Risk Severity Model for Pediatric Autosomal Dominant Polycystic Kidney Disease Using 3D Ultrasound Volumetry

BACKGROUND

Height-adjusted total kidney volume (htTKV) measured by imaging defined as Mayo Imaging Class (MIC) is a validated prognostic measure for autosomal dominant polycystic kidney disease (ADPKD) in adults to predict and stratify disease progression. However, no stratification tool is currently available in pediatric ADPKD. Because magnetic resonance imaging and computed tomography in children are difficult, we propose a novel 3D ultrasound-based pediatric Leuven Imaging Classification to complement the MIC.

METHODS

A prospective study cohort of 74 patients with genotyped ADPKD (37 female) was followed longitudinally with ultrasound, including 3D ultrasound, and they underwent in total 247 3D ultrasound assessments, with patients' median age (interquartile range [IQR]) at diagnosis of 3 (IQR, 0-9) years and at first 3D ultrasound evaluation of 10 (5-14) years. First, data matching was done to the published MIC classification, followed by subsequent optimization of parameters and model type.

RESULTS

PKD1 was confirmed in 70 patients (95%), PKD2 in three (4%), and glucosidase IIα unit only once (1%). Over these 247 evaluations, the median height was 143 (IQR, 122-166) cm and total kidney volume was 236 (IQR, 144-344) ml, leading to an htTKV of 161 (IQR, 117-208) ml/m. Applying the adult Mayo classification in children younger than 15 years strongly underestimated ADPKD severity, even with correction for height. We therefore optimized the model with our pediatric data and eventually validated it with data of young patients from Mayo Clinic and the Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease used to establish the MIC.

CONCLUSIONS

We proposed a five-level Leuven Imaging Classification ADPKD pediatric model as a novel classification tool on the basis of patients' age and 3D ultrasound-htTKV for reliable discrimination of childhood ADPKD severity.

Development and characterization of a rat brain metastatic tumor model by multiparametric magnetic resonance imaging and histomorphology

To facilitate the development of new brain metastasis (BM) treatment, an easy-to-use and clinically relevant animal model with imaging platform is needed. Rhabdomyosarcoma BM was induced in WAG/Rij rats. Post-implantation surveillance and characterizations were systematically performed with multiparametric MRI including 3D T1 and T2 weighted imaging, diffusion-weighted imaging (DWI), T1 and T2 mapping, and perfusion-weighted imaging (PWI), which were validated by postmortem digital radiography (DR), µCT angiography and histopathology. The translational potential was exemplified by the application of a vascular disrupting agent (VDA). BM was successfully induced in most rats of both genders (18/20). Multiparametric MRI revealed significantly higher T2 value, pre-contrast-enhanced (preCE) T1 value, DWI-derived apparent diffusion coefficient (ADC) and CE ratio, but a lower post-contrast-enhanced (postCE) T1 value in BM lesions than in adjacent brain (p < 0.01). PWI showed the dynamic and higher contrast agent uptake in the BM compared with the adjacent brain. DR, µCT and histopathology characterized the BM as hypervascular tumors. After VDA treatment, the BM showed drug-related perfusion changes and partial necrosis as evidenced by anatomical, functional MRI parameters and postmortem findings. The present BM model and imaging modalities represent a feasible and translational platform for developing BM-targeting therapeutics.

Early Whole-Body Diffusion-weighted MRI Helps Predict Long-term Outcome Following Peptide Receptor Radionuclide Therapy for Metastatic Neuroendocrine Tumors

Purpose To evaluate the predictive value of 7-week apparent diffusion coefficient change from baseline (ADCratio_7w) at whole-body diffusion-weighted MRI (WB-DWI MRI) after one peptide receptor radionuclide therapy (PRRT) cycle to predict outcome in patients with metastatic neuroendocrine tumor (mNET). Materials and Methods From April 2009 to May 2012, participants in a prospective clinical trial investigating yttrium 90-DOTA Phe1-Tyr³-octreotide (DOTATOC) treatment for mNET (EudraCT no. 2008-007965-22) underwent WB-DWI MRI and gallium 68 (⁶⁸Ga)-DOTATOC PET/CT before and 7 weeks after one PRRT cycle. ADCratio_7w response was compared with the 7-week Response Evaluation Criteria in Solid Tumors version 1.1 and ⁶⁸Ga-DOTATOC PET/CT quantitative responses to predict overall survival (OS) and progression-free survival (PFS) with Cox regression analysis. Results Forty participants were analyzed (mean age, 60 years ± 11 [SD]; 21 men). Median PFS and OS were 10.5 months (range, 2-36 months) and 18 months (range, 3-81 months), respectively. Survival analysis showed significantly positive effects on PFS by age (hazard ratio [HR] = 0.96, P = .007), tumor grade (HR = 2.84, P = .006), Ki-67 index (HR = 1.05, P = .01), ADCratio_7w of the least-responding lesion (ADCratio_7w-least) (HR = 0.94, P < .001), and baseline mean standardized uptake values (SUV_mean) (HR = 0.89, P = .02), with ADCratio_7w-least and SUV_mean remaining significant in multivariable analysis (P < .001, P = .02, respectively). There were significantly positive effects on OS by pretreatment lesion volume (HR = 1.004, P = .004), tumor grade (HR = 2.14, P = .04), Ki-67 index (HR = 1.05, P = .01), and ADCratio_7w-least (HR = 0.97, P < .001), with pretreatment volume and ADCratio_7w-least remaining significant at multivariable analysis (P = .005, P = .002, respectively). Conclusion The ADCratio_7w after start of PRRT for mNET was an independent predictor of patient outcome. Keywords: MR-Diffusion-Weighted Imaging, Radionuclide Therapy, Whole-Body Imaging, Metastases, Tumor Response, Treatment Effects EudraCT no. 2008-007965-22 © RSNA, 2022.

