05) predicted 2-year DFS but none of the 18 F-FDG PET/CT parameters were associated with 2-year DFS.

CONCLUSIONS

There is no correlation between the quantitative DWI-MRI and 18 F-FDG PET/CT parameters derived from 12-week post-CRT studies. These parameters may be independent biomarkers however in this HPV OPC dominant cohort, only selected ADC parameters demonstrated prognostic significance. Study was prospectively registered at http://www.controlled-trials.com/ISRCTN58327080.

Correlation between 18F-FDG PET/CT and diffusion-weighted MRI parameters in head and neck squamous cell carcinoma at baseline and after chemo-radiotherapy. A retrospective single institutional study

OBJECTIVES

The relationship between glucose metabolism and tumor cellularity before chemo-radiotherapy in patients with head and neck squamous cell carcinoma (SCC) has never been compared with that of patients evaluated after treatment. This retrospective study analyzed the correlation between glucose metabolism parameters expressed by standardized uptake value (SUV) derived from 18F-fluorodeoxyglucose (18F-FDG) PET/CT and cellularity tumor parameters expressed by apparent diffusion coefficients (ADC) derived from diffusion-weighted (DW) MRI in untreated and treated patients with head and neck SCC.

METHODS

In 19 patients with no previous exposure to any treatment and 17 different chemo-radiotreated patients with head and neck SCC, we correlated the semi-quantitative uptake values (SUVmax, SUVpeak, and SUVmean) with the ADC functional parameters (ADCmin, ADCmean) including the standard deviation of ADC values (ADCsd).

RESULTS

No significant correlation was found between glucose metabolism parameters and ADCmin or ADCmean in untreated and treated patient groups. However, in untreated patients, significant inverse correlations were found between ADCsd and SUVmax (P = 0.039, r = -0.476), SUVpeak (P = 0.003, r = -0.652) and SUVmean (P = 0.039, r = -0.477). Analyses after chemo-radiotherapy in 17 patients showed no significant correlation between glucose metabolism parameters and DW MRI values, excluding a persistent significant (but lower intensity) inverse correlation between SUVpeak and ADCsd (P = 0.033, r = -0.519).

CONCLUSIONS

The demonstrated relationships suggest complex interactions especially between metabolic activity and heterogeneity of tumoral tissue, which might play a complementary role in the assessment of head and neck SCC.

TRIAL DATE OF REGISTRATION AND REGISTRATION NUMBER

Our retrospective study was registered on April 9th, 2020 by the Ethics Committee of the Coordinating Center "Area Vasta Nord Ovest" (CEAVNO) with Registration Number CEAVNO09042020.

Apparent diffusion coefficient agreement and reliability using different region of interest methods for the evaluation of head and neck cancer post chemo-radiotherapy

Objectives:

Post chemoradiotherapy (CRT) interval changes in apparent diffusion coefficient (ADC) have prognostic value in head and neck squamous cell cancer (HNSCC). The impact of using different region of interest (ROI) methods on interobserver agreement and their ability to reliably detect the changes in the ADC values was assessed.

Methods:

Following ethical approval, 25 patients (mean age 59.5 years, 21 male) with stage 3–4 HNSCC undergoing CRT were recruited for this prospective cohort study. Diffusion weighted MRI (DW-MRI) was performed pre-treatment and at 6 and 12 weeks following CRT. Two radiologists independently delineated ROIs using whole volume (ROI_v), largest area (ROI_a) or representative area (ROI_r) methods at primary tumour (n = 22) and largest nodal (n = 24) locations and recorded the ADC_mean. When no clear focus of increased DWI signal was evident at follow-up, a standardised ROI was placed (non-measurable or NM). Bland-Altman plots and interclass correlation coefficient (ICC) were assessed. Paired t-tests evaluated interval changes in pre- and post-treatment ADC_mean at each location, which were compared to the smallest detectable difference (SDD).

Results:

Excellent agreement was obtained for all ROI methods at pre-treatment (ICC 0.94–0.98) and 6-week post-treatment (ICC 0.94–0.98). At 12-week post-treatment, agreement was excellent (ICC 0.91–0.94) apart from ROI_r (ICC 0.86) and the NM nodal disease (ICC 0.87). There were significant interval increases in ADC_mean between pre-treatment and post-treatment studies, which were greater than the SDD for all ROIs.

Conclusions:

ADC_mean values can be reproducibly obtained in HNSCC using the different ROI techniques on pre- and post-CRT MRI, and this reliably detects the interval changes.

Comparison of reduced field-of-view diffusion-weighted imaging (DWI) and conventional DWI techniques in the assessment of Cervical carcinoma at 3.0T: Image quality and FIGO staging

OBJECTIVE

To evaluate imaging quality (IQ) and International Federation of Gynecology and Obstetrics (FIGO) staging of reduced field-of-view (r-FOV) diffusion-weighted imaging (DWI) in cervical carcinoma (CC).

MATERIALS AND METHODS

Sixty patients with pathologically proven CC who underwent both pre-treatment r-FOV DWI and full field-of-view (f-FOV) DWI on a 3.0T MRI scanner were retrospectively reviewed. The subjective qualitative image scores were compared using the Wilcoxon signed-rank test. Objective quality values and apparent diffusion coefficient (ADC) were estimated by paired t-test or Wilcoxon signed-rank test for the two DWI sequences according to Normality test. Spearman rank correlation analysis was used to evaluate the relationship between pathological results and mean ADC value.

RESULTS

The subjective IQ scores for r-FOV DWI were significantly higher than those for f-FOV DWI (P < 0.001). Similarly, the contrast-to-noise (CNR) value of r-FOV DWI was superior to that of f-FOV DWI (10.30 ± 3.676, 8.91 ± 3.008, P = 0.021). However, the signal-to-noise ratio (SNR) value of r-FOV DWI was considerably lower than that of f-FOV DWI (27.80 ± 6.056, 33.67 ± 7.833, P＜0.001). No significant difference was found between mean ADC values of f-FOV DWI and r-FOV DWI. There was a significant tendency for a negative correlation between the ADC values and FIGO stages of CC for both two sequences (r=-0. 436, P＜0.01; r=-0.470, P＜0.01, respectively).

CONCLUSIONS

The rFOV DWI sequence provided significantly better IQ and lesion conspicuity than the fFOV DWI sequence. In addition, rFOV sequences can be used in evaluation of FIGO staging of cervical cancer.

PET/MR in Head and Neck Cancer - An Update

In academic centers, PET/MR has taken the road to clinical nuclear medicine in the past 6 years since the last review on its applications in head and neck cancer patients in this journal. Meanwhile, older sequential PET + MR machines have largely vanished from clinical sites, being replaced by integrated simultaneous PET/MR scanners. Evidence from several studies suggests that PET/MR overall performs equally well as PET/CT in the staging and restaging of head and neck cancer and in radiation therapy planning. PET/MR appears to offer advantages in the characterization and prognostication of head and neck malignancies through multiparametric imaging, which demands an exact preparation and validation of imaging modalities, however. The majority of available clinical PET/MR studies today covers FDG imaging of squamous cell carcinoma arising from a broad spectrum of locations in the upper aerodigestive tract. In the future, specific PET/MR studies are desired that address specific histopathological tumor entities, nonepithelial malignancies, such as major salivary gland tumors, squamous cell carcinomas arising in specific locations, and malignancies imaged with non-FDG radiotracers. With the advent of digital PET/CT scanners, PET/MR is expected to partake in future technical developments, such as novel iterative reconstruction techniques and deviceless motion correction for respiration and gross movement in the head and neck region. Owing to the still comparably high costs of PET/MR scanners and facility requirements on the one hand, and the concentration of multidisciplinary head and neck cancer treatment mainly at academic centers on the other hand, a more widespread use of this imaging modality outside major hospitals is currently limited.

