Evaluating Tumors and Tumorlike Lesions of the Nasal Cavity, the Paranasal Sinuses, and the Adjacent Skull Base With Diffusion-Weighted MRI

Synthetic MRI and amide proton transfer-weighted MRI for differentiating between benign and malignant sinonasal lesions

OBJECTIVES

To explore the value of the synthetic MRI (SyMRI), combined with amide proton transfer-weighted (APTw) MRI for quantitative and morphologic assessment of sinonasal lesions, which could provide relative scale for the quantitative assessment of tissue properties.

METHODS

A total of 80 patients (31 malignant and 49 benign) with sinonasal lesions, who underwent the SyMRI and APTw examination, were retrospectively analyzed. Quantitative parameters (T1, T2, proton density (PD)) and APT % were obtained through outlining the region of interest (ROI) and comparing the two groups utilizing independent Student t test or a Wilcoxon test. Receiver operating characteristic curve (ROC), Delong test, and logistic regression analysis were performed to assess the diagnostic efficiency of one-parameter and multiparametric models.

RESULTS

SyMRI-derived mean T1, T2, and PD were significantly higher and APT % was relatively lower in benign compared to malignant sinonasal lesions (p < 0.05). The ROC analysis showed that the AUCs of the SyMRI-derived quantitative (T1, T2, PD) values and APT % ranged from 0.677 to 0.781 for differential diagnosis between benign and malignant sinonasal lesions. The T2 values showed the best diagnostic performance among all single parameters for differentiating these two masses. The AUCs of combined SyMRI-derived multiple parameters with APT % (AUC = 0.866) were the highest than that of any single parameter, which was significantly improved (p < 0.05).

CONCLUSION

The combination of SyMRI and APTw imaging has the potential to reflect intrinsic tissue characteristics useful for differentiating benign from malignant sinonasal lesions.

CLINICAL RELEVANCE STATEMENT

Combining synthetic MRI with amide proton transfer-weighted imaging could function as a quantitative and contrast-free approach, significantly enhancing the differentiation of benign and malignant sinonasal lesions and overcoming the limitations associated with the superficial nature of endoscopic nasal sampling.

KEY POINTS

• Synthetic MRI and amide proton transfer-weighted MRI could differentiate benign from malignant sinonasal lesions based on quantitative parameters. • The diagnostic efficiency could be significantly improved through synthetic MRI + amide proton transfer-weighted imaging. • The combination of synthetic MRI and amide proton transfer-weighted MRI is a noninvasive method to evaluate sinonasal lesions.

Correlation between diffusion-weighted image-derived parameters and dynamic contrast-enhanced magnetic resonance imaging-derived parameters in the orofacial region

Background

Diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are widely used in the orofacial region. Furthermore, quantitative analyses have proven useful. However, a few reports have described the correlation between DWI-derived parameters and DCE-MRI-derived parameters, and the results have been controversial.

Purpose

To evaluate the correlation among parameters obtained by DWI and DCE-MRI and to compare them between benign and malignant lesions.

Material and Methods

Fifty orofacial lesions were analysed. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) were estimated by DWI. For DCE-MRI, TK model analysis was performed to estimate physiological parameters, for example, the influx forward volume transfer constant into the extracellular-extravascular space (EES) (Ktrans) and fractional volumes of EES and plasma components (ve and vp).

Results

Both ADC and D showed a moderate positive correlation with ve (ρ = 0.640 and 0.645, respectively). Ktrans showed a marginally weak correlation with f (ρ = 0.296), while vp was not correlated with f or D*; therefore, IVIM perfusion-related parameters and TK model perfusion-related parameters were not straightforward. Both D and ve yielded high diagnostic power between benign lesions and malignant tumours with areas under the curve (AUCs) of 0.830 and 0.782, respectively.

Conclusion

Both D and ve were reliable parameters that were useful for the differential diagnosis. In addition, the true diffusion coefficient (D) was affected by the fractional volume of EES.

Diagnosis and management of extramedullary plasmacytoma in nasal cavity: Clinical experience and literature review

Nasal extramedullary plasmacytoma (EMP) is a rare plasma cell tumor that occurs in the soft tissue of the nasal cavity, and its imaging characteristics are still unclear. The purpose of this study was to investigate the clinical features, imaging findings, treatment, survival analysis, and prognosis of nasal EMP, and to provide a systematic review of the patients we treated and the published literature. A 45-year-old female patient who presented with epistaxis with nasal obstruction was recommended for magnetic resonance imaging to assess the nature of the lesion. On magnetic resonance imaging, abnormal signal shadow can be seen in the right nasal cavity. Diffusion weighted imaging showed signal of the lesion was significantly limited, presenting high signal, with a low apparent dispersion coefficient, and the lesion was significantly enhanced on contrast-enhanced scan. Combined with the clinical manifestations of the patient, who was initially considered to have a hemangioma. She underwent endoscopic nasal surgery under general anesthesia to remove the mass, and the final pathology confirmed it was EMP. However, the final pathology confirmed EMP. Five months later, the patient came to our hospital for follow-up and underwent fluorine-18-fluorodeoxyglucose/positron emission tomography/computed tomography scan, which showed no recurrence of the lesion and no transformation of multiple myeloma. The nasal EMP imaging findings were mostly soft tissue masses with uniform density or signal, which were significantly enhanced by enhancement scan, high signal on diffusion weighted imaging and low signal on apparent dispersion coefficient. Immunohistochemical staining for CD38, CD138, and CD79a was positive in most of the cases evaluated, while CD20 and CD10 were negative. The absence of dilated features, infiltrative features and the presence of significant contrast enhancement may be relatively specific imaging findings of nasal EMP. The prognosis of nasal EMP is good, and recurrence, metastasis, and transformation into multiple myeloma are rare. Because the lesions are sensitive to radiotherapy, surgical resection combined with radiotherapy is a more effective treatment.

The value of intravoxel incoherent motion model-based diffusion-weighted imaging for predicting long-term outcomes in nasopharyngeal carcinoma

Objective

The aim of this study was to evaluate the prognostic value for survival of parameters derived from intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in patients with nasopharyngeal carcinoma (NPC).

Materials

Baseline IVIM-DWI was performed on 97 newly diagnosed NPC patients in this prospective study. The relationships between the pretreatment IVIM-DWI parametric values (apparent diffusion coefficient (ADC), D, D*, and f) of the primary tumors and the patients’ 3-year survival were analyzed in 97 NPC patients who received chemoradiotherapy. The cutoff values of IVIM parameters for local relapse-free survival (LRFS) were identified by a non-parametric log-rank test. The local-regional relapse-free survival (LRRFS), LRFS, regional relapse-free survival (RRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) rates were calculated by using the Kaplan–Meier method. A Cox proportional hazards model was used to explore the independent predictors for prognosis.

Results

There were 97 participants (mean age, 48.4 ± 10.5 years; 65 men) analyzed. Non-parametric log-rank test results showed that the optimal cutoff values of ADC, D, D*, and f were 0.897 × 10−3 mm2/s, 0.699 × 10−3 mm2/s, 8.71 × 10−3 mm2/s, and 0.198%, respectively. According to the univariable analysis, the higher ADC group demonstrated significantly higher OS rates than the low ADC group (p = 0.036), the higher D group showed significantly higher LRFS and OS rates than the low D group (p = 0.028 and p = 0.017, respectively), and the higher D* group exhibited significantly higher LRFS and OS rates than the lower D* group (p = 0.001 and p = 0.002, respectively). Multivariable analyses indicated that ADC and D were the independent prognostic factors for LRFS (p = 0.041 and p = 0.037, respectively), D was an independent prognostic factor for LRRFS (p = 0.045), D* and f were the independent prognostic factors for OS (p = 0.019 and 0.029, respectively), and f acted was an independent prognostic factor for DMFS (p = 0.020).

Conclusions

Baseline IVIM-DWI perfusion parameters ADC and D, together with diffusion parameter D*, could act as useful factors for predicting long-term outcomes and selecting high-risk patients with NPC.

Machine learning to differentiate small round cell malignant tumors and non-small round cell malignant tumors of the nasal and paranasal sinuses using apparent diffusion coefficient values

OBJECTIVE

We used radiomics feature-based machine learning classifiers of apparent diffusion coefficient (ADC) maps to differentiate small round cell malignant tumors (SRCMTs) and non-SRCMTs of the nasal and paranasal sinuses.

MATERIALS

A total of 267 features were extracted from each region of interest (ROI). Datasets were randomized into two sets, a training set (∼70%) and a test set (∼30%). We performed dimensional reductions using the Pearson correlation coefficient and feature selection analyses (analysis of variance [ANOVA], relief, recursive feature elimination [RFE]) and classifications using 10 machine learning classifiers. Results were evaluated with a leave-one-out cross-validation analysis.