Morphometric evaluation of traumatic axonal injury and the correlation with post-traumatic cerebral atrophy and functional outcome

INTRODUCTION

Imaging plays a crucial role in the diagnosis, prognosis and follow-up of traumatic brain injury. Whereas computed tomography plays a pivotal role in the acute setting, magnetic resonance imaging is best suited to detect the true extent of traumatic brain injury, and more specifically diffuse axonal injury. Post-traumatic brain atrophy is a well-known complication of traumatic brain injury.

PURPOSE

This study investigated the correlation between diffuse axonal injury detected with fluid-attenuated inversion recovery and susceptibility-weighted imaging magnetic resonance imaging, post-traumatic brain atrophy and functional outcome (Glasgow outcome scale - extended).

MATERIALS AND METHODS

Twenty patients with a closed head injury and diffuse axonal injury detected with fluid-attenuated inversion recovery and susceptibility-weighted imaging were included. The total volumes of the diffuse axonal injury fluid-attenuated inversion recovery lesions were determined for each subject's initial (<14 days) and follow-up magnetic resonance scan (average: day 303 ± 83 standard deviation). The different brain volumes were automatically quantified using a validated and both US Food and Drug Administration-cleared and CE-marked machine learning algorithm (icobrain). The number of susceptibility-weighted imaging lesions and functional outcome scores (Glasgow outcome scale - extended) were retrieved from the Collaborative European NeuroTrauma Effectiveness Research Traumatic Brain Injury dataset.

RESULTS

The volumetric fluid-attenuated inversion recovery diffuse axonal injury lesion load showed a significant inverse correlation with functional outcome (Glasgow outcome scale - extended) (r = -0.57; P = 0.0094) and white matter volume change (r = -0.50; P = 0.027). In addition, white matter volume change correlated significantly with the Glasgow outcome scale - extended score (P = 0.0072; r = 0.58). Moreover, there was a strong inverse correlation between longitudinal fluid-attenuated inversion recovery lesion volume change and whole brain volume change (r = -0.63; P = 0.0028). No significant correlation existed between the number of diffuse axonal injury susceptibility-weighted imaging lesions, brain atrophy and functional outcome.

CONCLUSIONS

Volumetric analysis of diffuse axonal injury on fluid-attenuated inversion recovery imaging and automated brain atrophy calculation are potentially useful tools in the clinical management and follow-up of traumatic brain injury patients with diffuse axonal injury.

Quantitative Whole-Body Diffusion-weighted MRI after One Treatment Cycle for Aggressive Non-Hodgkin Lymphoma Is an Independent Prognostic Factor of Outcome

Purpose

To evaluate the prognostic utility of apparent diffusion coefficient (ADC) changes at whole-body diffusion-weighted (WB-DW) MRI after one treatment cycle for aggressive non-Hodgkin lymphoma (NHL) compared with response assessment at interim and end-of-treatment fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET/CT.

Materials and Methods

This was a secondary analysis of a prospective study (ClinicalTrials.gov identifier: NCT01231269) in which participants with aggressive NHL were recruited between March 2011 and April 2015 and underwent WB-DW MRI before and after one cycle of immunochemotherapy. Volunteers were recruited for test-retest WB-DW MRI (ClinicalTrials.gov identifier: NCT01231282) to assess ADC measurement repeatability. Response assessment was based on ADC change after one treatment cycle at WB-DW MRI and Deauville criteria at ¹⁸F-FDG PET/CT. To evaluate prognostic factors of disease-free survival (DFS), Kaplan-Meier survival analysis and univariable and multivariable Cox regression were performed; intraclass correlation coefficient (ICC) and mean difference with limits of agreement were calculated to determine inter- and intraobserver repeatability of ADC measurements.

Results

Forty-five patients (mean age, 58 years ± 17 [standard deviation]; 31 men) and nine volunteers (mean age, 22 years ± 3; seven men) were enrolled. Median DFS was 48 months (range, 2-48 months). Outcome prediction accuracy was 86.7% (39 of 45), 71.4% (30 of 42), and 73.8% (31 of 42) for WB-DW MRI and interim and end-of-treatment ¹⁸F-FDG PET/CT, respectively. WB-DW MRI (hazard ratio [HR], 17.8; P < .001) and interim (HR, 5; P = .008) and end-of-treatment (HR, 4.3; P = .017) ¹⁸F-FDG PET/CT were prognostic of DFS. After multivariable analysis, WB-DW MRI remained an independent predictor of outcome (HR, 26.8; P = .002). Intra- and interobserver agreement for ADC measurements were excellent (ICC = 0.85-0.99).

Conclusion

Quantitative WB-DW MRI after only one cycle of immunochemotherapy predicts DFS in aggressive NHL and is noninferior to routinely performed interim and end-of-treatment ¹⁸F-FDG PET/CT.Keywords: MR-Diffusion Weighted Imaging, Lymphoma, Oncology, Tumor Response, Whole-Body ImagingSupplemental material is available for this article.© RSNA, 2021.

Accuracy of whole-body diffusion-weighted MRI (WB-DWI/MRI) in diagnosis, staging and follow-up of gastric cancer, in comparison to CT: a pilot study

Background

Accurate staging of patients with gastric cancer is necessary for selection of the most appropriate and personalized therapy. Computed tomography (CT) is currently used as primary staging tool, being widely available with a relatively high accuracy for the detection of parenchymal metastases, but with low sensitivity for the detection of peritoneal metastases. Magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) has a very high contrast resolution, suggesting a higher diagnostic performance in the detection of small peritoneal lesions. The aim of this study was to retrospectively evaluate the added value of whole-body diffusion-weighted MRI (WB-DWI/MRI) to CT for detection of peritoneal carcinomatosis (PC) and distant metastases in the preoperative staging of gastric cancer.

Methods

This retrospective study included thirty-two patients with a suspicion of gastric cancer/recurrence, who underwent WB-DWI/MRI at 1.5 T, in addition to CT of thorax and abdomen. Images were evaluated by two experienced abdominal radiologists in consensus. Histopathology, laparoscopy and/or 1-year follow-up were used as reference standard.