Diagnostic Accuracy and Confidence of [18F] FDG PET/MRI in comparison with PET or MRI alone in Head and Neck Cancer

The usefulness of PET/MRI in head and neck malignancy has not been fully elucidated. The purpose of our study was to evaluate the diagnostic accuracy and confidence of PET/MRI in comparison with PET or MRI alone. This study included 73 consecutive patients who underwent [18F] FDG PET/MRI in head and neck under the suspicion of malignancy. A neuroradiologist and a nuclear medicine specialist reviewed MRI and PET images, respectively and independently, followed by a consensus review of PET/MRI one month later. For 134 lesions, accuracy and confidence were compared among PET, MRI, and PET/MRI. For lesion base, PET/MRI had a sensitivity of 85.7%, a specificity of 89.1%, a PPV of 89.6%, a negative predictive value of 85.1%, and an accuracy of 87.3%. AUCs of PET/MRI per lesion (0.926) and per patient (0.934) for diagnosing malignancy were higher than PET (0.847 and 0.747, respectively) or MRI (0.836 and 0.798, respectively) alone (P < 0.05). More than 80% of the cases (111/134) showed diagnostic concordance between PET and MRI. PPV of PET/MRI was higher in malignant concordant cases (93.2%, 55/59) than in discordant cases (62.5%, 5/8) (p = 0.040). Confident scoring rate in malignant concordant cases was higher on PET/MRI (96.6%, 57/59) than on MRI (76.3%, 45/59) (p = 0.003). In conclusion, compared with PET or MRI alone, PET/MRI presents better diagnostic performance in accuracy and confidence for diagnosis of malignancy. PET/MRI is useful in patients with head and neck cancer.

Correlation between apparent diffusion coefficients and metabolic parameters in hypopharyngeal squamous cell carcinoma: A prospective study with integrated PET/MRI

PURPOSE

Apparent diffusion coefficients (ADCs) derived from diffusion-weighted magnetic resonance imaging (DW-MRI) and metabolic parameters derived from ¹⁸F-FDG positron emission tomography (PET) are promising prognostic indicators for head and neck squamous cell carcinoma (SCC). However, the relationship between them remains unclear. This study aimed to investigate the relationship between ADCs and metabolic parameters in hypopharyngeal SCC (HSCC) using integrated PET/MRI.

MATERIALS AND METHODS

Twenty-seven patients with biopsy-proven HSCC underwent integrated ¹⁸F-FDG neck PET/MRI. ADCs of HSCC, including the mean and minimum ADC values (ADC_mean and ADC_min), were measured manually on ADC maps. Metabolic parameters of HSCC, including maximum and mean standardized uptake values (SUV_max and SUV_mean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were calculated automatically on PET images. Spearman correlation coefficients were used to assess the relationships between ADCs and metabolic parameters in HSCC tumors as well as in tumor groups with different histological grading, clinical staging, and anatomical subsites. P values < 0.05 were considered statistically significant.

RESULTS

No significant correlation was observed between ADCs and ¹⁸F-FDG PET metabolic parameters in the entire cohort, except for a significant inverse correlation between ADC_mean and MTV (r = -0.556, P = 0.003). Furthermore, a significant inverse correlation was observed between ADC_mean and MTV of HSCC in the moderately to well differentiated group (r_ADCmean/MTV = -0.692, P = 0.006), stage III group (r_ADCmean/MTV = -0.758, P = 0.003), and pyriform sinus group (r_ADCmean/MTV = -0.665, P = 0.007), whereas no significant correlation was observed in the poorly differentiated group, stage IV group, or non-pyriform sinus group.

CONCLUSIONS

Inverse correlation between ADC_mean and MTV in the HSCC population was observed and the correlativity depended on histological grading, clinical staging, and anatomical subsites of HSCC.

Multiparametric positron emission tomography/magnetic resonance imaging in nasopharyngeal carcinoma: Correlations between magnetic resonance imaging functional parameters and 18F-fluorodeoxyglucose positron emission tomography imaging biomarkers and their predictive value for treatment failure

Objectives:

The clinical significance of positron emission tomography/magnetic resonance imaging (PET/MRI) functional parameters in nasopharyngealcarcinoma (NPC) remains unclear. The purpose of this prospective study was two-fold: (1) to investigate the associations between simultaneously acquired PET/MRI perfusion, diffusion, and glucose metabolism parameters in patients with NPC and (2) to analyze their predictive value with respect to treatment failure.

Materials and Methods:

We enrolled 85 patients with primary NPC who simultaneously underwent¹⁸F-fluorodeoxyglucose PET/CT and PET/MRI before definitive treatment. The following variables were determined: (1) functional parameters from the MRI component, including perfusion values (K^trans,k_ep,v_e, and initial area under the enhancement curve) and apparent diffusion coefficient (ADC) values, and (2) PET parameters, including metabolic tumor volume (MTV). The reciprocal interrelationships between these parameters and their correlations with treatment failure were examined.

Results:

We observed significant negative associations between K^trans and ADC (r = −0.215, P = 0.049) as well as between v_e and ADC (r = −0.22, P = 0.04). Correlations between PET and MRI functional parameters were not statistically significant. Treatment failures were observed in 21.2% of patients without distant metastases. Multivariate analysis identified v_e as a significant independent predictor for treatment failure (P = 0.022), whereas MTV showed a borderline significance (P = 0.095). Patients in whom both v_e and MTV values were increased had a significantly higher rate of treatment failure (62.5%) than those with either one (21.9%) or no (7.7%) increased parameter (P = 0.004).

Conclusion:

Correlation analyses revealed complex interrelationships among PET and MRI indices measured in patients with NPC. These parameters may have a complementary role in predicting treatment failure in this clinical setting.

Diagnostic Capabilities of MRI Versus 18F FDG PET-CT in Postoperative Patients with Thyroglobulin Positive, 131I-negative Local Recurrent or Metastatic Thyroid Cancer

BACKGROUND

The detection of recurrence or metastasis might be challenging in patients, who underwent total thyroidectomy and radioactive iodine therapy for Differentiated Thyroid Carcinoma (DTC), with increased serum Thyroglobulin (Tg) levels and negative 131I whole body scan (131I-WBS) results.

AIMS

The purpose of this study was to compare the ability of Magnetic Resonance Imaging (MRI) and 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F FDG PET-CT) to detect recurrence or cervical and upper mediastinal metastases in postoperative DTC patients who had negative 131I-WBS despite elevated serum Tg levels.

STUDY DESIGN

This study has a retrospective study design.

METHODS

We evaluated cervical and upper mediastinal MRI and 18F FDG PET-CT of 32 postoperative patients with DTC (26 patients with papillary thyroid carcinoma and 6 patients with follicular thyroid carcinoma).