RESULTS

We compared the AUC for all the pipelines in the validation dataset using FeAture Explorer (FAE) software. The pipeline using RFE feature selection and Gaussian process classifier yielded the highest AUCs with ten features. When the "one-standard error" rule was used, FAE produced a simpler model with eight features, including Perc.01%, Perc.10%, Perc.90%, Perc.99%, S(1,0) SumAverg, S(5,5) AngScMom, S(5,5) Correlat, and WavEnLH_s-2. The AUCs of the training, validation, and test datasets achieved 0.995, 0.902, and 0.710, respectively. For ANOVA, the pipeline with the auto-encoder classifier yielded the highest AUC using only one feature, Perc.10% (training/validation/test datasets: 0.886/0.895/0.809, respectively). For the relief, the AUCs of the training, validation, and test datasets that used the LRLasso classifier using five features (Perc.01%, Perc.10%, S(4,4) Correlat, S(5,0) SumAverg, S(5,0) Contrast) were 0.892, 0.886, and 0.787, respectively. Compared with the RFE and relief, the results of all algorithms of ANOVA feature selection were more stable with the AUC values higher than 0.800.

CONCLUSIONS

We demonstrated the feasibility of combining artificial intelligence with the radiomics from ADC values in the differential diagnosis of SRCMTs and non-SRCMTs and the potential of this non-invasive approach for clinical applications.

KEY POINTS

• The parameter with the best diagnostic performance in differentiating SRCMTs from non-SRCMTs was the Perc.10% ADC value. • Results of all the algorithms of ANOVA feature selection were more stable and the AUCs were higher than 0.800, as compared with RFE and relief. • The pipeline using RFE feature selection and Gaussian process classifier yielded the highest AUC.

Texture Analysis of Fat-Suppressed T2-Weighted Magnetic Resonance Imaging and Use of Machine Learning to Discriminate Nasal and Paranasal Sinus Small Round Malignant Cell Tumors

Objective

We used texture analysis and machine learning (ML) to classify small round cell malignant tumors (SRCMTs) and Non-SRCMTs of nasal and paranasal sinus on fat-suppressed T2 weighted imaging (Fs-T2WI).

Materials

Preoperative MRI scans of 164 patients from 1 January 2018 to 1 January 2021 diagnosed with SRCMTs and Non-SRCMTs were included in this study. A total of 271 features were extracted from each regions of interest. Datasets were randomly divided into two sets, including a training set (∼70%) and a test set (∼30%). The Pearson correlation coefficient (PCC) and principal component analysis (PCA) methods were performed to reduce dimensions, and the Analysis of Variance (ANOVA), Kruskal-Wallis (KW), and Recursive Feature Elimination (RFE) and Relief were performed for feature selections. Classifications were performed using 10 ML classifiers. Results were evaluated using a leave one out cross-validation analysis.

Results

We compared the AUC of all pipelines on the validation dataset with FeAture Explorer (FAE) software. The pipeline using a PCC dimension reduction, relief feature selection, and gaussian process (GP) classifier yielded the highest area under the curve (AUC) using 15 features. When the “one-standard error” rule was used, FAE also produced a simpler model with 13 features, including S(5,-5)SumAverg, S(3,0)InvDfMom, Skewness, WavEnHL_s-3, Horzl_GlevNonU, Horzl_RLNonUni, 135dr_GlevNonU, WavEnLL_s-3, Teta4, Teta2, S(5,5)DifVarnc, Perc.01%, and WavEnLH_s-2. The AUCs of the training/validation/test datasets were 1.000/0.965/0.979, and the accuracies, sensitivities, and specificities were 0.890, 0.880, and 0.920, respectively. The best algorithm was GP whose AUCs of the training/validation/test datasets by the two-dimensional reduction methods and four feature selection methods were greater than approximately 0.800. Especially, the AUCs of different datasets were greater than approximately 0.900 using the PCC, RFE/Relief, and GP algorithms.

Conclusions

We demonstrated the feasibility of combining artificial intelligence and the radiomics from Fs-T2WI to differentially diagnose SRCMTs and Non-SRCMTs. This non-invasive approach could be very promising in clinical oncology.

Turbo Gradient and Spin Echo PROPELLER-Diffusion Weighted Imaging for Orbital Tumors: A Comparative Study With Readout-Segmented Echo-Planar Imaging

Purpose: To qualitatively and quantitatively compare the image quality and diagnostic performance of turbo gradient and spin echo PROPELLER diffusion-weighted imaging (TGSE-PROPELLER-DWI) vs. readout-segmented echo-planar imaging (rs-EPI) in the evaluation of orbital tumors.

Materials and Methods: A total of 43 patients with suspected orbital tumors were enrolled to perform the two DWIs with comparable spatial resolution on 3T. The overall image qualities, geometric distortions, susceptibility artifacts, and lesion conspicuities were scored by using a four-point scale (1, poor; 4, excellent). Quantitative measurements, including contrast-to-noise ratios (CNRs), apparent diffusion coefficients (ADCs), geometric distortion rates (GDRs), and lesion sizes, were calculated and compared. The two ADCs for differentiating malignant from benign orbital tumors were evaluated. Wilcoxon signed-rank test, Kappa statistic, and receiver operating characteristics (ROC) curves were used.

Results: TGSE-PROPELLER-DWI performed superior in all subjective scores and quantitative GDR evaluation than rs-EPI (p < 0.001), and excellent interobserver agreement was obtained for Kappa value ranging from 0.876 to 1.000. ADC_lesion of TGSE-PROPELLER-DWI was significantly higher than those of rs-EPI (p < 0.001). Mean ADC of malignant tumors was significantly lower than that of benign tumors both in two DWIs. However, the AUC for differentiating malignant and benign tumors showed no significant difference in the two DWIs (0.860 vs. 0.854, p = 0.7448). Sensitivity and specificity could achieve 92.86% and 72.73% for TGSE-PROPELLER-DWI with a cutoff value of 1.23 × 10^–3 mm²/s, and 85.71% and 81.82% for rs-EPI with a cutoff value of 0.99 × 10^–3 mm²/s.

Conclusion: Compared with rs-EPI, TGSE-PROPELLER-DWI showed minimized geometric distortion and susceptibility artifacts significantly improved the image quality for orbital tumors and achieved comparable diagnostic performance in differentiating malignant and benign orbital tumors.

Dual-energy CT in differentiating benign sinonasal lesions from malignant ones: comparison with simulated single-energy CT, conventional MRI, and DWI

OBJECTIVES

To explore the value of dual-energy CT (DECT) for differentiating benign sinonasal lesions from malignant ones, and to compare this finding with simulated single-energy CT (SECT), conventional MRI (cMRI), and diffusion-weighted imaging (DWI).

METHODS

Patients with sinonasal lesions (38 benign and 34 malignant) who were confirmed by histopathology underwent DECT, cMRI, and DWI. DECT-derived parameters (iodine concentration (IC), effective atomic number (Eff-Z), 40-180 keV (20-keV interval), virtual non-enhancement (VNC), slope (k), and linear-mixed 0.3 (Mix-0.3)), DECT morphological features, cMRI characteristics, and ADC value of benign and malignant tumors were compared using t test or chi-square test. Receiver operating characteristic (ROC) curve was performed to evaluate the diagnostic performance, and the area under the ROC curve (AUC) was compared using the Z test to select the optimal diagnostic approach.

RESULTS

Significantly higher DECT-derived single parameters (IC, Eff-Z, 40 keV, 60 keV, 80 keV, slope (k), Mix-0.3) were found in malignant lesions than those of benign sinonasal lesions (all p < 0.004, Bonferroni correction). Combined quantitative parameters (IC, Eff-Z, 40 keV, 60 keV, 80 keV, slope (k)) can improve the diagnostic efficiency for discriminating these two entities. Combination of DECT quantitative parameters and morphological features can further improve the overall diagnostic performance, with AUC, sensitivity, specificity, and accuracy of 0.935, 96.67%, 90.00%, and 93.52%. Moreover, the AUC of DECT was higher than those of Mix-0.3 (simulated SECT), cMRI, DWI, and cMRI+DWI.

CONCLUSIONS

Compared with simulated SECT, cMRI, and DWI, DECT appears to be a more accurate imaging technique for differentiating benign from malignant sinonasal lesions.

KEY POINTS

• DE can differentiate benign sinonasal lesions from malignant ones based on DECT-derived qualitative parameters. • DECT appears to be more accurate in the diagnosis of sinonasal lesions when compared with simulated SECT, cMRI, and DWI.

Apparent Diffusion Coefficient for Distinguishing Between Malignant and Benign Lesions in the Head and Neck Region: A Systematic Review and Meta-Analysis

Background: The purpose of the present meta-analysis was to provide evident data about use of apparent diffusion coefficient (ADC) values for distinguishing malignant and benign lesions in the head and neck region.

Material and Methods: MEDLINE and Scopus databases were screened for associations between ADC and malignancy/benignancy of head and neck lesions up to December 2018. Overall, 22 studies met the inclusion criteria. The following data were extracted: authors, year of publication, study design, number of patients/lesions, lesion type, mean value, and standard deviation of ADC. The primary endpoint of the systematic review was the analysis of the association between lesion nature and ADC values. The methodological quality of the involved studies was checked according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) instrument. The meta-analysis was undertaken by using RevMan 5.3 software. DerSimonian and Laird random-effects models with inverse-variance weights were used without further correction to account for the heterogeneity between the studies. Mean ADC values including 95% confidence intervals were calculated separately for benign and malignant lesions.