Results

For overall tumour detection (n = 32), CT sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was 83.3%, 100%, 100% and 82.4% respectively. For WB-DWI/MRI these values were 100%, 92.9%, 94.7% and 100%, respectively. For staging (n = 18) malignant lymph nodes and metastases, CT had a sensitivity, specificity/PPV/NPV of 50%/100%/100%/71.4%, and 15.4%/100%/100%/31.3% respectively. For WB-DWI/MRI, all values were 100%, for both malignant lymph nodes and metastases. WB-DWI/MRI was significantly better than CT in detecting tumour infiltration of the mesenteric root, serosal involvement of the small bowel and peritoneal metastases for which WB-DWI/MRI was correct in 100% of these cases, CT 0%.

Conclusions

WB-DWI/MRI is highly accurate for diagnosis, staging and follow-up of patients with suspected gastric cancer.

Whole-body diffusion-weighted magnetic resonance imaging for the detection of bone metastases and their prognostic impact in metastatic renal cell carcinoma patients treated with angiogenesis inhibitors

Background: Metastatic renal cell carcinoma (mRCC) patients with bone metastases (BM) are at high risk for skeletal related events and have a poorer outcome when treated with vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs). Computed tomography (CT) lacks sensitivity to detect BM in mRCC. We aimed to determine the added value of whole body diffusion-weighted magnetic resonance imaging (WB-DWI/MRI) to CT for the detection of BM in mRCC and to estimate the prognostic impact of the number of BM in mRCC patients treated with VEGFR-TKIs.Material and methods: We conducted a prospective study including consecutive mRCC patients treated with a first-line VEGFR-TKI in the metastatic setting. All patients underwent a pretreatment thoracic-abdominal-pelvic CT and WB-DWI/MRI. CT and WB-DWI/MRI were compared for the detection of BM. The number of detected BM was correlated with response rate (RR), progression-free survival (PFS) and overall survival (OS) after start of the VEGFR-TKI.Results: Ninety-two patients were included. BM were found in 55% of the patients by WB-DWI/MRI and in 43% of the patients by CT (p = .003). Mean number of BM discovered per patient was 6.8 by WB-DWI/MRI versus 1.9 by CT (p = .006). The cutoff of ≤5 versus >5 BM on WB-DWI/MRI had the highest discriminative power for all outcome measures. Patients with >5 BM had a lower RR (10% versus 42%), more frequently early progressive disease (43% versus 13%, p = .003), shorter PFS (4 versus 10 months, p = .006) and shorter OS (10 versus 35 months, p < .0001) compared to patients with ≤5 BM.Conclusion: WB-DWI/MRI detects significantly more BM in mRCC patients than CT, allowing better estimation of the prognostic impact of BM in mRCC patients treated with VEGFR-TKIs. The prognostic impact should now be validated in patients treated with immune checkpoint inhibitors.

Predicting Therapeutic Efficacy of Vascular Disrupting Agent CA4P in Rats with Liver Tumors by Hepatobiliary Contrast Agent Mn-DPDP-Enhanced MRI

To evaluate hepatobiliary-specific contrast agent (CA) mangafodipir trisodium (Mn-DPDP)–enhanced magnetic resonance imaging (MRI) for predicting the therapeutic efficacy of the vascular disrupting agent combretastatin A4 phosphate (CA4P) in rats with primary and secondary liver tumors, 36 primary hepatocellular carcinomas (HCCs) were raised by diethylnitrosamine gavage in 16 male rats, in 6 of which one rhabdomyosarcomas (R1) was intrahepatically implanted as secondary liver tumors. On a 3.0T MR scanner with a wrist coil, tumors were monitored weekly by T2-/T1-weighted images (T2WI/T1WI) and characterized by Mn-DPDP-enhanced MRI. CA4P-induced intratumoral necrosis was depicted by nonspecific gadoterate meglumine (Gd-DOTA)–enhanced MRI before and 12 h after therapy. Changes of tumor-to-liver contrast (ΔT/L) on Mn-DPDP-enhanced images were analyzed. In vivo MRI findings were verified by postmortem microangiography and histopathology. Rat models of primary HCCs in a full spectrum of differentiation and secondary R1 liver tumors were successfully generated. Mn-DPDP-enhanced ΔT/L was negatively correlated with HCC differentiation grade (P < 0.01). After treatment with CA4P, more extensive tumoral necrosis was found in highly differentiated HCCs than that in moderately and poorly differentiated ones (P < 0.01); nearly complete necrosis was induced in secondary liver tumors. Mn-DPDP-enhanced MRI may help in imaging diagnosis of primary and secondary liver malignancies of different cellular differentiations and further in predicting CA4P therapeutic efficacy in primary HCCs and intrahepatic metastases.

Whole-body diffusion-weighted MRI for operability assessment in patients with colorectal cancer and peritoneal metastases

Background

Correct staging of patients with colorectal cancer is of utmost importance for the prediction of operability. Although computed tomography (CT) has a good overall performance, estimation of peritoneal cancer spread is a known weakness, a problem that cannot always be overcome by Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT); especially in infiltrative and miliary disease spread. Due to its high spatial and contrast resolution magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) might have a better performance. Our aim was to evaluate the added value of whole-body diffusion-weighted MRI (WB-DWI/MRI) to CT for prediction of peritoneal cancer spread and operability assessment in colorectal cancer patients with clinically suspected peritoneal carcinomatosis (PC).

Methods

This institutional review board approved retrospective study included sixty colorectal cancer patients who underwent WB-DWI/MRI in addition to CT for clinically suspected peritoneal metastases. WB-DWI/MRI and CT were assessed for detecting PC following the peritoneal cancer index (PCI), determination of PCI-score categorized as PC < 12, PCI = 12–15 and PCI > 15, detection of nodal and distant metastases and estimation of overall operability. Histopathology after surgery and biopsy and/or 6 months follow-up were used as reference standard.