RESULTS

We evaluated 44 lesions in 32 patients. For all lesions, the Positive Predictive Value, (PPV) Negative Predictive Value (NPV), sensitivity, specificity, and accuracy of MRI were 81.4%, 76.4%, 84.6%, 72.2%, and 79.5% respectively. The PPV, NPV, sensitivity, specificity, and accuracy of 18F FDG PET-CT were 100.0%, 85.7%, 88.4%, 100.0%, and 93.1%, respectively.

CONCLUSION

Although we could not replace 18F FDG PET-CT, MRI might be used as an adjunct to 18F FDG PET-CT for the evaluation of recurrent or cervical and upper mediastinal metastatic thyroid cancers; however, MRI is inadequate for the detection of metastases in small lymph nodes.

Preliminary clinical results for PET/MR compared with PET/CT in patients with nasopharyngeal carcinoma

The present study aimed to assess the performance of positron emission tomography-magnetic resonance imaging (PET/MR) for the visualization and characterization of lesions. In addition, the present study investigated whether the apparent diffusion coefficient (ADC) and intravoxel incoherent motion parameters exhibited any significant correlation with standardized uptake values (SUV) in patients with nasopharyngeal carcinoma (NPC). A total of 35 patients with NPC underwent whole body PET-computed tomography (CT) and head and neck MR imaging (MRI) scans using the PET/CT-MRI system. Image quality, lesion conspicuity and the diagnostic confidence of PET/CT, T1 weighted (T1w) PET/MR and T2w PET/MR imaging were assessed. The true diffusion coefficient (D), the pseudo-diffusion coefficient or diffusion within the microcirculation (D*), and the perfusion fraction or the contribution of water moving in the capillaries (f), and ADC, were calculated. The correlation between the ADC, D*, D and f values and the SUV were analyzed using Pearson's correlation analysis. Similar image quality was obtained using PET/CT, T1w PET/MR and T2w PET/MR imaging. However, the T1w PET/MR and T2w PET/MR imaging were more effective than PET/CT in analyzing the lesion conspicuity of the primary tumors and lymph nodes. In addition, T2w PET/MR imaging was more efficient than T1w PET/MR imaging in analyzing primary tumors and lymph nodes. Pearson's correlation analysis showed no significant correlation between the SUV and ADC, and D*, D and f values in NPC. The present results suggested that the application of PET/MR is feasible and could serve as a reliable alternative to PET/CT, while SUV and ADC, D*, D and f values were identified as independent biomarkers in NPC.

Evaluation of quantitative imaging parameters in head and neck squamous cell carcinoma

BACKGROUND

Functional imaging such as 18F-fluoro-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT), 18F-fluoro-misonidazole (F-MISO)-PET/CT, and diffusion-weighted magnetic resonance imaging (DW-MRI) can assess complex biological phenomena in tumors reflecting underlying disease biology. The aim of this prospective observational study was to correlate quantitative imaging parameters derived from pre-treatment biological imaging such as FDG-PET/CT, F-MISO-PET/CT, and DW-MRI with each other andì with clinical outcomes in patients with head and neck squamous cell carcinoma (HNSCC) treated with definitive radio(chemo)therapy.

METHODS

Twenty patients with pharyngo-laryngeal cancers underwent pre-treatment biological imaging. Gross tumor volume (GTV) was delineated on axial planning CT (GTVCT). Quantitative FDG-PET/CT parameters included maximum, mean, minimum standardized uptake values (SUVmax-FDG, SUVmean-FDG, SUVmin-FDG); metabolic tumor volume (MTV); and total lesion glycolysis (TLG). F-MISO-PET/CT parameters included hypoxic tumor volume (HTV); maximum, mean, minimum SUV; and fractional hypoxic volume (FHV). Mean apparent diffusion coefficient (ADCmean) was derived from DW-MRI.

RESULTS

There was moderately strong positive correlation (r=0.616, p=0.005) between GTVCT and MTV. HTV derived from F-MISO-PET/CT at 3-hours (HTV3hrs-F-MISO) showed strong positive correlation with GTVCT (r=0.753, p<0.0001) and MTV (r=0.796, p<0.0001) respectively. ADCmean showed strong positive correlations with SUVmean-5hrs-F-MISO (r=0.713, p=0.021) and SUVmin-5hrs-FMISO (r=0.731, p=0.016) respectively. A moderate negative correlation (r=-0.500, p=0.049) was observed between ADCmean and MTV. At a median follow up of 44 months, the 5-year Kaplan-Meier estimates of loco-regional control, disease-free survival, and overall survival were 53%, 43%, and 40% respectively. Larger volume of primary tumor (GTVCT>22cc and MTV>7.9cc) and increasing hypoxia (HTV3hr-F-MSO>4.9cc) were associated with worse outcomes.

CONCLUSIONS

Functional imaging represents an attractive and non-invasive modality to assess complex biological phenomena in solid tumors. Larger tumor volume and increasing hypoxia emerged as putative prognostic imaging biomarkers in HNSCC.

Improved Assessment of Middle Ear Recurrent Cholesteatomas Using a Fusion of Conventional CT and Non-EPI-DWI MRI

BACKGROUND AND PURPOSE

Recurrent middle ear cholesteatomas are commonly preoperatively assessed using MR imaging (non-EPI-DWI) and CT. Both modalities are used with the aim of distinguishing scar tissue from cholesteatoma and determining the extent of bone erosions. Inflammation and scar tissue associated with the lesions might hamper a proper delineation of the corresponding extensions on CT images. Using surgical findings as the criterion standard, we assessed the recurrent middle ear cholesteatoma extent using either uncoregistered or fused CT-MR imaging datasets and determined the corresponding accuracy and repeatability.

MATERIALS AND METHODS

Twenty consecutive patients with suspected recurrent middle ear cholesteatoma and preoperative CT-MR imaging datasets were prospectively included. A double-blind assessment and coregistration of the recurrent middle ear cholesteatoma extent and manual delineation of 18 presumed recurrent middle ear cholesteatomas were performed by 2 radiologists and compared with the criterion standard. "Reliability score" was defined to qualify radiologists' confidence. For each volume, segmentation repeatability was assessed on the basis of intraclass correlation coefficient and overlap indices.

RESULTS

For the whole set of patients, recurrent middle ear cholesteatoma was further supported by surgical results. Two lesions were excluded from the analysis, given that MR imaging did not show a restricted diffusion. Lesions were accurately localized using the fused datasets, whereas significantly fewer lesions (85%) were correctly localized using uncoregistered images. Reliability scores were larger for fused datasets. Segmentation repeatability showed an almost perfect intraclass correlation coefficient regarding volumes, while overlaps were significantly lower in uncoregistered (52%) compared with fused (60%, P < .001) datasets.

CONCLUSIONS

The use of coregistered CT-MR images significantly improved the assessment of recurrent middle ear cholesteatoma with a greater accuracy and better reliability and repeatability.

Relationships between histogram analysis of ADC values and complex 18F-FDG-PET parameters in head and neck squamous cell carcinoma

Purpose

Histogram analysis is an emergent imaging technique to further analyze radiological images and to obtain imaging biomarker. In head and neck cancer, MRI and PET are routinely used in clinical practice. The aim of this study was to analyze associations between histogram based ADC parameters and complex FDG-PET derived parameters in head and neck squamous cell carcinoma (HNSCC).