Results: The acquired 22 studies comprised 1,227 lesions. Different malignant lesions were diagnosed in 818 cases (66.7%) and benign lesions in 409 cases (33.3%). The mean ADC value of the malignant lesions was 1.04 × 10⁻³ mm²/s, and the mean value of the benign lesions was 1.46 × 10⁻³ mm²/s. Lymphomas and sarcomas showed the lowest calculated mean ADC values, 0.7 and 0.79 × 10⁻³ mm²/s, respectively. Adenoid cystic carcinomas had the highest ADC values (1.5 × 10⁻³ mm²/s). None of the analyzed malignant tumors had mean ADC values above 1.75 × 10⁻³ mm²/s.

Conclusion: ADC values play a limited role in distinguishing between malignant and benign lesions in the head and neck region. It may be only suggested that lesions with mean ADC values above 1.75 × 10⁻³ mm²/s are probably benign. Further large studies are needed for the analysis of the role of diffusion-weighted imaging (DWI)/ADC in the discrimination of benign and malignant lesions in the head and neck region.

Role of diffusion-weighted imaging in the discrimination of purulent intrasinusal content: A retrospective study

OBJECTIVES

The objective of this study was to analyse MRI with morphological (T1, T2) and diffusion sequences (DWI, b1000) in patients presenting non-aggressive patterns of sinus opacity and operated on by functional endoscopic sinus surgery (FESS).

DESIGN

A retrospective study.

SETTING

Diffusion imaging in paranasal sinus pathology remains little known. To date, no imaging system is capable of determining the purulent content of a non-enhanced sinus filling.

PARTICIPANTS

We included consecutive patients having undergone FESS in whom MRI of the paranasal sinuses was performed. Subjects were allocated to Case (pus) or Control (no pus) groups depending on sinus content found intraoperatively. FESS was performed for bacterial acute rhinosinusitis, acute exacerbations of chronic rhinosinusitis, non-purulent sinusitis, naso-sinusal polyposis, antrochoanal polyp, isolated polyp, angiomatous polyp and eosinophilic fungal sinusitis. Tumours, mucoceles and fungus balls were excluded.

MAIN OUTCOME MEASURES

We analysed T1, T2, b1000 and MRI sequences and ADC map.

RESULTS

On univariate analysis, intermediate signal in T2 and high signal in b1000 were associated with Cases (P < 0.001) as were low ADC values (P < 0.001). The difference in mean ADC values between Cases and Controls was statistically significant (respectively, 0.518 vs 2.041 × 10^-3  mm² /sec, P < 0.01). On multivariate analysis, MRI with ADC < 0.725 × 10^-3  mm² /sec and b1000_SI > brain was significantly associated with the case group. MRI with b1000_SI < brain and ADC > 1.450 × 10^-3  mm² /sec was significantly associated with the control group.

CONCLUSIONS

Diffusion MRI offers extremely promising results regarding content characterisation of infectious sinus diseases.

Whole-tumor histogram analysis of monoexponential and advanced diffusion-weighted imaging for sinonasal malignant tumors: Correlations with histopathologic features

BACKGROUND

The histopathological basis of monoexponential diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI) in the characterization of sinonasal malignant tumors is still unclear.

PURPOSE

To explore the correlations of histogram metrics from monoexponential DWI, IVIM, and DKI with histopathologic features in sinonasal malignant tumors.

STUDY TYPE

Retrospective.

SUBJECTS

In all, 76 patients with sinonasal malignant tumors.

FIELD STRENGTH/SEQUENCE

Fourteen different b values (b = 0, 50, 100, 150, 200, 250, 300, 350, 400, 800, 1000, 1500, 2000, and 2500 sec/mm² ) were used to perform different DWI models at 3.0T.

ASSESSMENT

The whole-tumor histogram metrics were calculated on the apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), diffusion kurtosis (K), and diffusion coefficient (Dk) maps. Histopathologic features, including nuclear, cytoplasmic, cellular, stromal fractions, and the nuclear-to-cytoplasmic (N/C) ratio, were measured.

STATISTICAL TESTS

Spearman correlations and stepwise multiple linear regression analyses were performed to determine the correlations between histogram metrics and histopathologic features.

RESULTS

ADC, Dk, and f histogram metrics showed significant correlations with investigated histopathologic features; D and K histogram metrics were significantly correlated with cellular, stromal, and nuclear fractions (all P < 0.05). Significant correlations between the 75th percentile of D and cytoplasmic fraction and between the kurtosis of K and the N/C ratio were observed (P < 0.05). The skewness of Dk, K, and the 75th percentile of D were independently associated with cellular and nuclear fractions; the skewness of Dk and K were independently associated with stromal fraction (P < 0.05).

DATA CONCLUSION

Monoexponential and advanced DWI histogram parameters were significantly correlated with histopathologic features in sinonasal malignancies.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:273-285.

Readout-segmented echo-planar diffusion-weighted MR at 3.0 T for the evaluation the effect of low-intensity transcranial ultrasound on stroke in a rat model

OBJECTIVE

To investigate the feasibility of the relative apparent diffusion coefficient (rADC) values based on readout-segmented echo-planar diffusion sequence in evaluation the effects of low-intensity transcranial ultrasound (LIPUS) on ischemic stroke in rat models at different onset times.

METHODS

Sixty Sprague-Dawley rats (weight, 250 ± 10 g) were divided randomly into six groups (n = 10) to establish a permanent model of distal middle cerebral artery occlusion (dMCAO). The rats were stimulated with ultrasound for 10 min in the LIPUS groups at 0.5 h, 1 h, 3 h, 6 h, and 9 h after dMCAO (denoted as the LIPUS group (0.5 h), LIPUS group (1 h), LIPUS group (3 h), LIPUS group (6 h), LIPUS group (9 h), and Control group without ultrasound stimulation). Magnetic resonance imaging was acquired at 0.5 h and 1 h after dMCAO and then at 1-hour intervals until 12 h. The rADC values were then measured and calculated. The pathological results from the rat brains were obtained after the experiment.

RESULTS

When LIPUS was applied 0.5 h after dMCAO, the rate of decline of rADC values in the early stages were significantly reduced and the final rADC values were significantly increased. When LIPUS were applied at 1 h, 3 h, and 6 h, the final rADC values only increased slightly and did not prevent early declines. No significant difference of ultrasound stimulation at 9 h was found.

CONCLUSION

The rADC values demonstrated difference at different time points after dMCAO between with and without LIPUS groups.

Benign and malignant skull-involved lesions: discriminative value of conventional CT and MRI combined with diffusion-weighted MRI

BACKGROUND

Little is known about the value of computed tomography (CT) and magnetic resonance imaging (MRI) combined with diffusion-weighted imaging (DWI) in distinguishing malignant from benign skull-involved lesions.

PURPOSE

To evaluate the discriminative value of DWI combined with conventional CT and MRI for differentiating between benign and malignant skull-involved lesions.

MATERIAL AND METHODS

CT and MRI findings of 58 patients with pathologically proven skull-involved lesions (43 benign and 15 malignant) were retrospectively reviewed. Conventional CT and MRI characteristics and apparent diffusion coefficient (ADC) value of the two groups were evaluated and compared. Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses were performed to assess the differential performance of each parameter separately and together.

RESULTS

The presence of cortical defects or break-through and ill-defined margins were associated with malignant skull-involved lesions (both P < 0.05). Malignant skull-involved lesions demonstrated a significantly lower ADC (P = 0.016) than benign lesions. ROC curve analyses indicated that a combination of CT, MRI, and DWI with an ADC ≤ 0.703 × 10^-3 mm²/s showed optimal sensitivity, while DWI along showed optimal specificity of 88.4% in differentiating between benign and malignant skull-involved lesions.

CONCLUSION

The combination of CT, MRI, and DWI can help to differentiate malignant from benign skull-involved lesions. CT + MRI + DWI offers optimal sensitivity, while DWI offers optimal specificity.

Application of diffusion-weighted MR imaging with ADC measurement for distinguishing between the histopathological types of sinonasal neoplasms

PURPOSE

To evaluate the potential contribution of quantitative DWI parameters including ADC_mean and ADC_ratio values to help in distinguishing the histopathological types of sinonasal neoplasms.

METHODS

This retrospective study included 83 patients (50 males, 33 females; mean age 61 years) with pathologically proven untreated sinonasal neoplasms who have undergone diffusion-weighted MRI imaging from February 2010 to August 2017. Diffusion-weighted MRI was performed on a 3 T unit with b factors of 0 and 1000 s/mm², and ADC maps were generated. Mean ADC values of sinonasal tumors and ADC ratios (ADC_mean of the tumor to ADC_mean of pterygoid muscles) were compared with the histopathological diagnosis by utilizing the Kruskal-Wallis non-parametric test.