Results

For detection of PC, CT had 43.2% sensitivity, 95.6% specificity, 84.5% positive predictive value (PPV) and 75.2% negative predictive value (NPV). WB-DWI/MRI had 97.8% sensitivity, 93.2% specificity, 88.9% PPV and 98.7% NPV. WB-DWI/MRI enabled better detection of inoperable distant metastases (all 12 patients) than CT (2/12 patients) and significantly improved prediction of PCI category [WB-DWI/MRI PCI < 12: 37/39 patients (94.9%); PCI = 12–15: 4/4 patients (100%); PCI > 15: 16/17 patients (94.1%) versus CT PCI < 12: 38/39 patients (97.4%); PCI = 12–15: 0/4 patients (0%); PCI > 15: 2/17 patients (11.8%); p < 0.0001)]. WB-DWI/MRI improved prediction of inoperability over CT with 90.6% sensitivity compared to 25% (p < 0.0001).

Conclusions

WB-DWI/MRI significantly outperformed CT for estimation of spread of PC, overall staging and prediction of operability. Pending validation in larger prospective trials, WB-DWI/MRI could be used to guide surgical planning and minimize unnecessary exploratory laparotomies.

Intra-individual comparison of therapeutic responses to vascular disrupting agent CA4P between rodent primary and secondary liver cancers

AIM

To compare therapeutic responses of a vascular-disrupting-agent, combretastatin-A4-phosphate (CA4P), among hepatocellular carcinomas (HCCs) and implanted rhabdomyosarcoma (R1) in the same rats by magnetic-resonance-imaging (MRI), microangiography and histopathology.

METHODS

Thirty-six HCCs were created by diethylnitrosamine gavage in 14 rats that were also intrahepatically implanted with one R1 per rat as monitored by T2-/T1-weighted images (T2WI/T1WI) on a 3.0T clinical MRI-scanner. Vascular response and tumoral necrosis were detected by dynamic contrast-enhanced (DCE-) and CE-MRI before, 1 h after and 12 h after CA4P iv at 10 mg/kg (treatment group n = 7) or phosphate-buffered saline at 1.0 mL/kg (control group n = 7). Tumor blood supply was calculated by a semiquantitative DCE parameter of area under the time signal intensity curve (AUC30). In vivo MRI findings were verified by postmortem techniques.

RESULTS

On CE-T1WIs, unlike the negative response in all tumors of control animals, in treatment group CA4P caused rapid extensive vascular shutdown in all R1-tumors, but mildly or spottily in HCCs at 1 h. Consequently, tumor necrosis occurred massively in R1-tumors but patchily in HCCs at 12 h. AUC30 revealed vascular closure (66%) in R1-tumors at 1 h (P < 0.05), followed by further perfusion decrease at 12 h (P < 0.01), while less significant vascular clogging occurred in HCCs. Histomorphologically, CA4P induced more extensive necrosis in R1-tumors (92.6%) than in HCCs (50.2%) (P < 0.01); tumor vascularity heterogeneously scored +~+++ in HCCs but homogeneously scored ++ in R1-tumors.

CONCLUSION

This study suggests superior performance of CA4P in metastatic over primary liver cancers, which could guide future clinical applications of vascular-disrupting-agents.​

The first study on therapeutic efficacies of a vascular disrupting agent CA4P among primary hepatocellular carcinomas with a full spectrum of differentiation and vascularity: Correlation of MRI-microangiography-histopathology in rats

To better inform the next clinical trials of vascular disrupting agent combretastatin-A4-phosphate (CA4P) in patients with hepatic malignancies, this preclinical study aimed at evaluating CA4P therapeutic efficacy in rats with primary hepatocellular carcinomas (HCCs) of a full spectrum of differentiation and vascularity by magnetic resonance imaging (MRI), microangiography and histopathology. Ninety-six HCCs were raised in 25 rats by diethylnitrosamine gavage. Tumor growth was monitored by T2-/T1-weighted-MRI (T2WI, T1WI) using a 3.0 T scanner. Early vascular response and later intratumoral necrosis were detected by dynamic-contrast-enhanced (DCE) MRI and diffusion-weighted-imaging (DWI) before, 1 and 12 hr after CA4P iv-administration. In vivo MRI-findings were validated by postmortem-techniques. Multi-parametric MRI revealed rapid CA4P-induced tumor vascular shutdown within 1 hr, followed by variable intratumoral necrosis at 12 hr. Tumor volumes decreased by 10% at 1 hr (p < 0.05), but resumed at 12 hr. Correlations of semi-quantitative DCE parameter initial-area-under-the-gadolinium-curve (IAUGC30) with histopathology proved partial vascular closure and compensational reopening (p < 0.05). The higher grades of vascularity prevented those residual tumor tissues from CA4P-caused ischemic necrosis. By histopathology using a 4-scale cellular-differentiation criteria and a 4-grade tumor-vascularity classification, percentage of CA4P-induced necrosis negatively correlated with HCC differentiation (r = -0.404, p < 0.001) and tumor vascularity (r = -0.370, p < 0.001). Ordinal-logistic-regression helped to predict early tumor responses to CA4P in terms of tumoral differentiation and vascularity. Our study demonstrated that CA4P could induce vascular shutdown in primary HCCs within 1 hr, resulting in various degrees of tumor necrosis at 12 hr. MRI as a real-time imaging biomarker may help to define tumor vascularity and differentiation and further to predict CA4P therapeutic outcomes.

Feasibility of whole-body diffusion-weighted MRI for detection of primary tumour, nodal and distant metastases in women with cancer during pregnancy: a pilot study

OBJECTIVES

To evaluate the feasibility of whole-body diffusion-weighted MRI (WB-DWI/MRI) for detecting primary tumour, nodal and distant metastases in pregnant women with cancer.

METHODS

Twenty pregnant patients underwent WB-DWI/MRI in additional to conventional imaging. Reproducibility of WB-DWI/MRI between two readers was evaluated using Cohen's κ statistics and accuracy was compared to conventional imaging for assessing primary tumour site, nodal and visceral metastases.