Methods

34 patients (26% female, mean age, 56.7 ± 10.2 years) with primary HNSCC were prospectively included into the study. ADC histogram parameters were calculated by inhouse made matlab software using a whole lesion measurement. For each tumor, maximum and mean standardized uptake values (SUVmax, SUVmean), Total Lesion Glycolysis (TLG) and Metabolic Tumor Volume (MTV) were determined on PET-images. Spearman's correlation coefficient (ρ) was used to analyze associations between investigated parameters. Benjamini-Hochberg correction was used to adjust for multiple testing. Mann-Whitney test was used for group discrimination. P-values < 0.05 were taken to indicate statistical significance.

Results

The correlation analysis in the whole tumor group revealed a statistically significant correlation between entropy and MTV as well as TLG (ρ = 0.67, P<0.0001 and ρ = 0.61, P = 0.0002 respectively).

There were statistically significant differences between T1/2 and T3/4 tumors in the following parameters: entropy (2.07 ± 0.36 vs 2.61 ± 0.43, P = 0.007), SUVmax (10.79 ± 4.13 vs 17.93 ± 5.89, P = 0.007), SUVmean (6.39 ± 2.48 vs 9.81 ± 4.49, P = 0.01), SUVmin (4.09 ± 1.57 vs 6.34 ± 2.59, P = 0.03), MTV (9.50 ± 7.92 vs 20.36 ± 13.30, P = 0.02), TGU (55.97 ± 39.09 vs 212.3 ± 186.3, P = 0.002).

Conclusion

This study showed that entropy derived from ADC maps is strongly associated with MTV and TLG in HNSCC. Entropy, SUVmax, SUVmean, TLG and MTV were statistically significant higher in T3/4 tumors in comparison to T1/2 carcinomas.

The interobserver agreement in the detection of recurrent HNSCC using MRI including diffusion weighted MRI

INTRODUCTION

For the detection of local recurrences of head and neck squamous cell carcinomas (HNSCC) after (chemo)radiation, diagnostic imaging is generally performed. Diffusion weighted magnetic resonance imaging (DW-MRI) has been proven to be able to adequately diagnose the presence of cancer. However evaluation of DW-MR images for recurrences is difficult and could be subject to individual interpretation.

AIM

To determine the interobserver agreement, intraobserver agreement and influence of experience of radiologists in the assessment of DW-MRI in patients clinically suspected of local recurrent HNSCC after (chemo)radiation.

METHODS

Ten experienced head and neck radiologists assessed follow-up MRI including DW-MRI series of 10 patients for the existence of local recurrence on a two point decision scale (local recurrence or local control). Patients were clinically suspected for a recurrence of laryngeal (n = 3), hypopharyngeal (n = 3) or oropharyngeal (n = 4) cancer after (chemo)radiation with curative intent. Fleiss' and Cohen's Kappa were used to determine interobserver agreement and intraobserver agreement, respectively.

RESULTS

Interobserver agreement was κ = 0.55. Intraobserver agreement was κ = 0.80. Prior experience within the field of radiology and with DW-MRI had no significant influence on the scoring.

CONCLUSION

For the assessment of HNSCC recurrence after (chemo)radiation by DW-MRI, moderate interobserver agreement and substantial intraobserver agreement was found.

Correlation of the apparent diffusion coefficient and the standardized uptake value in neoplastic lesions: a meta-analysis

OBJECTIVE

Diffusion-weighted imaging and fluorine-18-fluorodeoxyglucose PET are increasingly being recognized as feasible oncological techniques. The apparent diffusion coefficient (ADC) measured by diffusion-weighted imaging and the standardized uptake value (SUV) from fluorine-18-fluorodeoxyglucose PET have similar clinical applications. The aim of this study was to assess the correlation between these two parameters in various cancers.

MATERIALS AND METHODS

Several major databases were searched for eligible studies. The correlation coefficient (ρ) values were pooled in a random-effects model. Begg's test was used to analyze the existence of publication bias and the sources of heterogeneity were explored in subgroup analyses on the basis of study design, diagnostic method, scanning modality, and tumor type.

RESULTS

Thirty-five articles were accepted. The pooled ρ value of all of the accepted studies was -0.30 (95% confidence interval: -0.33 to -0.27), and notable heterogeneity was present (I=69.4%, P<0.001), which indicated a relatively weak negative correlation. The pooled ρ values were -0.26, -0.33, -0.32, and -0.33 for the SUVmax/ADCmean, SUVmax/ADCmin, SUVmean/ADCmean, and SUVmean/ADCmin relationships, respectively. The study design and diagnostic method were potential sources of heterogeneity. Lung cancer showed a stronger correlation (ρ=-0.42) than head and neck cancer (ρ=-0.27), cervical cancer (ρ=-0.21), and breast cancer (ρ=-0.23). A Begg's test indicated no significant publication bias among the accepted studies (P>0.05).

CONCLUSION

The two functional parameters of ADC and SUV showed a very weak inverse correlation, which may contribute toward a sophisticated characterization of tumor biology. However, the findings require further validation with trials with large samples and different tumor types.

Crossed cerebellar hyperperfusion in patients with seizure-related cerebral cortical lesions: an evaluation with arterial spin labelling perfusion MR imaging

PURPOSE

Crossed cerebellar (CC) diaschisis refers to a decrease in cerebellar perfusion in the presence of contralateral supratentorial lesions. Most of the previous studies have examined stroke patients. In contrast to strokes, seizure-related cerebral cortical lesions (SCCLs) usually show hyperperfusion, and therefore, cerebellar perfusion patterns are expected to be different from those of strokes. With arterial spin labelling (ASL), we evaluated the cerebellar perfusion status in patients with SCCLs.

MATERIALS AND METHODS

Using a search of the recent database over the last 31 months, 26 patients were enrolled in this study. The inclusion criteria were as follows: (1) a history of seizures, (2) MR examination taken within 24 h from the last seizure, (3) the presence of SCCLs on T2/FLAIR or DWI, (4) hyperperfusion in the corresponding areas of SCCLs on ASL, and (5) no structural abnormality in the cerebellum. The perfusion status in the contralateral cerebellum was evaluated and categorized as hyper-, iso- and hypoperfusion. The asymmetric index (AI) of cerebellar perfusion was calculated by ROI measurement of the signal intensity on ASL.

RESULTS

The mean time between the last seizure and MR examinations was 5 h 30 min. CC hyperperfusion was observed in 17 patients (65.4%), hypoperfusion in 7 (26.9%) and isoperfusion in 2 (7.7%). Regarding the location of SCCLs, CC hyperperfusion was more frequent (71.4 vs. 58.3%), and the mean AI was higher (42.0 vs. 11.5) when the lesion involved the frontal lobe.

CONCLUSIONS

In patients with SCCLs, CC hyperperfusion occurred more often than hypo- and isoperfusion, especially when the lesions involved the frontal lobe.

18F-FDG PET/CT in immunocompetent patients with primary central nervous system lymphoma: Differentiation from glioblastoma and correlation with DWI

OBJECTIVES

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is useful for the detection of cancerous lesions, and FDG uptake is related to the apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) of extracranial tumors. The purpose of our study was to investigate the ability of FDG PET/CT in distinguishing primary central nervous system lymphoma (PCNSL) from glioblastoma multiforme (GBM) and to explore the relationship between ¹⁸F-FDG uptake and the ADC in patients with PCNSL.