RESULTS

Mean ADC_mean and ADC_ratio were 0.8 (SD, ±0.4) × (10^-3 mm²/s) and 1.2 (SD, ±0.5), respectively, and each parameter was significantly different between histopathological types (p < 0.05). Mean ADC_mean and ADC_ratio were higher in adenoid cystic carcinoma (ACC) than in SCC, lymphoma, neuroendocrine carcinoma and sinonasal undifferentiated carcinoma (SNUC) (p < 0.05). Optimized ADC_mean thresholds of 0.79, 0.81, 0.74 and 0.78 (10^-3 mm²/s) achieved maximal discriminatory accuracies of 100%, 79%, 100% and 89% for ACC/SNUC, ACC/SCC, ACC/neuroendocrine carcinoma, and ACC/lymphoma, respectively.

CONCLUSIONS

The optimized ADC_mean threshold of 0.80 (10^-3 mm²/s) could be used to differentiate ACC from non-ACC sinonasal neoplasms with maximal discriminatory accuracy (82%) and sensitivity of 100%. However, there is considerable overlapping of the ADC_mean and ADC_ratio values among non-ACC sinonasal neoplasms hence surgical biopsy is still needed.

Feasibility of Intravoxel Incoherent Motion for Differentiating Benign and Malignant Thyroid Nodules

RATIONALE AND OBJECTIVES

This study aimed to preliminarily investigate the feasibility of intravoxel incoherent motion (IVIM) theory in the differential diagnosis of benign and malignant thyroid nodules.

MATERIALS AND METHODS

Forty-five patients with 56 confirmed thyroid nodules underwent preoperative routine magnetic resonance imaging and IVIM diffusion-weighted imaging. The histopathologic diagnosis was confirmed by surgery. Apparent diffusion coefficient (ADC), perfusion fraction f, diffusivity D, and pseudo-diffusivity D* were quantified. Independent samples t test of IVIM-derived metrics were conducted between benign and malignant nodules. Receiver-operating characteristic analyses were performed to determine the optimal thresholds as well as the sensitivity and specificity for differentiating.

RESULTS

Significant intergroup difference was observed in ADC, D, D*, and f (p < 0.001). Malignant tumors featured significantly lower ADC, D and D* values and a higher f value than that of benign nodules. The ADC, D, and D* could distinguish the benign from malignant thyroid nodules, and parameter f differentiate the malignant tumors from benign nodules. The values of the area under the curve for parameter ADC, D, and D* were 0.784 (p = 0.001), 0.795 (p = 0.001), and 0.850 (p < 0.001), separately, of which the area under the curve of f value was the maximum for identifying the malignant from benign nodules, which was 0.841 (p < 0.001).

CONCLUSION

This study suggested that ADC and IVIM-derived metrics, including D, D*, and f, could potentially serve as noninvasive predictors for the preoperative differentiating of thyroid nodules, and f value performed best in identifying the malignant from benign nodules among these parameters.

Correlation between tumor glucose metabolism and multiparametric functional MRI (IVIM and R2*) metrics in cervical carcinoma: Evidence from integrated 18 F-FDG PET/MR

BACKGROUND

Multiparameter, multimodality ¹⁸ F-FDG PET/MRI holds great potential for the diagnosis of cervical cancer based on the correlation between tumor glucose metabolism and imaging parameters.

PURPOSE

To characterize the heterogeneity of tumor glucose metabolism by evaluating the correlation between ¹⁸ F-FDG uptake parameters and multiparametric functional MRI metrics in cervical carcinoma.

STUDY TYPE

Retrospective.

POPULATION

Fifty-four patients with cervical carcinoma.

FIELD STRENGTH/SEQUENCE

Hybrid PET/MR (3T), multi-b DWI, and R2* mapping.

ASSESSMENT

The maximum and mean standardized uptake values (SUV_max and SUV_mean , respectively) from PET and functional MRI metrics (D, D*, f, and R2*) were obtained. Cervical carcinoma tissues also underwent HIF-1α, VEGF, and GLUT-1 immunohistochemical staining.

STATISTICAL TESTS

Single-factor Spearman rank and Pearson correlation analysis and multiple linear regression (MLR) analysis were applied.

RESULTS

R2*, D, and f have different degrees of correlation (moderate, weak, moderately strong correlation, respectively) with SUV_max and SUV_mean (r = 0.530 and 0.527, and P < 0.001 for R2*; r = -0.292 and -0.291, and P < 0.05 for D; r = 0.539 and 0.520, and P < 0.001 for f, respectively). Immunohistochemical staining showed that HIF-1α expression has a moderate degree of correlation with R2* (r = 0.491; P < 0.001); GLUT-1 expression was significantly correlated with SUV_max and SUV_mean (r = 0.633 and 0.622; P < 0.001), and VEGF expression had a moderately strong correlation with f (r = 0.457; P = 0.001). If SUV_max is the dependent variable, MLR yields an R-squared value after adjustment (adjusted R-squared) = 0.358, and F = 10.833 (P < 0.001), and the fitting linear equation is Y (SUV_max ) = 9.184 + 0.161X1 (R2*)+50.343X2 (f)-4.780 (D). Otherwise, MLR yields the adjusted R-squared = 0.342, and F = 10.187 (P < 0.001), and the linear regression equation is Y (SUV_mean ) = 5.925 + 0.102X1 (R2*)+28.029X2 (f)-2.907X3 (D).

DATA CONCLUSION

The functional MRI sequence parameters R2*, f, and D can provide information on the hypoxic condition, blood perfusion, and molecular diffusion of the tumor. ¹⁸ F-FDG PET/MR multi-imaging technique can be adopted to evaluate the heterogeneity of glucose metabolism in cervical carcinoma.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:1704-1712.

Quantitative diffusion magnetic resonance imaging in head and neck tumors

In patients with head and neck cancer, conventional anatomical magnetic resonance imaging (MRI) scans are commonly used for identification of primary lesion, assessment of structural distortion, and presence of metastatic lymph nodes. However, quantitative analysis of diffusion MRI can provide added value to structural and anatomical evaluation of head and neck tumors (HNT), by differentiation of primary malignant process, prognostic prediction, and treatment monitoring. In this article, we will review the applications of quantitative diffusion MRI in identification of primary malignant tissue, differentiation of tumor pathology, prediction of molecular phenotype, monitoring of treatment response, and evaluation of posttreatment changes in patient with HNT.

Intravoxel Incoherent Motion Diffusion-weighted MR Imaging for Early Evaluation of the Effect of Radiofrequency Ablation in Rabbit Liver VX2 Tumors

RATIONALE AND OBJECTIVES

This study aims to investigate the value of intravoxel incoherent motion (IVIM)-derived parameters for early evaluation of the efficiency of radiofrequency ablation (RFA) treatment for rabbit liver VX2 tumor.

MATERIALS AND METHODS

Eighteen rabbit liver VX2 tumor models were constructed, and computed tomography-guided RFA was performed. One day before and 7 days after RFA, 18 models underwent magnetic resonance imaging, including contrast-enhanced imaging and IVIM diffusion-weighted imaging with 16 b-factors (0-1000 s/mm²). Post-RFA liver tumors were segmented into viable tumor, inflammatory reaction, and ablation necrotic regions according to gross and histopathologic examinations. Parameters derived from IVIM were calculated. One-way analysis of variance and least significant difference test were used for comparisons among the three regions. The diagnostic performance of parameters was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

ADC_total, D, and f values were significantly lower in viable tumor than in inflammatory reaction regions (all P < .05), but D* showed no significant difference between the two regions. ADC_total values of viable tumor regions were significantly lower than that of ablation necrotic regions (P = .007), but D* values of necrotic regions were significantly lower than that of viable tumor regions (P = .045). In ROC analysis, ADC showed the highest area under the ROC curve for differentiating inflammatory reaction from viable tumor region.

CONCLUSIONS

ADC_total, D, and f were valuable discriminating markers for differentiation between regions of viable tumor and inflammatory reaction in post-RFA tumor, especially ADC_total outperformed the other two parameters with higher diagnostic performance.

Histogram analysis parameters of apparent diffusion coefficient reflect tumor cellularity and proliferation activity in head and neck squamous cell carcinoma

Our purpose was to analyze associations between apparent diffusion coefficient (ADC) histogram analysis parameters and histopathologicalfeatures in head and neck squamous cell carcinoma (HNSCC).

The study involved 32 patients with primary HNSCC. For every tumor, the following histogram analysis parameters were calculated: ADCmean, ADCmax, ADC_min, ADC_median, ADC_mode, P10, P25, P75, P90, kurtosis, skewness, and entropy. Furthermore, proliferation index KI 67, cell count, total and average nucleic areas were estimated. Spearman's correlation coefficient (p) was used to analyze associations between investigated parameters.

In overall sample, all ADC values showed moderate inverse correlations with KI 67. All ADC values except ADCmax correlated inversely with tumor cellularity. Slightly correlations were identified between total/average nucleic area and ADC_mean, ADC_min, ADC_median, and P25.

In G1/2 tumors, only ADCmode correlated well with Ki67. No statistically significant correlations between ADC parameters and cellularity were found.

In G3 tumors, Ki 67 correlated with all ADC parameters except ADCmode. Cell count correlated well with all ADC parameters except ADCmax. Total nucleic area correlated inversely with ADC_mean, ADC_min, ADC_median, P25, and P90.