RESULTS

Both WB-DWI/MRI readers showed good-very good agreement for lesion detection (primary lesions: κ=1; lymph nodes: κ=0.89; distant metastases: κ=0.61). Eight (40 %) patients were upstaged after WB-DWI/MRI. For nodal metastases, WB-DWI/MRI showed 100 % (95 % CI: 83.2-100) sensitivity for both readers with specificity of 99.4 % (96.9-100) and 100 % (80.5-100) for readers 1 and 2, respectively. For distant metastases, WB-DWI/MRI showed 66.7 % (9.4-99.2) and 100 % (29.2-100) sensitivity and specificity of 94.1 % (71.3-99.9) and 100 % (80.5-100) for readers 1 and 2, respectively. Conventional imaging showed sensitivity of 50 % (27.2-72.8) and 33.3 % (0.8-90.6); specificity of 100 % (98-100) and 100 % (80.5-100), for nodal and distant metastases respectively.

CONCLUSIONS

WB-DWI/MRI is feasible for single-step non-invasive staging of cancer during pregnancy with additional value for conventional imaging procedures.

KEY POINTS

• In our study, WB-DWI/MRI was more accurate than conventional imaging during pregnancy. • WB-DWI/MRI improves diagnostic assessment of patients with cancer during pregnancy. • Accurate imaging and oncologic staging improves treatment and outcome.

Micro-HCCs in rats with liver cirrhosis: paradoxical targeting effects with vascular disrupting agent CA4P

We sought to investigate anticancer efficacy of a vascular disrupting agent (VDA) combretastatin A-4 phosphate (CA4P) in relation to tumor size among hepatocellular carcinomas (HCCs) in rats using magnetic resonance imaging (MRI) and postmortem techniques. Nineteen rats with 43 chemically-induced HCCs of 2.8–20.9 mm in size on liver cirrhosis received CA4P intravenously at 10 mg/kg. Tumor-diameter was measured by T2-weighted imaging (T2WI) to define microcancers (< 5 mm) versus larger HCCs. Vascular responses and tissue necrosis were detected by diffusion-weighted imaging (DWI), contrast-enhanced T1-weighted imaging (CE-T1WI) and dynamic contrast enhanced (DCE-) MRI, which were validated by microangiography and histopathology. MRI revealed nearly complete necrosis in 5 out of 7 micro-HCCs, but diverse therapeutic necrosis in larger HCCs with a positive correlation with tumor size. Necrosis in micro-HCCs was 36.9% more than that in larger HCCs. While increased diffusion coefficient (ADC_diff) suggested tumor necrosis, perfusion coefficient (ADC_perf) indicated sharply decreased blood perfusion in cirrhotic liver together with a reduction in micro-HCCs. DCE revealed lowered tumor blood flow from intravascular into extravascular extracellular space (EES). Microangiography and histopathology revealed hypo- and hypervascularity in 4 and 3 micro-HCCs, massive, partial and minor degrees of tumoral necrosis in 5, 1 and 1 micro-HCCs respectively, and patchy necrotic foci in cirrhotic liver. CD34-PAS staining implicated that poorly vascularized micro-HCCs growing on liver cirrhosis tended to respond better to CA4P treatment. In this study, more complete CA4P-response occurred unexpectedly in micro-HCCs in rats, along with CA4P-induced necrotic foci in cirrhotic liver. These may help to plan clinical applications of VDAs in patients with HCCs and liver cirrhosis.

Whole body diffusion-weighted MRI to predict treatment outcome after one cycle of immunochemotherapy in aggressive non-Hodgkin lymphoma

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Background: Treatment adaptation based on early identification of non-Hodgkin lymphoma (NHL) patients not responding to therapy might improve survival. The role of interim fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) after 2-4 cycles of immunochemotherapy (ICT) herein is experimental as it renders false positive results, due to a rituximab-induced inflammatory response. Whole body diffusion-weighted magnetic resonance imaging (WB-DWI/MRI) was evaluated as a radiation-free imaging technique to predict treatment outcome in NHL after one cycle ICT (2-3 weeks). Methods: 47 patients with aggressive NHL (35 DLBCL,2 primary mediastinal BCL,3 unclassifiable BCL, 2 Burkitt,2 MCL, 2 peripheral TCL and 1 extranodal NK-TCL) were enrolled. All had baseline and interim WB-DWI/MRI, and end-of-treatment PET/CT; 39/47 had interim PET/CT. International prognostic index (IPI), immunohistochemical (IHC) markers Ki-67, Bcl-6 and Bcl-2 were evaluated for their predictive value. WB-DWI/MRI was assessed quantitatively with histogram analysis (high b-value signal intensity (SI) and apparent diffusion coefficient (ADC)). Patients were categorized as non-responder when lesions had decreased ADC or insufficient SI decrease between scans. Kaplan-Meier survival analysis was performed with log rank, Cox hazard ratio calculation and multivariate analysis. Outcome measure was disease-free-survival (DFS). Results: Median follow-up time was 43 months (4-70 months). 33 patients had complete remission (CR), 5 progression and 9 recurrent disease. WB-DWI/MRI predicted DFS correctly in 45/47 (96%) [log rank p<0.001; hazard ratio (HR) 52, (CI 95% 6-401)]; end-of-treatment PET/CT was correct in 37/47 (79%) [p=0.003;HR 4.3, (1.5-12.4)], and interim PET/CT in 28/39 (72%) [p=0.016;HR 3.9, (1.2-12.5)]. IPI score and IHC parameters were not significantly predictive. Multivariate analysis showed WB-DWI/MRI as the only independent prognostic factor (p<0.001). Conclusions: WB-DWI/MRI can accurately predict treatment outcome in aggressive NHL after only one cycle of immunochemotherapy without the burden of radiation exposure. Clinical trial information: NCT01231269.

Rationale for Modernising Imaging in Advanced Prostate Cancer

CONTEXT

To effectively manage patients with advanced prostate cancer (APC), it is essential to have accurate, reproducible, and validated methods for detecting and quantifying the burden of bone and soft tissue metastases and for assessing their response to therapy. Current standard of care imaging with bone and computed tomography (CT) scans have significant limitations for the assessment of bone metastases in particular.

OBJECTIVE

We aimed to undertake a critical comparative review of imaging methods used for diagnosis and disease monitoring of metastatic APC from the perspective of their availability and ability to assess disease presence, extent, and response of bone and soft tissue disease.