METHODS

We reviewed 92 patients (40 with PCNSL and 52 with GBM) who underwent FDG PET/CT scans at disease onset. The maximum standardized uptake value (SUVmax), tumor to normal contralateral cortex activity (T/N) ratio, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of tumor lesions were calculated. Receiver operating characteristic (ROC) curves were generated to determine the diagnostic performance for FDG PET-related parameters to differentiate PCNSL from GBM. Twenty-eight patients with PCNSL (with 34 lesions) also underwent diffusion-weighted imaging. Pearson's correlation analysis was used to assess the relation between SUV- and ADC-derived parameters.

RESULTS

The SUVmax, T/N ratio, SUVmean, and TLG values were significantly higher in PCNSL than in GBM. Comparative ROC analysis indicated that the SUVmax had a greater area under the curve (AUC) of 0.910 than the T/N ratio (0.905, P = .85), SUVmean (0.836, P = .0006), or TLG (0.641, P < 0.0001). The T/N ratio had the highest specificity (94.23%) for differentiating PCNSL from GBM, while the SUVmax had the most optimal sensitivity (92.31%). Further combined analysis of the indices did not significantly improve the AUC. Moderate inverse correlations between the SUVmax, SUVmean, TLG, and the ADC ratio (rADC) were found in PCNSLs (r = -0.526, P = .002; r = -0.504, P = .004; and r = -0.483, P = .006; respectively).

CONCLUSIONS

The SUVmax and T/N ratio may be reliable measures for differentiating PCNSLs from GBMs. Additionally, FDG metabolism indices were inversely proportional to the rADCs of PCNSL lesions.

Voxel-wise correlation of functional imaging parameters in HNSCC patients receiving PET/MRI in an irradiation setup

PURPOSE

The purpose of this study was to demonstrate the feasibility of voxel-wise multiparametric characterization of head and neck squamous cell carcinomas (HNSCC) using hybrid multiparametric magnetic resonance imaging and positron emission tomography with [¹⁸F]-fluorodesoxyglucose (FDG-PET/MRI) in a radiation treatment planning setup.

METHODS

Ten patients with locally advanced HNSCC were examined with a combined FDG-PET/MRI in an irradiation planning setup. The multiparametric imaging protocol consisted of FDG-PET, T2-weighted transverse short tau inversion recovery sequence (STIR) and diffusion-weighted MRI (DWI). Primary tumours were manually segmented and quantitative imaging parameters were extracted. PET standardized uptake values (SUV) and DWI apparent diffusion coefficients (ADC) were correlated on a voxel-wise level.

RESULTS

Images acquired in this specialised radiotherapy planning setup achieved good diagnostic quality. Median tumour volume was 4.9 [1.1-42.1] ml. Mean PET SUV and ADC of the primary tumours were 5 ± 2.5 and 1.2 ± 0.3 10^-3 mm²/s, respectively. In voxel-wise correlation between ADC values and corresponding FDG SUV of the tumours, a significant negative correlation was observed (r = -0.31 ± 0.27, p < 0.05).

CONCLUSION

Multiparametric voxel-wise characterization of HNSCC is feasible using combined PET/MRI in a radiation planning setup. This technique may provide novel insights into tumour biology with regard to radiation therapy in the future.

MRI with DWI for the Detection of Posttreatment Head and Neck Squamous Cell Carcinoma: Why Morphologic MRI Criteria Matter

BACKGROUND AND PURPOSE

Although diffusion-weighted imaging combined with morphologic MRI (DWIMRI) is used to detect posttreatment recurrent and second primary head and neck squamous cell carcinoma, the diagnostic criteria used so far have not been clarified. We hypothesized that precise MRI criteria based on signal intensity patterns on T2 and contrast-enhanced T1 complement DWI and therefore improve the diagnostic performance of DWIMRI.

MATERIALS AND METHODS

We analyzed 1.5T MRI examinations of 100 consecutive patients treated with radiation therapy with or without additional surgery for head and neck squamous cell carcinoma. MRI examinations included morphologic sequences and DWI (b=0 and b=1000 s/mm²). Histology and follow-up served as the standard of reference. Two experienced readers, blinded to clinical/histologic/follow-up data, evaluated images according to clearly defined criteria for the diagnosis of recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment, post-radiation therapy inflammatory edema, and late fibrosis. DWI analysis included qualitative (visual) and quantitative evaluation with an ADC threshold.

RESULTS

Recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment was present in 36 patients, whereas 64 patients had post-radiation therapy lesions only. The Cohen κ for differentiating tumor from post-radiation therapy lesions with MRI and qualitative DWIMRI was 0.822 and 0.881, respectively. Mean ADCmean in recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment (1.097 ± 0.295 × 10^-3 mm²/s) was significantly lower (P < .05) than in post-radiation therapy inflammatory edema (1.754 ± 0.343 × 10^-3 mm²/s); however, it was similar to that in late fibrosis (0.987 ± 0.264 × 10^-3 mm²/s, P > .05). Although ADCs were similar in tumors and late fibrosis, morphologic MRI criteria facilitated distinction between the 2 conditions. The sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios (95% CI) of DWIMRI with ADCmean < 1.22 × 10^-3 mm²/s and precise MRI criteria were 92.1% (83.5-100.0), 95.4% (90.3-100.0), 92.1% (83.5-100.0), 95.4% (90.2-100.0), 19.9 (6.58-60.5), and 0.08 (0.03-0.24), respectively, indicating a good diagnostic performance to rule in and rule out disease.

CONCLUSIONS

Adding precise morphologic MRI criteria to quantitative DWI enables reproducible and accurate detection of recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment.

Evaluation of diffusion weighted imaging for tumor delineation in head-and-neck radiotherapy by comparison with automatically segmented 18F-fluorodeoxyglucose positron emission tomography

Background and purpose

Diffusion weighted (DW) MRI may facilitate target volume delineation for head-and-neck (HN) radiation treatment planning. In this study we assessed the use of a dedicated, geometrically accurate, DW-MRI sequence for target volume delineation. The delineations were compared with semi-automatic segmentations on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) images and evaluated for interobserver variation.

Methods and materials

Fifteen HN cancer patients underwent both DW-MRI and FDG-PET for RT treatment planning. Target delineation on DW-MRI was performed by three observers, while for PET a semi-automatic segmentation was performed using a Gaussian mixture model. For interobserver variation and intermodality variation, volumes, overlap metrics and Hausdorff distances were calculated from the delineations.

Results

The median volumes delineated by the three observers on DW-MRI were 10.8, 10.5 and 9.0 cm³ respectively, and was larger than the median PET volume (8.0 cm³). The median conformity index of DW-MRI for interobserver variation was 0.73 (range 0.38–0.80). Compared to PET, the delineations on DW-MRI by the three observers showed a median dice similarity coefficient of 0.71, 0.69 and 0.72 respectively. The mean Hausdorff distance was small with median (range) distances between PET and DW-MRI of 2.3 (1.5–6.8), 2.5 (1.6–6.9) and 2.0 (1.35–7.6) mm respectively. Over all patients, the median 95th percentile distances were 6.0 (3.0–13.4), 6.6 (4.0–24.0) and 5.3 (3.4–26.0) mm.