ADC histogram parameters reflect proliferation potential and cellularity in HNSCC. The associations between histopathology and imaging depend on tumor grading.

Can Imaging Parameters Provide Information Regarding Histopathology in Head and Neck Squamous Cell Carcinoma? A Meta-Analysis

OBJECT

Our purpose was to provide data regarding relationships between different imaging and histopathological parameters in HNSCC.

METHODS

MEDLINE library was screened for associations between different imaging parameters and histopathological features in HNSCC up to December 2017. Only papers containing correlation coefficients between different imaging parameters and histopathological findings were acquired for the analysis.

RESULTS

Associations between ¹⁸F-FDG positron emission tomography (PET) and KI 67 were reported in 8 studies (236 patients). The pooled correlation coefficient was 0.20 (95% CI = [-0.04; 0.44]). Furthermore, in 4 studies (64 patients), associations between ¹⁸F-fluorothymidine PET and KI 67 were analyzed. The pooled correlation coefficient between SUV_max and KI 67 was 0.28 (95% CI = [-0.06; 0.94]). In 2 studies (23 patients), relationships between KI 67 and dynamic contrast-enhanced magnetic resonance imaging were reported. The pooled correlation coefficient between K_trans and KI 67 was -0.68 (95% CI = [-0.91; -0.44]). Two studies (31 patients) investigated correlation between apparent diffusion coefficient (ADC) and KI 67. The pooled correlation coefficient was -0.61 (95% CI = [-0.84; -0.38]). In 2 studies (117 patients), relationships between ¹⁸F-FDG PET and p53 were analyzed. The pooled correlation coefficient was 0.0 (95% CI = [-0.87; 0.88]). There were 3 studies (48 patients) that investigated associations between ADC and tumor cell count in HNSCC. The pooled correlation coefficient was -0.53 (95% CI = [-0.74; -0.32]). Associations between ¹⁸F-FDG PET and HIF-1α were investigated in 3 studies (72 patients). The pooled correlation coefficient was 0.44 (95% CI = [-0.20; 1.08]).

CONCLUSIONS

ADC may predict cell count and proliferation activity, and SUV_max may predict expression of HIF-1α in HNSCC. SUV_max cannot be used as surrogate marker for expression of KI 67 and p53.

Intravoxel Incoherent Motion MR Imaging in the Differentiation of Benign and Malignant Sinonasal Lesions: Comparison with Conventional Diffusion-Weighted MR Imaging

BACKGROUND AND PURPOSE

Intravoxel incoherent motion is a promising method for the differentiation of sinonasal lesions. This study aimed to evaluate the value of intravoxel incoherent motion in the differentiation of benign and malignant sinonasal lesions and to compare the diagnostic performance of intravoxel incoherent motion with that of conventional DWI.

MATERIALS AND METHODS

One hundred thirty-one patients with histologically proved solid sinonasal lesions (56 benign and 75 malignant) who underwent conventional DWI and intravoxel incoherent motion were recruited in this study. The diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) values derived from intravoxel incoherent motion and ADC values derived from conventional DWI were measured and compared between the 2 groups using the Student t test. Receiver operating characteristic curve analysis, logistic regression analysis, and 10-fold cross-validation were performed to evaluate the diagnostic performance of single-parametric and multiparametric models.

RESULTS

The mean ADC and D values were significantly lower in malignant sinonasal lesions than in benign sinonasal lesions (both P < .001). The mean f value was higher in malignant lesions than in benign lesions (P = .003). Multiparametric models can significantly improve the cross-validated areas under the curve for the differentiation of sinonasal lesions compared with single-parametric models (all corrected P < .05 except the D value). The model of D+f provided a better diagnostic performance than the ADC value (corrected P < .001).

CONCLUSIONS

Intravoxel incoherent motion appears to be a more effective MR imaging technique than conventional DWI in the differentiation of benign and malignant sinonasal lesions.

To predict the radiosensitivity of nasopharyngeal carcinoma using intravoxel incoherent motion MRI at 3.0 T

PURPOSE

To investigate intravoxel incoherent motion (IVIM) MRI for evaluating the sensitivity of radiotherapy on nasopharyngeal carcinoma (NPC).

RESULTS

The reproducibility between intra-observer and inter-observer was relatively good. D (0.72×10^-3 mm²/s±0.14 vs. 0.54×10^-3 mm²/s±0.23; P < 0.001) and D* (157.92×10^-3 mm²/s±15.21 vs. 120.36×10^-3 mm²/s±10.22; P < 0.0001) were significantly higher in effective group than poor-effective group, whereas the difference of f (18.79%±2.51 vs. 16.47%±1.51) and ADC (1.21×10^-3 mm²/s±0.11 vs. 1.33×10^-3 mm²/s±0.23) could not reach statistical significant between the 2 groups (P > 0.05).

CONCLUSIONS

IVIM may be potentially useful in assessing the radiosensitivity of NPC. The higher D value combining with higher D* value might indicate the more radiosensitive of NPC, and increased D* might reflect increased blood vessel generation and parenchymal perfusion in NPC.

MATERIALS AND METHODS

Sixty consecutive patients (20 female, range, 27-83 years, mean age, 52 years) newly diagnosed NPC in the stage of T3 or T4 were enrolled. Forty-two of them were divided into effective group clinically after a standard radiotherapy according to the RECIST criteria. IVIM with 13 b-values (range, 0-800 s/mm²) and general MRI were performed at 3.0T MR scanner before and after radiotherapy. The parameters of IVIM including perfusion fraction (f), perfusion-related diffusion (D*), pure molecular diffusion (D) and apparent diffusion coefficient (ADC) were calculated. Two radiologists major in MRI diagnose analyzed all images independently and placed regions of interest (ROIs). Intra-class correlation coefficient (ICC) was used to evaluate intra-observer and inter-observer agreement. And Mann-Whitney test was used to assess the differences between the two groups.

Can Diffusion Weighted Imaging Aid in Differentiating Benign from Malignant Sinonasal Masses?: A Useful Adjunct

Background

To evaluate the role of diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) values at 3 Tesla in characterizing sinonasal masses.

Material/Methods

After ethical clearance, 79 treatment naive patients with head and neck masses underwent magnetic resonance imaging (MRI), including DWI at 3 Tesla using the following b values – 0, 500 and 1000 s/mm². Thirty-one patients were found to have sinonasal tumours and were subsequently analysed. Image analysis consisted of a morphological evaluation of conventional MR images, qualitative evaluation of DW trace images and quantitative assessment of mean ADC values. Receiver operating characteristic (ROC) curve was drawn to determine a cut-off ADC value for the differentiation between benign and malignant masses.

Results

Sinonasal masses showed an overlapping growth pattern on conventional imaging, irrespective of their biological nature. The mean ADC value of benign lesions was 1.948±0.459×10⁻³ mm²/s, while that of malignant lesions was 1.046±0.711×10⁻³ mm²/s, and the difference was statistically significant (p=0.004). When a cut-off ADC value of 1.791×10⁻³ mm²/s was used, sensitivity of 80% and specificity of 83.3% were obtained for characterization of malignant lesions, which was statistically significant. Juvenile nasopharyngeal angiofibroma (JNA) showed distinctly high ADC values, while meningioma was the only benign lesion with restricted diffusion. Atypical entities with unexpected diffusion characteristics included: adenocarcinoma, adenoid cystic carcinoma, meningioma, chondrosarcoma and fibromyxoid sarcoma.

Conclusions

DWI in conjunction with conventional imaging can potentially enhance the diagnostic accuracy in characterizing sinonasal masses as benign or malignant. Some specific entities such as JNA and meningioma showed distinctive diffusion characteristics.

Correlation between apparent diffusion coefficient (ADC) and cellularity is different in several tumors: a meta-analysis

The purpose of this meta-analysis was to provide clinical evidence regarding relationship between ADC and cellularity in different tumors based on large patient data.

Medline library was screened for associations between ADC and cell count in different tumors up to September 2016. Only publications in English were extracted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA) was used for the research.

Overall, 39 publications with 1530 patients were included into the analysis. The following data were extracted from the literature: authors, year of publication, number of patients, tumor type, and correlation coefficients.

The pooled correlation coefficient for all studies was ρ = -0.56 (95 % CI = [−0.62; −0.50]),. Correlation coefficients ranged from ρ =−0.25 (95 % CI = [−0.63; 0.12]) in lymphoma to ρ=−0.66 (95 % CI = [−0.85; −0.47]) in glioma. Other coefficients were as follows: ovarian cancer, ρ = −0.64 (95% CI = [−0.76; −0.52]); lung cancer, ρ = −0.63 (95 % CI = [−0.78; −0.48]); uterine cervical cancer, ρ = −0.57 (95 % CI = [−0.80; −0.34]); prostatic cancer, ρ = −0.56 (95 % CI = [−0.69; −0.42]); renal cell carcinoma, ρ = −0.53 (95 % CI = [−0.93; −0.13]); head and neck squamous cell carcinoma, ρ = −0.53 (95 % CI = [-0.74; −0.32]); breast cancer, ρ = −0.48 (95 % CI = [−0.74; −0.23]); and meningioma, ρ = -0.45 (95 % CI = [−0.73; −0.17]).