EVIDENCE ACQUISITION

An expert panel of radiologists, nuclear medicine physicians, and medical physicists with the greatest experience of imaging in advanced prostate cancer prepared a review of the practicalities, performance, merits, and limitations of currently available imaging methods.

EVIDENCE SYNTHESIS

Meta-analyses showed that positron emission tomography (PET)/CT with different radiotracers and whole-body magnetic resonance imaging (WB-MRI) are more accurate for bone lesion detection than CT and bone scans (BSs). At a patient level, the pooled sensitivities for bone disease by using choline (CH)-PET/CT, WB-MRI, and BS were 91% (95% confidence interval [CI], 83-96%), 97% (95% CI, 91-99%), and 79% (95% CI, 73-83%), respectively. The pooled specificities for bone metastases detection using CH-PET/CT, WB-MRI, and BS were 99% (95% CI, 93-100%), 95% (95% CI, 90-97%), and 82% (95% CI, 78-85%), respectively. The ability of PET/CT and WB-MRI to assess therapeutic benefits is promising but has not been comprehensively evaluated. There is variability in the cost, availability, and quality of PET/CT and WB-MRI.

CONCLUSIONS

Standardisation of acquisition, interpretation, and reporting of WB-MRI and PET/CT scans is required to assess the performance of these techniques in clinical trials of treatment approaches in APC.

PATIENT SUMMARY

PET/CT and whole-body MRI scans have the potential to improve detection and to assess response to treatment of all states of advanced prostate cancer. Consensus recommendations on quality standards, interpretation, and reporting are needed but will require validation in clinical trials of established and new treatment approaches.

METastasis Reporting and Data System for Prostate Cancer: Practical Guidelines for Acquisition, Interpretation, and Reporting of Whole-body Magnetic Resonance Imaging-based Evaluations of Multiorgan Involvement in Advanced Prostate Cancer

CONTEXT

Comparative reviews of whole-body magnetic resonance imaging (WB-MRI) and positron emission tomography/computed tomography (CT; with different radiotracers) have shown that metastasis detection in advanced cancers is more accurate than with currently used CT and bone scans. However, the ability of WB-MRI and positron emission tomography/CT to assess therapeutic benefits has not been comprehensively evaluated. There is also considerable variability in the availability and quality of WB-MRI, which is an impediment to clinical development. Expert recommendations for standardising WB-MRI scans are needed, in order to assess its performance in advanced prostate cancer (APC) clinical trials.

OBJECTIVE

To design recommendations that promote standardisation and diminish variations in the acquisition, interpretation, and reporting of WB-MRI scans for use in APC.

EVIDENCE ACQUISITION

An international expert panel of oncologic imagers and oncologists with clinical and research interests in APC management assessed biomarker requirements for clinical care and clinical trials. Key requirements for a workable WB-MRI protocol, achievable quality standards, and interpretation criteria were identified and synthesised in a white paper.

EVIDENCE SYNTHESIS

The METastasis Reporting and Data System for Prostate Cancer guidelines were formulated for use in all oncologic manifestations of APC.

CONCLUSIONS

Uniformity in imaging data acquisition, quality, and interpretation of WB-MRI are essential for assessing the test performance of WB-MRI. The METastasis Reporting and Data System for Prostate Cancer standard requires validation in clinical trials of treatment approaches in APC.

PATIENT SUMMARY

METastasis Reporting and Data System for Prostate Cancer represents the consensus recommendations on the performance, quality standards, and reporting of whole-body magnetic resonance imaging, for use in all oncologic manifestations of advanced prostate cancer. These new criteria require validation in clinical trials of established and new treatment approaches in advanced prostate cancer.

Whole-body diffusion-weighted magnetic resonance imaging in the diagnosis of recurrent ovarian cancer: a clinical feasibility study

OBJECTIVE

To assess the clinical feasibility of whole-body diffusion-weighted MRI (WB-DWI/MRI) for diagnosis and prediction of complete tumour resection in patients with suspected recurrent ovarian cancer.

METHODS

51 females clinically suspected for ovarian cancer recurrence underwent 3-T WB-DWI/MRI in addition to contrast-enhanced CT. WB-DWI/MRI was assessed for detection of tumour recurrence, prediction of tumour extent and complete resection compared with CT. Tumour presence was confirmed by pathology obtained by surgery or biopsy, or by imaging follow-up.

RESULTS

WB-DWI/MRI showed 94% accuracy for detecting ovarian cancer recurrence, compared with 78% for CT (p = 0.008). WB-DWI/MRI showed better sensitivity [% (95% confidence interval)] than CT for detecting involvement of surgically critical tumour sites including mesenteric root infiltration [92 (62-100) vs 31 (10-61)], small bowel [93 (64-100) vs 21 (6-51)], colon carcinomatosis [91 (57-100) vs 27 (7-61)] and unresectable distant metastases [90 (54-99) vs 20 (4-56)]. WB-DWI/MRI correctly predicted complete resection in 33 of 35 (94%) patients eligible for salvage surgery compared with 17 of 35 (49%) for CT (p < 0.001).

CONCLUSION

WB-DWI/MRI allowed better detection of ovarian cancer recurrence and better prediction of complete resection than CT. Advances in knowledge: WB-DWI/MRI could assist in optimizing treatment planning for recurrent ovarian cancer, particularly by improving patient selection for salvage surgery, thus giving eligible patients the highest chance on prolonged survival and refraining patients who would not benefit from extensive surgery reducing related morbidity and mortality.

Staging of prostatic carcinoma at 1.5-T MRI: correlation of a simplified MRI exam with whole-mount radical prostatectomy specimens

OBJECTIVE

To retrospectively analyze the accuracy of simplified multiparametric MRI at 1.5 T for local staging by using whole-mount-section histopathological analysis as the standard of reference.

METHODS

123 consecutive patients underwent T2 weighted, T1 weighted and diffusion-weighted MRI without endorectal coil prior to radical prostatectomy. The accuracy of predicting extracapsular extension (ECE) (T3a) was assessed using direct signs or the combination of direct and indirect signs of extraprostatic extension. The accuracy of predicting seminal vesicle invasion (T3b) was evaluated, taking into account different routes of seminal vesicle involvement. Finally, adjacent organ invasion (T4) was evaluated in this patient population.