Conclusion

Using a dedicated DW-MRI sequence, target volumes could be defined with good interobserver agreement and a good overlap with PET. Target volume delineation using DW-MRI is promising in head-and-neck radiotherapy, combined with other modalities, it can lead to more precise target volume delineation.

Correlation between glycolytic activity on [18F]-FDG-PET and cell density on diffusion-weighted MRI in lymphoma at staging

BACKGROUND

[18F]-FDG-PET/MR carries a high diagnostic value in whole-body oncologic imaging and allows simultaneous quantitative measurements of glucose metabolism (SUV) and cell density (ADC).

PURPOSE

To determine the relationship between SUV and ADC values extracted from simultaneously acquired [18F]-FDG-PET/MR data of patients with FDG-avid lymphomas at staging.

STUDY TYPE

Prospective.

POPULATION

Patients with histologically proven lymphoma referred for staging.

FIELD STRENGTH/SEQUENCES

Hybrid PET/MR device (3T); axial, two-point Dixon, 3D, volume-interpolated, T₁ -weighted breath-hold sequence; coronal T₂ -weighted half-Fourier acquisition single-shot turbo spin-echo. Single-shot, echo-planar imaging-based, spectral adiabatic inversion recovery diffusion-weighted imaging.

ASSESSMENT

Staging was performed according to the modified Ann Arbor system by a board-certified radiologist and a board-certified nuclear medicine physician, blinded to the clinical and histological information, in consensus. SUVs and ADCs values were collected, for each positive nodal and extranodal region, from the lesion demonstrating the largest diameter.

STATISTICAL TESTS

Descriptive data included absolute frequencies and percentages for categorical data, and arithmetic means and 95% confidence intervals for scale-type data. The Pearson correlation coefficient was used to assess the relationship between SUVs and ADCs (P ≤ 0.05). Additional separate analyses were performed according to histological lymphoma subtype, for nodal and extranodal lesions and excluding bone lesions.

RESULTS

Overall, 100 patients were examined (55 males, 45 females; age ± SD in years, 51.6 ± 19.5). Histology revealed Hodgkin-lymphoma and non-Hodgkin-lymphoma in 26 and 74 patients, respectively. Twenty patients were stage I, 21 stage II, 24 stage III, and 31 stage IV on [18F]-FDG-PET/MR (ie, four patients negative at imaging). Based on 391 lesions (ie, 367 excluding bone lesions) no significant correlations between SUVmax and ADCmin, or between SUVmean and ADCmean, emerged (respectively, r = 0.091, P = 0.073, 95% CI [-0.01, 0.19] and r = -0.032, P = 0.527, 95% CI [-0.13, 0.07] including bone lesions; r = 0.06, P = 0.21, 95% CI [-0.04, 0.17] and r = -0.05, P = 0.32, 95% CI [-0.15, 0.05] excluding bone lesions). A significant correlation was observed only between ADCmean and SUVmean for follicular lymphoma (r = -0.33, P = 0.001).

DATA CONCLUSION

SUVs and ADCs were demonstrated to be independent biomarkers in lymphomas. A moderate correlation between SUVs and ADCs likely is present in follicular lymphoma.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1217-1226.

Injectable facial fillers: imaging features, complications, and diagnostic pitfalls at MRI and PET CT

Injectable fillers are widely used for facial rejuvenation, correction of disabling volumetric fat loss in HIV-associated facial lipoatrophy, Romberg disease, and post-traumatic facial disfiguring. The purpose of this article is to acquaint the reader with the anatomy of facial fat compartments, as well as with the properties and key imaging features of commonly used facial fillers, filler-related complications, interpretation pitfalls, and dermatologic conditions mimicking filler-related complications. The distribution of facial fillers is characteristic and depends on the anatomy of the superficial fat compartments. Silicone has signature MRI features, calcium hydroxyapatite has characteristic calcifications, whereas other injectable fillers have overlapping imaging features. Most fillers (hyaluronic acid, collagen, and polyalkylimide-polyacrylamide hydrogels) have signal intensity patterns compatible with high water content. On PET-CT, most fillers show physiologic high FDG uptake, which should not be confounded with pathology. Abscess, cellulitis, non-inflammatory nodules, and foreign body granulomas are the most common filler-related complications, and imaging can help in the differential diagnosis. Diffusion weighted imaging helps in detecting a malignant lesion masked by injected facial fillers. Awareness of imaging features of facial fillers and their complications helps to avoid misinterpretation of MRI, and PET-CT scans and facilitates therapeutic decisions in unclear clinical cases.

KEY POINTS

• Facial fillers are common incidental findings on MRI and PET-CT scans. • They have a characteristic appearance and typical anatomic distribution • Although considered as safe, facial filler injections are associated with several complications • As they may mask malignancy, knowledge of typical imaging features is mandatory. • MRI is a problem-solving tool for unclear cases.

Apparent Diffusion Coefficient Histograms of Human Papillomavirus-Positive and Human Papillomavirus-Negative Head and Neck Squamous Cell Carcinoma: Assessment of Tumor Heterogeneity and Comparison with Histopathology

BACKGROUND AND PURPOSE

Head and neck squamous cell carcinoma associated with human papillomavirus infection represents a distinct tumor entity. We hypothesized that diffusion phenotypes based on the histogram analysis of ADC values reflect distinct degrees of tumor heterogeneity in human papillomavirus-positive and human papillomavirus-negative head and neck squamous cell carcinomas.

MATERIALS AND METHODS

One hundred five consecutive patients (mean age, 64 years; range, 45-87 years) with primary oropharyngeal (n = 52) and oral cavity (n = 53) head and neck squamous cell carcinoma underwent MR imaging with anatomic and diffusion-weighted sequences (b = 0, b = 1000 s/mm², monoexponential ADC calculation). The collected tumor voxels from the contoured ROIs provided histograms from which position, dispersion, and form parameters were computed. Histogram data were correlated with histopathology, p16-immunohistochemistry, and polymerase chain reaction for human papillomavirus DNA.

RESULTS

There were 21 human papillomavirus-positive and 84 human papillomavirus-negative head and neck squamous cell carcinomas. At histopathology, human papillomavirus-positive cancers were more often nonkeratinizing (13/21, 62%) than human papillomavirus-negative cancers (19/84, 23%; P = .001), and their mitotic index was higher (71% versus 49%; P = .005). ROI-based mean and median ADCs were significantly lower in human papillomavirus-positive (1014 ± 178 × 10^-6 mm²/s and 970 ± 187 × 10^-6 mm²/s, respectively) than in human papillomavirus-negative tumors (1184 ± 168 × 10^-6 mm²/s and 1161 ± 175 × 10^-6 mm²/s, respectively; P < .001), whereas excess kurtosis and skewness were significantly higher in human papillomavirus-positive (1.934 ± 1.386 and 0.923 ± 0.510, respectively) than in human papillomavirus-negative tumors (0.643 ± 0.982 and 0.399 ± 0.516, respectively; P < .001). Human papillomavirus-negative head and neck squamous cell carcinoma had symmetric normally distributed ADC histograms, which corresponded histologically to heterogeneous tumors with variable cellularity, high stromal component, keratin pearls, and necrosis. Human papillomavirus-positive head and neck squamous cell carcinomas had leptokurtic skewed right histograms, which corresponded to homogeneous tumors with back-to-back densely packed cells, scant stromal component, and scattered comedonecrosis.