The Added Value of Diffusion Magnetic Resonance Imaging in the Diagnosis and Posttreatment Evaluation of Skull Base Chordomas

Objectives  To determine the use of diffusion-weighted imaging (DWI) in the pre- and posttreatment evaluation of skull base chordomas. Design  Retrospective study. Setting  Tertiary care university hospital. Participants  In total, 17 patients with histopathological diagnosis of chordoma who had magnetic resonance (MR) imaging and DWI were evaluated. Of them, 13 patients had posttreatment MR imaging including DWI. Main Outcome Measures  Three apparent diffusion coefficient (ADC) values were obtained from tumor, and an ADC value was measured from pons for the purpose of normalization. ADC values of the subtypes of chordomas (typical and chondroid chordomas) were compared. Results  Ten (59%) masses had increased signal on trace DWI at pretreatment evaluation. The mean ADC _{entire tumor} /ADC _pons was calculated as 1.55 ± 0.44. The mean ADC _{entire tumor} values of typical and chondroid chordomas were 1.26 ± 0.29 × 10 ^-3 mm ² /s and 0.99 ± 0.46 × 10 ^-3 mm ² /s, respectively. There was no statistically significant difference between ADC values of the subtypes ( p  > 0.05). For posttreatment evaluation, DWI enabled detection of residual tumor in the majority (85%) of cases. Conclusions  DWI is useful in diagnosis and posttreatment evaluation of skull base chordomas. However, ADC values in our series did not distinguish the subtypes of chordomas.

Differentiating Benign from Malignant Sinonasal Lesions: Feasibility of Diffusion Weighted MRI

Introduction  Appearance of nasal masses on routine CT and MRI are not pathognomonic. We utilized the apparent diffusion coefficient (ADC) value obtained from diffusion weighted image (DWI) to detect the differences in the microstructures of tumor and non-tumor tissues.

Objective  The objective of our study was to evaluate the diagnostic role of DWI and ADC values in differentiating between malignant and benign sinonasal lesions and its correlation with histopathological results as the reference standard.

Methods  Patients with nasal and / or paranasal mass underwent CT, MRI, and DWI before any surgical intervention. We used diagnostic sinonasal endoscopy and biopsy to confirm the diagnosis after MRI.

Results  When we used ADC value of (1.2 × 10–3 mm2/s) as a cut-off value for differentiating benign from malignant sinonasal lesions, we achieved 90% accuracy, 100% sensitivity, 88.4% specificity, 77.8% positive predictive value, and 100% negative predictive value. At this cut-off, benign lesions show statistically significant higher ADC value than malignant tumors.

Conclusion  DW MRI and ADC value calculation are promising quantitative methods helping to differentiate between malignant and benign sinonasal lesions. Thus, they are effective methods compared with other conventional methods with short imaging time thus it is recommended to be incorporated into routine evaluations.

Diffusion kurtosis imaging for differentiating between the benign and malignant sinonasal lesions

PURPOSE

The study aimed to evaluate diffusion kurtosis imaging (DKI) in the differentiation between benign and malignant sinonasal lesions, and to compare the diagnostic performance of DKI with diffusion weighted imaging (DWI).

MATERIALS AND METHODS

Eight-one patients with solid sinonasal lesions confirmed by surgery and pathology (46 malignant and 35 benign) underwent conventional MRI, DWI, and DKI. DKI was performed employing a 13 extended b-value ranging from 0 to 2500 s/mm² . Apparent diffusion coefficient (ADC) from DWI, kurtosis (K), and diffusion coefficient (D) from DKI were measured and compared between two groups.

RESULTS

ADC and D values were significantly lower in the malignant sinonasal lesions than in the benign sinonasal lesions (1.11 ± 0.41 versus 1.58 ± 0.50 × 10^-3 mm² /s and 1.45 ± 0.36 versus 2.03 ± 0.49 × 10^-3 mm² /s, respectively, both P < 0001). K value was significantly higher in the malignant lesions than in the benign lesions (0.91 ± 0.23 versus 0.57 ± 0.24, P < 0001). The receiver operating characteristic curve analyses yielded a cutoff ADC value of 1.27 × 10^-3 mm² /s for differentiating between benign and malignant lesions, with a sensitivity of 69.6%, a specificity of 77.1% and an accuracy of 74.0%; a cutoff D value of 1.75 × 10^-3 mm² /s, with a sensitivity of 82.6%, a specificity of 77.1% and an accuracy of 80.2%; a cutoff K value of 0.63 with a sensitivity of 95.7%, a specificity of 77.1% and an accuracy of 87.7%. The area under the curve of K value was significantly larger than that of ADC value (0.875 versus 0.762; P < 0.05).

CONCLUSION

K value of DKI demonstrates significantly higher accuracy compared with ADC value for the differentiation between benign and malignant sinonasal lesions. DKI may be a noninvasive method to evaluate the sinonasal lesions.

LEVEL OF EVIDENCE

1 J. MAGN. RESON. IMAGING 2017;45:1446-1454.

Intravoxel Incoherent Motion Diffusion Weighted Magnetic Resonance Imaging for Differentiation Between Nasopharyngeal Carcinoma and Lymphoma at the Primary Site

OBJECTIVE

The aim of the study was to investigate the utility of intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (DWI) for differentiating nasopharyngeal carcinoma (NPC) from lymphoma.

METHODS

Intravoxel incoherent motion-based parameters including the apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), and fD* (the product of D* and f) were retrospectively compared between 102 patients (82 with NPC, 20 with lymphoma) who received pretreatment IVIM DWI.

RESULTS

Compared with lymphoma, NPC exhibited higher ADC, D, D*, fD* values (P < 0.001) and f value (P = 0.047). The optimal cutoff values (area under the curve, sensitivity, and specificity, respectively) for distinguishing the 2 tumors were as follows: ADC value of 0.761 × 10 mm/s (0.781, 93.90%, 55.00%); D, 0.66 × 10 mm/s (0.802, 54.88%, 100.00%); D*, 7.89 × 10 mm/s (0.898, 82.93%, 85.00%); f, 0.29 (0.644, 41.46%, 95.00%); and fD*, 1.99 × 10 mm/s (0.960, 85.37%, 100.00%).

CONCLUSIONS

Nasopharyngeal carcinoma exhibits different IVIM-based imaging features from lymphoma. Intravoxel incoherent motion DWI is useful for differentiating lymphoma from NPC.

Discrimination between Metastatic and Nonmetastatic Mesorectal Lymph Nodes in Rectal Cancer Using Intravoxel Incoherent Motion Diffusion-weighted Magnetic Resonance Imaging

RATIONALE AND OBJECTIVES

The aim of the study was to investigate the diagnostic value of intravoxel incoherent motion diffusion-weighted magnetic resonance imaging (IVIM DWI) for discriminating nonmetastatic from metastatic mesorectal lymph nodes in rectal cancer.

MATERIALS AND METHODS

IVIM DWI was performed preoperatively on 50 patients with rectal carcinoma. The short-axis diameter, short- to long-axis diameter ratio, and IVIM-based parameter (pure diffusion coefficient [D], pseudo-diffusion coefficient [D*] and perfusion fraction [f]) values were compared between the metastatic and nonmetastatic lymph node groups.

RESULTS

The short-axis diameter; short- to long-axis diameter ratio; and D, D*, and f values for the nonmetastatic lymph node group (n = 28) were 6.446 ± 1.201 mm, 0.815 ± 0.099, 1.071 ± 0.234 × 10(-3) mm(2)/s, 15.443 ± 5.946 mm(2)/s and 0.261 ± 0.128, respectively, and were 9.045 ± 3.185 mm, 0.809 ± 0.099, 0.816 ± 0.121 × 10(-3) mm(2)/s, 11.679 ± 7.521 × 10(-3) mm(2)/s, and 0.190 ± 0.064, respectively, for the metastatic lymph node group (n = 31). The short-axis diameter for the metastatic group was significantly higher than for the nonmetastatic group (P <0.001). The metastatic group exhibited significantly lower D and D* values than the nonmetastatic group (P <0.01). The short- to long-axis diameter ratio and f values did not differ significantly between the two groups. Optimal cutoff values (area under the curve, sensitivity, and specificity) for distinguishing metastatic from nonmetastatic lymph nodes were as follows: short-axis diameter = 5.563 mm (0.783, 74.2%, 82.1%); D = 0.667 × 10(-3) mm(2)/s (0.885, 77.4%, 89.3%); and D* = 0.485 × 10(-3) mm(2)/s (0.727, 80.6%, 67.9%).

CONCLUSION

IVIM DWI is useful to differentiate between metastatic and nonmetastatic mesorectal lymph nodes in rectal cancer.

Readout-segmented echo-planar imaging in the evaluation of sinonasal lesions: A comprehensive comparison of image quality in single-shot echo-planar imaging

PURPOSE

To investigate the role of readout-segmented echo-planar imaging using parallel imaging and a two-dimensional (2D) navigator (RESOLVE) in the evaluation of sinonasal lesions and to qualitatively and quantitatively compare the image qualities of single-shot echo-planar imaging (SS-EPI) and RESOLVE.