RESULTS

Histopathology showed T3a, T3b and T4 in 61, 28 and 9 cases, respectively. The use of direct signs of extraprostatic extension showed a sensitivity of 57.4% and specificity of 91.9%. The combination of direct signs and indirect signs improved sensitivity (85.2%) at the expense of moderate loss of specificity (83.9%). MR sensitivity for the detection of seminal vesicle invasion was low (53.6%); however, it was dependent on the route of seminal vesicle tumour infiltration. MR sensitivity and specificity for adjacent organ invasion were 88.9% and 99.1%.

CONCLUSION

Simplified MRI study at 1.5 T provides a relatively high sensitivity for detecting ECE (T3a) when using the combination of indirect and direct signs. However, this high sensitivity reading is at the cost of a moderate loss of specificity. Invasion of the seminal vesicles (T3b) occurs most often along the ejaculatory duct complex with low MR sensitivity.

ADVANCES IN KNOWLEDGE

Simplified MRI study at 1.5 T without endorectal coil could be used for the local T staging of prostate cancer.

Body diffusion kurtosis imaging: Basic principles, applications, and considerations for clinical practice

Technologic advances enable performance of diffusion-weighted imaging (DWI) at ultrahigh b-values, where standard monoexponential model analysis may not apply. Rather, non-Gaussian water diffusion properties emerge, which in cellular tissues are, in part, influenced by the intracellular environment that is not well evaluated by conventional DWI. The novel technique, diffusion kurtosis imaging (DKI), enables characterization of non-Gaussian water diffusion behavior. More advanced mathematical curve fitting of the signal intensity decay curve using the DKI model provides an additional parameter Kapp that presumably reflects heterogeneity and irregularity of cellular microstructure, as well as the amount of interfaces within cellular tissues. Although largely applied for neural applications over the past decade, a small number of studies have recently explored DKI outside the brain. The most investigated organ is the prostate, with preliminary studies suggesting improved tumor detection and grading using DKI. Although still largely in the research phase, DKI is being explored in wider clinical settings. When assessing extracranial applications of DKI, careful attention to details with which body radiologists may currently be unfamiliar is important to ensure reliable results. Accordingly, a robust understanding of DKI is necessary for radiologists to better understand the meaning of DKI-derived metrics in the context of different tumors and how these metrics vary between tumor types and in response to treatment. In this review, we outline DKI principles, propose biostructural basis for observations, provide a comparison with standard monoexponential fitting and the apparent diffusion coefficient, report on extracranial clinical investigations to date, and recommend technical considerations for implementation in body imaging.

Integrating diffusion kurtosis imaging, dynamic susceptibility-weighted contrast-enhanced MRI, and short echo time chemical shift imaging for grading gliomas

BACKGROUND

We assessed the diagnostic accuracy of diffusion kurtosis imaging (DKI), dynamic susceptibility-weighted contrast-enhanced (DSC) MRI, and short echo time chemical shift imaging (CSI) for grading gliomas.

METHODS

In this prospective study, 35 patients with cerebral gliomas underwent DKI, DSC, and CSI on a 3 T MR scanner. Diffusion parameters were mean diffusivity (MD), fractional anisotropy, and mean kurtosis (MK). Perfusion parameters were mean relative regional cerebral blood volume (rrCBV), mean relative regional cerebral blood flow (rrCBF), mean transit time, and relative decrease ratio (rDR). The diffusion and perfusion parameters along with 12 CSI metabolite ratios were compared among 22 high-grade gliomas and 14 low-grade gliomas (Mann-Whitney U-test, P < .05). Classification accuracy was determined with a linear discriminant analysis for each MR modality independently. Furthermore, the performance of a multimodal analysis is reported, using a decision-tree rule combining the statistically significant DKI, DSC-MRI, and CSI parameters with the lowest P-value. The proposed classifiers were validated on a set of subsequently acquired data from 19 clinical patients.

RESULTS

Statistically significant differences among tumor grades were shown for MK, MD, mean rrCBV, mean rrCBF, rDR, lipids over total choline, lipids over creatine, sum of myo-inositol, and sum of creatine. DSC-MRI proved to be the modality with the best performance when comparing modalities individually, while the multimodal decision tree proved to be most accurate in predicting tumor grade, with a performance of 86%.

CONCLUSIONS

Combining information from DKI, DSC-MRI, and CSI increases diagnostic accuracy to differentiate low- from high-grade gliomas, possibly providing diagnosis for the individual patient.

Comparison of digital breast tomosynthesis and 2D digital mammography using a hybrid performance test

This paper introduces a hybrid method for performing detection studies in projection image based modalities, based on image acquisitions of target objects and patients. The method was used to compare 2D mammography and digital breast tomosynthesis (DBT) in terms of the detection performance of spherical densities and microcalcifications. The method starts with the acquisition of spheres of different glandular equivalent densities and microcalcifications of different sizes immersed in a homogeneous breast tissue simulating medium. These target objects are then segmented and the subsequent templates are fused in projection images of patients and processed or reconstructed. This results in hybrid images with true mammographic anatomy and clinically relevant target objects, ready for use in observer studies. The detection study of spherical densities used 108 normal and 178 hybrid 2D and DBT images; 156 normal and 321 hybrid images were used for the microcalcifications. Seven observers scored the presence/absence of the spheres/microcalcifications in a square region via a 5-point confidence rating scale. Detection performance in 2D and DBT was compared via ROC analysis with sub-analyses for the density of the spheres, microcalcification size, breast thickness and z-position. The study was performed on a Siemens Inspiration tomosynthesis system using patient acquisitions with an average age of 58 years and an average breast thickness of 53 mm providing mean glandular doses of 1.06 mGy (2D) and 2.39 mGy (DBT). Study results showed that breast tomosynthesis (AUC = 0.973) outperformed 2D (AUC = 0.831) for the detection of spheres (p  <  0.0001) and this applied for all spherical densities and breast thicknesses. By way of contrast, DBT was worse than 2D for microcalcification detection (AUC2D = 0.974, AUCDBT = 0.838, p  <  0.0001), with significant differences found for all sizes (150-354 µm), for breast thicknesses above 40 mm and for heights above the detector of 20 mm and above. In conclusion, the hybrid method was successfully used to produce images for a detection study; results showed breast tomosynthesis outperformed 2D for spherical densities while further optimization of DBT for microcalcifications is suggested.