CONCLUSIONS

Diffusion phenotypes of human papillomavirus-positive and human papillomavirus-negative head and neck squamous cell carcinomas show significant differences, which reflect their distinct degree of tumor heterogeneity.

Local recurrence of squamous cell carcinoma of the head and neck after radio(chemo)therapy: Diagnostic performance of FDG-PET/MRI with diffusion-weighted sequences

PURPOSE

To determine the diagnostic performance of FDG-PET/MRI with diffusion-weighted imaging (FDG-PET/DWIMRI) for detection and local staging of head and neck squamous cell carcinoma (HNSCC) after radio(chemo)therapy.

MATERIALS AND METHODS

This was a prospective study that included 74 consecutive patients with previous radio(chemo)therapy for HNSCC and in whom tumour recurrence or radiation-induced complications were suspected clinically. The patients underwent hybrid PET/MRI examinations with morphological MRI, DWI and FDG-PET. Experienced readers blinded to clinical/histopathological data evaluated images according to established diagnostic criteria taking into account the complementarity of multiparametric information. The standard of reference was histopathology with whole-organ sections and follow-up ≥24 months. Statistical analysis considered data clustering.

RESULTS

The proof of diagnosis was histology in 46/74 (62.2%) patients and follow-up (mean ± SD = 34 ± 8 months) in 28/74 (37.8%). Thirty-eight patients had 43 HNSCCs and 46 patients (10 with and 36 without tumours) had 62 benign lesions/complications. Sensitivity, specificity, and positive and negative predictive value of PET/DWIMRI were 97.4%, 91.7%, 92.5% and 97.1% per patient, and 93.0%, 93.5%, 90.9%, and 95.1% per lesion, respectively. Agreement between imaging-based and pathological T-stage was excellent (kappa = 0.84, p < 0.001).

CONCLUSION

FDG-PET/DWIMRI yields excellent results for detection and T-classification of HNSCC after radio(chemo)therapy.

KEY POINTS

• FDG-PET/DWIMRI yields excellent results for the detection of post-radio(chemo)therapy HNSCC recurrence. • Prospective one-centre study showed excellent agreement between imaging-based and pathological T-stage. • 97.5% of positive concordant MRI, DWI and FDG-PET results correspond to recurrence. • 87% of discordant MRI, DWI and FDG-PET results correspond to benign lesions. • Multiparametric FDG-PET/DWIMRI facilitates planning of salvage surgery in the irradiated neck.

State of the art MRI in head and neck cancer

Head and neck cancer affects more than 11,000 new patients per year in the UK¹ and imaging has an important role in the diagnosis, treatment planning, and assessment, and post-treatment surveillance of these patients. The anatomical detail produced by magnetic resonance imaging (MRI) is ideally suited to staging and follow-up of primary tumours and cervical nodal metastases in the head and neck; however, anatomical images have limitations in cancer imaging and so increasingly functional-based MRI techniques, which provide molecular, metabolic, and physiological information, are being incorporated into MRI protocols. This article reviews the state of the art of these functional MRI techniques with emphasis on those that are most relevant to the current management of patients with head and neck cancer.

CD44v6-Targeted Imaging of Head and Neck Squamous Cell Carcinoma: Antibody-Based Approaches

Head and neck squamous cell carcinoma (HNSCC) is a common and severe cancer with low survival rate in advanced stages. Noninvasive imaging of prognostic and therapeutic biomarkers could provide valuable information for planning and monitoring of the different therapy options. Thus, there is a major interest in development of new tracers towards cancer-specific molecular targets to improve diagnostic imaging and treatment. CD44v6, an oncogenic variant of the cell surface molecule CD44, is a promising molecular target since it exhibits a unique expression pattern in HNSCC and is associated with drug- and radio-resistance. In this review we summarize results from preclinical and clinical investigations of radiolabeled anti-CD44v6 antibody-based tracers: full-length antibodies, Fab, F(ab′)₂ fragments, and scFvs with particular focus on the engineering of various antibody formats and choice of radiolabel for the use as molecular imaging agents in HNSCC. We conclude that the current evidence points to CD44v6 imaging being a promising approach for providing more specific and sensitive diagnostic tools, leading to customized treatment decisions and functional diagnosis. Improved imaging tools hold promise to enable more effective treatment for head and neck cancer patients.

Detection of crossed cerebellar diaschisis in hyperacute ischemic stroke using arterial spin-labeled MR imaging

Background and purpose

Arterial spin-labeling (ASL) was recently introduced as a noninvasive method to evaluate cerebral hemodynamics. The purposes of this study were to assess the ability of ASL imaging to detect crossed cerebellar diaschisis (CCD) in patients with their first unilateral supratentorial hyperacute stroke and to identify imaging or clinical factors significantly associated with CCD.

Materials and methods

We reviewed 204 consecutive patients who underwent MRI less than 8 hours after the onset of stroke symptoms. The inclusion criteria were supratentorial abnormality in diffusion-weighted images in the absence of a cerebellar or brain stem lesion, bilateral supratentorial infarction, subacute or chronic infarction, and MR angiography showing vertebrobasilar system disease. For qualitative analysis, asymmetric cerebellar hypoperfusion in ASL images was categorized into 3 grades. Quantitative analysis was performed to calculate the asymmetric index (AI). The patients’ demographic and clinical features and outcomes were recorded. Univariate and multivariate analyses were also performed.

Results

A total of 32 patients met the inclusion criteria, and 24 (75%) presented CCD. Univariate analyses revealed more frequent arterial occlusions, higher diffusion-weighted imaging (DWI) lesion volumes and higher initial NIHSS and mRS scores in the CCD-positive group compared with the CCD-negative group (all p < .05). The presence of arterial occlusion and the initial mRS scores were related with the AI (all p < .05). Multivariate analyses revealed that arterial occlusion and the initial mRS scores were significantly associated with CCD and AI.

Conclusion

ASL imaging could detect CCD in 75% of patients with hyperacute infarction. We found that CCD was more prevalent in patients with arterial occlusion, larger ischemic brain volumes, and higher initial NIHSS and mRS scores. In particular, vessel occlusion and initial mRS score appeared to be significantly related with CCD pathophysiology in the hyperacute stage.

Non-odontogenic tumors of the facial bones in children and adolescents: role of multiparametric imaging

Tumors of the pediatric facial skeleton represent a major challenge in clinical practice because they can lead to functional impairment, facial deformation, and long-term disfigurement. Their treatment often requires a multidisciplinary approach, and radiologists play a pivotal role in the diagnosis and management of these lesions. Although rare, pediatric tumors arising in the facial bones comprise a wide spectrum of benign and malignant lesions of osteogenic, fibrogenic, hematopoietic, neurogenic, or epithelial origin. The more common lesions include Langerhans cell histiocytosis and osteoma, while rare lesions include inflammatory myofibroblastic and desmoid tumors; juvenile ossifying fibroma; primary intraosseous lymphoma; Ewing sarcoma; and metastases to the facial bones from neuroblastoma, Ewing sarcoma, or retinoblastoma. This article provides a comprehensive approach for the evaluation of children with non-odontogenic tumors of the facial skeleton. Typical findings are discussed with emphasis on the added value of multimodality multiparametric imaging with computed tomography (CT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI), positron emission tomography CT (PET CT), and PET MRI. Key imaging findings and characteristic histologic features of benign and malignant lesions are reviewed and the respective role of each modality for pretherapeutic assessment and post-treatment follow-up. Pitfalls of image interpretation are addressed and how to avoid them.