MATERIALS AND METHODS

Both sinonasal SS-EPI and RESOLVE images were acquired from 32 patients on a 3-T MR scanner. Image quality, lesion conspicuity and the distortions of the SS-EPI and RESOLVE images were qualitatively evaluated by two radiologists. Distortion was also quantitatively evaluated by comparing the distances between the same anatomic points on TSE-T1WI, TSE-T2WI, SS-EPI and RESOLVE images. The apparent diffusion coefficient (ADC) values, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) of the two DWIs were compared.

RESULTS

The comparisons of the qualitative scores indicated that RESOLVE significantly improved the image quality and lesion conspicuity and reduced the distortion of the sinonasal diseases. The orbit, skull base, temporal bone and upper neck were also better displayed on RESOLVE. Quantitative evaluations revealed that RESOLVE greatly reduced but did not completely remove the distortion. The ADC values of the sinonasal lesions on RESOLVE were lower than those on SS-EPI, whereas no differences were found in the brainstem. The SNR of RESOLVE was lower than that of SS-EPI. There were no differences in the CNRs of the two diffusion-weighted imaging (DWI) techniques.

CONCLUSION

RESOLVE significantly improved the image quality for evaluations of sinonasal lesions by reducing the susceptibility artifacts, distortion and blurring compared with SS-EPI. RESOVLE offers more accurate ADC values of sinonasal lesions than SS-EPI.

Utility of apparent diffusion coefficient in characterization of different sinonasal pathologies

BACKGROUND

Sinonasal lesions are a heterogeneous group of lesions that span from a tumor to tumor-like nature. Characterization of such cases preoperatively can improve the surgical control and the overall outcome of these patients.

OBJECTIVE

In this prospective study, we aimed at evaluation of the role of apparent diffusion coefficient (ADC) in the differentiation between benign and malignant sinonasal lesions.

SUBJECTS AND METHODS

All patients scheduled to have sinonasal surgical intervention at Ain Shams University Hospitals, Cairo, Egypt, were enrolled. Diffusion-weighted (DW) magnetic resonance imaging (MRI) with calculation of ADC were done for all cases. Radiologic findings were then compared with histologic findings, and the sensitivity, specificity, negative and positive predictive values (PPVs) of the conventional MRI, DW-MRI, and ADC value in differentiation of benign from malignant sinonasal lesions were then calculated.

RESULTS

There were 59 patients with median age of 43 years old. There were 20 cases of inflammatory lesions, 16 cases of benign tumors, and 23 cases of malignant lesions. The ADC values of all cases ranged from 0.4 × 10(-3) to 2 × 10(-3) (median = 1.5 × 10(-3)). The median ADC value for the malignant lesions was 0.6 × 10(-3), whereas that for the inflammatory conditions was 1.6 × 10(-3) and that for the benign tumors was 1.5 × 10(-3) with a highly significant difference (p < .001). Analysis of the conventional MRI and DW-MRI to differentiate between malignant and benign lesions showed that the sensitivity, specificity, PPV, and negative predictive value (NPV) were 100%, 97%, 96%, and 100% and 91%, 97%, 95%, and 95%, respectively.

CONCLUSION

DW-MRI did not add significantly to the information gained from conventional MRI. It should be considered complimentary only to standard MRI in uncertain cases when malignancy is still a concern.

Differentiation of extranodal non-Hodgkins lymphoma from squamous cell carcinoma of the maxillary sinus: a multimodality imaging approach

This study aimed to assess the efficacy of a multimodality imaging approach for differentiating between primary extranodal non-Hodgkin’s lymphoma (NHL) and squamous cell carcinoma (SCC) of the maxillary sinus. Twelve NHLs and 29 SCCs of the maxillary sinus were included. CT findings, MR signal intensities, apparent diffusion coefficients (ADCs), and maximum standardized uptake values (SUVmax) were correlated with two pathologies. On CT, permeative growth frequency was greater among NHLs than among SCCs (50 % vs. 10 %; p < 0.01), whereas destructive growth frequency was greater among SCCs than among NHLs (83 % vs. 33 %; p < 0.01). On CT, remaining sinus wall within the tumor was more frequent with NHLs than with SCCs (92 % vs. 34 %; p < 0.01), whereas intratumoral necrosis was more frequent with SCCs than with NHLs (86 % vs. 17 %; p < 0.01). ADCs were lower for NHLs than for SCCs (0.61 vs. 0.95 × 10^–3 mm²/s; p < 0.01). No significant differences in MR signal intensities and SUVmax were observed. Tumor growth pattern, remaining sinus wall within the tumor, and intratumoral necrosis were useful CT findings for differentiating between NHLs and SCCs. ADC measurements could assist the differentiation of NHL from SCC.

The role of diffusion-weighted magnetic resonance imaging in the diagnosis, lymph node staging and assessment of treatment response of head and neck cancer

Standard magnetic resonance imaging (MRI) and computed tomography continue to be the imaging modalities of choice in staging and reviewing patients with head and neck cancer. Diffusion-weighted MRI (DW-MRI) is an advanced imaging modality that records the molecular diffusion of protons and thus provides an opportunity to further assess tissue character. Interest in DW-MRI of the head and neck continues to grow, especially its application to the assessment and treatment of head and neck cancer. We highlight the potential role of DW-MRI in the delineation, characterization, and lymph node staging of head and neck tumours. Furthermore, we discuss the ability of DW-MRI to provide a real opportunity to differentiate post-treatment tumour recurrence from chemoradiotherapy-induced local tissue changes. The future impact of these findings upon the clinical practice of the head and neck surgeon is discussed.

The role of 3 Tesla diffusion-weighted imaging in the differential diagnosis of benign versus malignant cervical lymph nodes in patients with head and neck squamous cell carcinoma

OBJECTIVE

The aim of this study was to validate the role of diffusion-weighted imaging (DWI) at 3 Tesla in the differential diagnosis between benign and malignant laterocervical lymph nodes in patients with head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Before undergoing surgery, 80 patients, with biopsy proven HNSCC, underwent a magnetic resonance exam. Sensitivity (Se) and specificity (Spe) of conventional criteria and DWI in detecting laterocervical lymph node metastases were calculated. Histological results from neck dissection were used as standard of reference.

RESULTS

In the 239 histologically proven metastatic lymphadenopathies, the mean apparent diffusion coefficient (ADC) value was 0.903 × 10(-3) mm(2)/sec. In the 412 pathologically confirmed benign lymph nodes, an average ADC value of 1.650 × 10(-3) mm(2)/sec was found. For differentiating between benign versus metastatic lymph nodes, DWI showed Se of 97% and Spe of 93%, whereas morphological criteria displayed Se of 61% and Spe of 98%. DWI showed an area under the ROC curve (AUC) of 0.964, while morphological criteria displayed an AUC of 0.715.

CONCLUSIONS

In a DWI negative neck for malignant lymph nodes, the planned dissection could be converted to a wait-and-scan policy, whereas DWI positive neck would support the decision to perform a neck dissection.

Intravoxel incoherent motion MRI: emerging applications for nasopharyngeal carcinoma at the primary site

Objectives

We compared pure molecular diffusion (D), perfusion-related diffusion (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC) based on intravoxel incoherent motion (IVIM) theory in patients with nasopharyngeal carcinoma (NPC).

Methods

Sixty-five consecutive patients (48 men) with suspected NPC were examined using a 3.0-T MR system. Diffusion-weighted imaging (DWI) was performed with 13 b values (range, 0–800 s/mm²). We regarded the result of endoscopy and biopsy as the gold standard for detection. D, D* and f were compared between patients with primary NPC and enlarged adenoids.

Results

IVIM DWI was successful in 37 of 40 NPC and 23 of 25 enlarged adenoids cases. D (P = 0.001) and f (P < 0.0001) were significantly lower in patients with NPC than in patients with enlarged adenoids, whereas D* was significantly higher (P < 0.0001). However, the ADC was not significantly different between the two groups (P > 0.05). The area under the ROC curve (AUC) for D was 0.849 and was significantly larger than that for ADC (P < 0.05).

Conclusions

IVIM DWI is a feasible technique for investigating primary NPC. D was significantly decreased in primary NPC, and increased D* reflected increased blood vessel generation and parenchymal perfusion in primary NPC.

Key Points

• Intravoxel incoherent motion (IVIM) analysis permits separate quantification of diffusion and perfusion.

• IVIM DWI is a feasible technique for investigating primary NPC.

• IVIM suggests that primary NPC tissue voxels exhibit both perfusion and diffusion.

Diffusion-weighted imaging for differentiating benign from malignant skull lesions and correlation with cell density

OBJECTIVE

The objective of our study was to determine the utility of diffusion-weighted imaging (DWI) and cell density for differentiating benign from malignant skull lesions.

MATERIALS AND METHODS

A retrospective review was performed. Minimum apparent diffusion coefficient (ADC) values were measured and normalized to white matter, which we refer to as "normalized ADC," in 24 skull lesions (12 malignant and 12 benign) in 18 patients. In addition, cell densities were measured in 15 cases and correlated with ADC values.

RESULTS

The average minimum ADC in malignant tumors was 0.70 × 10(-3) mm(2)/s versus 1.11 × 10(-3) mm(2)/s in benign tumors (p = 0.0037). Similarly, the average normalized ADC for malignant tumors was 1.03, whereas the average normalized ADC for benign tumors was 1.65 (p = 0.0012). Receiver operating characteristic curve analysis yielded optimal normalized ADC and ADC thresholds of 1.23 (accuracy, 84.6%; sensitivity, 75.0%; specificity, 92.3%) and 1.01 × 10(-3) mm(2)/s (accuracy, 83.7%; sensitivity, 83.3%; specificity, 84.6%), respectively. There was a significant inverse correlation between cell density and normalized ADC (r = -0.58; p = 0.023). The low cellularity in chordoma and low-grade chondrosarcoma and high cellularity in eosinophilic granuloma may explain the DWI features of these lesions.

CONCLUSION

ADC values in skull lesions correlate with cell density and can potentially narrow the differential diagnoses for indeterminate skull lesions. Understanding the histopathologic features of skull lesions can refine interpretation of DWI.

Apparent diffusion coefficient values of necrotic and solid portion of lymph nodes: differential diagnostic value in cervical lymphadenopathy

AIM

To evaluate whether the analysis of the apparent diffusion coefficient (ADC) values of the necrotic and solid portions of lymph nodes aids differentiation between the causes of cervical lymphadenopathy.

MATERIALS AND METHODS

Thirty-six patients with cervical lymph node metastasis from head and neck squamous cell carcinomas (SCC), 19 patients with lymphoma, and 23 patients with tuberculous lymphadenitis underwent conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI). The ADC values of necrotic and solid portions of lymph nodes were measured and compared. Receiver operating characteristic (ROC) analysis was employed to investigate whether ADC values could help to discriminate between the causes of cervical lymphadenopathy, and to obtain the optimal ADC threshold values.

RESULTS

The mean ADC values of the solid portions of metastatic nodes, lymphomatous nodes, and tuberculous nodes were (0.93±0.16)×10(-3)mm(2)/s, (0.64±0.13)×10(-3)mm(2)/s and (1.01±0.11)×10(-3)mm(2)/s, respectively (p<0.01). The mean ADC values of necrosis of metastatic and tuberculous nodes were (2.02±0.36)×10(-3)mm(2)/s and (1.25±0.15)×10(-3)mm(2)/s (p<0.01). By using the ADC value of the solid portion, the optimal ADC threshold values for distinguishing between metastasis and lymphoma, between metastasis and tuberculosis, and between lymphoma and tuberculosis were 0.77×10(-3), 0.98×10(-3) and 0.81×10(-3)mm(2)/s, respectively, and the sensitivities and specificities were 83 and 89%, 70 and 68%, 93 and 100%, respectively. By using ADC values of necrosis, the optimal ADC threshold value for distinguishing between metastasis and tuberculosis was 1.59×10(-3)mm(2)/s, and the sensitivity and specificity were 88 and 100%, respectively.

CONCLUSION

The ADC values both of the necrotic and solid portions of the lymph nodes are useful in differentiation between the causes of cervical lymphadenopathy. The ADC value of necrosis is especially helpful in discriminating metastasis from tuberculosis.

MR evaluation of sinonasal angiomatous polyp

BACKGROUND AND PURPOSE

SAP is a rare lesion of the sinonasal cavity, which may be misdiagnosed as a benign or malignant neoplasm. The purpose of our study was to comprehensively evaluate the MR imaging features of SAP.

MATERIALS AND METHODS

Forty patients with SAP confirmed pathologically were retrospectively reviewed. Of the 40 patients undergoing MR imaging, 39 had postcontrast T1WI; 30, DCE MR imaging; and 17, DWI. The image features assessed included the location, shape, margin, size, signal intensity, and enhancement pattern on DCE MR imaging and ADC maps.

RESULTS

All 40 SAPs originated from the maxillary sinus, but the lesions frequently extended into the ipsilateral nasal cavity (38/40), toward the choana (19/40), and into the nasopharynx (8/40). The lesions demonstrated hypointensity on T1WI and heterogenous hyperintensity on T2WI. All 40 lesions showed a peripheral hypointense rim on T2WI. Postcontrast MR imaging revealed marked heterogeneous nodular and patchy enhancement. Progressive enhancement was found on DCE MR imaging in 30 cases. The TIC showed a steady enhancement pattern in 3 cases, a rapidly enhancing and slow washout pattern in 6 cases, and a rapidly enhancing and rapid washout pattern in 21 cases. On DWI, the mean ADC value was (1.40 ± 0.20) × 10(-3) mm(2)/s.

CONCLUSIONS

Distinctive features of SAP on conventional MR imaging include internal heterogeneous hyperintensity and a peripheral hypointense rim on T2WI, as well as strong nodular and patchy enhancement on postcontrast MR images. The progressive enhancement on DCE MR imaging can also suggest the diagnosis.

Multiparametric MR imaging of sinonasal diseases: time-signal intensity curve- and apparent diffusion coefficient-based differentiation between benign and malignant lesions

BACKGROUND AND PURPOSE

The sinonasal region is a platform for a broad spectrum of benign and malignant diseases, and image-based differentiation between benign and malignant diseases in this area is often difficult. Here, we evaluated multiparametric MR imaging with combined use of TICs and ADCs for the differentiation between benign and malignant sinonasal tumors and tumorlike diseases.

MATERIALS AND METHODS

TICs obtained from dynamic contrast-enhanced MR imaging and ADCs were analyzed on a lesion-by-lesion (overall TIC and ADC) and pixel-by-pixel (TIC and ADC mapping) basis in patients with benign (n = 21) or malignant (n = 23) sinonasal tumors and tumorlike diseases. The TICs were semiautomatically classified into 5 distinctive patterns (flat, slow uptake, rapid uptake with low washout ratio, rapid uptake with high washout ratio, and miscellaneous). ADCs were determined by using b-values of 500 and 1000 s/mm(2).

RESULTS

Malignant sinonasal tumors had small (<25%) areas of the type 1 flat TIC profile as determined by pixel-by-pixel TIC analysis and large (≥50%) areas of low or extremely low ADCs (≤1.2 × 10(-3) mm(2/)s) as determined by ADC mapping. Consequently, stepwise classification on the basis of TICs and ADCs successfully (at 100% accuracy) discriminated malignant from benign sinonasal diseases in the present patient cohort.

CONCLUSIONS

Multiparametric MR imaging by using TICs and ADCs may help differentiate benign and malignant sinonasal diseases.

Functional imaging in head and neck squamous cell carcinoma: correlation of PET/CT and diffusion-weighted imaging at 3 Tesla

PURPOSE

The purposes of this study were: (a) to prospectively assess the correlation between apparent diffusion coefficient (ADC) values and maximum standardized uptake values (SUVmax) in patients with head and neck squamous cell carcinomas (SCC); and (b) to assess ADC and SUVmax values in relation to different tumour grades and stages in our patient population.

METHODS

The study group comprised 31 consecutive patients with biopsy-proven head and neck squamous cell carcinoma who were examined using a 3T MRI scanner with a 16-channel head and neck coil. In addition to routine sequences, axial (DWIBS) and sagittal (DW-EPI) diffusion-weighted sequences were obtained using b-values of 0 mm(2)/s and 800 mm(2)/s. The ADC maps were calculated automatically. The ADC values of the tumours were measured with three regions of interest (ROIs) of standard size, and an ROI covering the entire tumour. In all patients, contrast-enhanced, whole-body (18)F-FDG PET/CT was performed within 2 weeks of the MRI examination. SUVmax was measured for every tumour using a 3-D freehand ROI that covered the entire tumour. Two-way repeated measures ANOVA was used for group comparisons. The Spearman rank correlation test was performed for ADC values.

RESULTS

Mean ADC values in the 31 SCC were 0.902 (± 0.134) with a ROI of standard size, and 0.928 (± 0.160) with the large ROI measurements on the axial DWIBS sequence. The ADC values of the tumours were significantly higher when measured with the sagittal DW-EPI sequence: 1.051 (± 0.211) and 1.082 (± 0.208). We observed no significant differences in ADC values and SUVmax between the various T stages or histological grades of the tumours. SUVmax values (26.5 ± 12) did not correlate with ADC values on DWIBS or EPI.

CONCLUSION

There is no correlation between the FDG uptake and the ADC value in head and neck SCC. The three different tumour grades and four tumour stages present in our study population could not be differentiated based on ADC values or SUV.

[Radiological diagnosis of the paranasal sinuses]

Although diseases of the paranasal sinuses have a relatively homogeneous clinical presentation, their causes can vary considerably. Radiological imaging only became relevant in paranasal sinus diagnostics following the introduction of cross-sectional imaging. In addition to technical details on imaging procedures and the individual criteria of the different modalities, anatomic details and congenital variations are presented. Particularly in acute inflammatory diseases as well as traumatic lesions, imaging is essential in preoperative planning and postoperative control. The article gives a detailed description of options in radiologic imaging of the paranasal sinuses.