Meta-Analysis of the Correlation between Apparent Diffusion Coefficient and Standardized Uptake Value in Malignant Disease

The objective of this meta-analysis is to explore the correlation between the apparent diffusion coefficient (ADC) on diffusion-weighted MR and the standard uptake value (SUV) of ¹⁸F-FDG on PET/CT in patients with cancer. Databases such as PubMed (MEDLINE included), EMBASE, and Cochrane Database of Systematic Review were searched for relevant original articles that explored the correlation between SUV and ADC in English. After applying Fisher's r-to-z transformation, correlation coefficient (r) values were extracted from each study and 95% confidence intervals (CIs) were calculated. Sensitivity and subgroup analyses based on tumor type were performed to investigate the potential heterogeneity. Forty-nine studies were eligible for the meta-analysis, comprising 1927 patients. Pooled r for all studies was −0.35 (95% CI: −0.42–0.28) and exhibited a notable heterogeneity (I² = 78.4%; P < 0.01). In terms of the cancer type subgroup analysis, combined correlation coefficients of ADC/SUV range from −0.12 (lymphoma, n = 5) to −0.59 (pancreatic cancer, n = 2). We concluded that there is an average negative correlation between ADC and SUV in patients with cancer. Higher correlations were found in the brain tumor, cervix carcinoma, and pancreas cancer. However, a larger, prospective study is warranted to validate these findings in different cancer types.

Multimodality functional imaging using DW-MRI and 18F-FDG-PET/CT during radiation therapy for human papillomavirus negative head and neck squamous cell carcinoma: Meixoeiro Hospital of Vigo Experience

AIM

To noninvasively investigate tumor cellularity measured using diffusion-weighted magnetic resonance imaging (DW-MRI) and glucose metabolism measured by ¹⁸F-labeled fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) during radiation therapy (RT) for human papillomavirus negative (HPV-) head and neck squamous cell carcinoma (HNSCC).

METHODS

In this prospective study, 6 HPV- HNSCC patients underwent a total of 34 multimodality imaging examinations (DW-MRI at 1.5 T Philips MRI scanner [(n = 24) pre-, during- (2-3 wk), and post-treatment (Tx), and ¹⁸F-FDG PET/CT pre- and post-Tx (n = 10)]. All patients received RT. Monoexponential modeling of the DW-MRI data yielded the imaging metric apparent diffusion coefficient (ADC) and the mean of standardized uptake value (SUV) was measured from ¹⁸F-FDG PET uptake. All patients had a clinical follow-up as the standard of care and survival status was documented at 1 year.

RESULTS

There was a strong negative correlation between the mean of pretreatment ADC (ρ = -0.67, P = 0.01) and the pretreatment ¹⁸F-FDG PET SUV. The percentage (%) change in delta (∆) ADC for primary tumors and neck nodal metastases between pre- and Wk_2-3 Tx were as follows: 75.4% and 61.6%, respectively, for the patient with no evidence of disease, 27.5% and 32.7%, respectively, for those patients who were alive with disease, and 26.9% and 7.31%, respectively, for those who were dead with disease.

CONCLUSION

These results are preliminary in nature and are indicative, and not definitive, trends rendered by the imaging metrics due to the small sample size of HPV- HNSCC patients in a Meixoeiro Hospital of Vigo Experience.

Feasibility of Multiparametric Imaging with PET/MR in Head and Neck Squamous Cell Carcinoma

The purpose of this study was to investigate and assess the correlation and reproducibility of multiparametric imaging in head and neck cancer patients.

METHODS

Twenty-one patients were included in this prospective scan-rescan study. All patients were scanned twice on an integrated PET and MRI scanner. Gross tumor volumes were defined on T2-weighted MR images, and volumes of interest were defined on diffusion-weighted MRI and 18F-FDG PET (VOIDWI, VOIPET). Overlap between volumes was assessed as a percentwise overlap. 18F-FDG uptake and diffusion were measured using SUV and apparent diffusion coefficient, and correlation was tested across and within patients and as a voxel-by-voxel analysis.

RESULTS

Seventeen patients were available for correlation analysis, and 12 patients were available for assessment of tumor overlap. The median tumor overlap between VOIDWI and VOIPET was 82% (VOIDWI in VOIPET) and 62% (VOIPET in VOIDWI) on scan 1 and scan 2, respectively. Across patients, the correlation between SUV and apparent diffusion coefficient was weak and nonsignificant. However, in individual patients a weak but significant correlation was identified on a voxel-by-voxel basis.

CONCLUSION

In multiparametric imaging with the integrated PET/MR scanner, the VOIs from DWI and 18F-FDG PET were both within the target volume for radiotherapy and overlapped substantially although not completely. No correlation between 18F-FDG uptake and DWI could be found across patients, but within individual patients a statistically significant, but weak, voxel-by-voxel correlation was found. The findings suggest that information on glucose uptake and diffusion coefficient carries complementary information of interest that may be relevant for radiotherapy treatment planning.

Apparent diffusion coefficient for discriminating metastatic lymph nodes in patients with squamous cell carcinoma of the head and neck

PURPOSE

We aimed to evaluate the apparent diffusion coefficient (ADC) values of metastatic lymph nodes in patients with squamous cell carcinoma (SCC) of the head and neck.

METHODS

Patients with metastatic lymph nodes underwent 1.5 Tesla diffusion-weighted magnetic resonance imaging (MRI). The ADC values of the histologically proven metastases were evaluated retrospectively and mean ADC values were compared using one-way analysis of variance test. Receiver operating characteristic analysis was performed to identify ADC threshold values.

RESULTS

We included 33 patients (27 males, 6 females; mean age, 60.7 years) with 53 metastatic lymph nodes in the study. Mean ADC values for nodal metastases of nasopharyngeal carcinoma (NPC) (n=7), oropharyngeal (n=12), laryngeal (n=27), and hypopharyngeal (n=7) carcinoma were (0.810±0.158)×10-3 mm2/s, (0.985±0.099)×10-3 mm2/s, (1.037±0.150)×10-3 mm2/s, and (0.948±0.081)×10-3 mm2/s, respectively. The mean ADC values of nodal metastases of NPC were significantly lower than ADC values of laryngeal carcinoma (LSCC) (P = 0.002). An ADC value less than 0.890×10-3 mm2/s was found to facilitate differentiation of NPC from LSCC with a sensitivity of 71% and specificity of 85% (area under the curve, 0.852).

CONCLUSION

The mean ADC values showed significant differences between nodal metastases of NPC and LSCC. Considering SCCs as a single group may affect the accuracy of ADC-based differentiation. Location of the primary tumor should be taken into account and cutoff values should be determined separately for each anatomical location.