Three-dimensional analysis of implanted magnetic-resonance-visible meshes

OBJECTIVE

Our primary objective was to develop relevant algorithms for quantification of mesh position and 3D shape in magnetic resonance (MR) images.

METHODS

In this proof-of-principle study, one patient with severe anterior vaginal wall prolapse was implanted with an MR-visible mesh. High-resolution MR images of the pelvis were acquired 6 weeks and 8 months postsurgery. 3D models were created using semiautomatic segmentation techniques. Conformational changes were recorded quantitatively using part-comparison analysis. An ellipticity measure is proposed to record longitudinal conformational changes in the mesh arms. The surface that is the effective reinforcement provided by the mesh is calculated using a novel methodology. The area of this surface is the effective support area (ESA).

RESULTS

MR-visible mesh was clearly outlined in the images, which allowed us to longitudinally quantify mesh configuration between 6 weeks and 8 months after implantation. No significant changes were found in mesh position, effective support area, conformation of the mesh's main body, and arm length during the period of observation. Ellipticity profiles show longitudinal conformational changes in posterior arms.

CONCLUSIONS

This paper proposes novel methodologies for a systematic 3D assessment of the position and morphology of MR-visible meshes. A novel semiautomatic tool was developed to calculate the effective area of support provided by the mesh, a potentially clinically important parameter.

The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis

PURPOSE

This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images.

METHODS

Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses.

RESULTS

The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly suggestive for malignancy (BIRADS 5) indicating the required variety of shapes and margins of these models. The assessment of the BIRADS scores for all observers indicated good agreement based on Kendall's coefficient for both the 2D and the tomosynthesis evaluations. The paired analysis of the BIRADS scores between 2D and tomosynthesis for each observer revealed consistent behavior for the real and simulated masses.

CONCLUSIONS

A database of 3D mass models, with variety of shapes and margins, was validated for the realism of their appearance for 2D digital mammography and for breast tomosynthesis. This database is suitable for use in future observer performance studies whether in virtual clinical trials or in patient images with simulated lesions.

Integrating pretreatment diffusion weighted MRI into a multivariable prognostic model for head and neck squamous cell carcinoma

INTRODUCTION

In head and neck squamous cell carcinoma (HNSCC) the ability to anticipate an individual patient's outcome is very valuable. With this study we wanted to assess the prognostic value of pretreatment apparent diffusion coefficient (ADC) in a large patient population and integrate it into a multivariable prognostic model.

METHODS

From 2004 to 2010 175 patients with pathology proven HNSCC were included in this study. All patients underwent a pretreatment MRI with diffusion weighted imaging (DWI) using six b-values. For each tumor, three ADC values were calculated using different b-value combinations: ADC(low) (b 0-50-100 s/mm(2)), ADChigh (b 500-750-1000 s/mm(2)) and ADC(avg) (all b-values). The clinical and radiological variables included: tumor and nodal volume, tumor location and age. Disease recurrence was analyzed using competing risk regression. A prognostic model for disease recurrence was developed, and internal validation was performed using bootstrapping and by dividing patients in three equal sized groups based on prognosis.

RESULTS

One hundred and sixty-one patients were eligible for analysis. Median follow-up was 50 months (range 4-86). A total of 67 patients experienced disease recurrence during follow-up (42%). ADC(high) was a prognostic factor for disease recurrence (adjusted hazard ratio: 1.14 per 10(-4) mm(2)/s, 95% CI 1.04-1.25). Harrell's c-index of the multivariable prognostic model was 0.62 (95% CI 0.56-0.70) after internal validation. The validated 3-year disease recurrence rates for the groups with worst, intermediate, and best prognosis were 56%, 33% and 31% respectively.

CONCLUSION

Pretreatment ADC value derived from high b-values is an independent prognostic factor in HNSCC and increases the performance of a multivariable prognostic model in addition to known clinical and radiological variables. Integration of other biomarkers and external validation is necessary to ensure its clinical applicability.

Separate calculation of DW-MRI in assessing therapeutic effect in liver tumors in rats

AIM: To explore whether the antitumor effect of a vascular disrupting agent (VDA) would be enhanced by combining with an antiangiogenic agent, and whether such synergistic effects can be effectively evaluated with separate calculation of diffusion weighted magnetic resonance imaging (DW-MRI).

METHODS: Thirty-seven rats with implanted liver tumors were randomized into the following three groups: (1) ZD6126, a kind of VDA; (2) ZDTHA, ZD6126 in combination with an antiangiogenic, thalidomide; and (3) control. Morphological DW-MRI were performed and quantified before, 4 h and 2 d after treatment. The apparent diffusion coefficient (ADC) values were calculated separately for low b values (ADC_low), high b values (ADC_high) and all b values (ADC_all). The tissue perfusion contribution, ADC_perf, was calculated as ADC_low-ADC_high. Imaging findings were finally verified by histopathology.

RESULTS: The combination therapy with ZDTHA significantly delayed tumor growth due to synergistic effects by inducing cumulative tumor necrosis. In addition to delaying tumor growth, ZDTHA caused tumor necrosis in an additive manner, which was verified by HE staining. Although both ADC_high and ADC_all in the ZD6126 and ZDTHA groups were significantly higher compared to those in the control group on day 2, the entire tumor ADC_high of ZDTHA was even higher than that of ZD6126, but the significant difference was not observed for ADC_all between ZDTHA and ZD6126. This indicated that the perfusion insensitive ADC_high values calculated from high b value images performed significantly better than ADC_all for the monitoring of tumor necrosis on day 2. The perfusion sensitive ADC_perf derived from ADC_low by excluding high b value effects could better reflect the reduction of blood flow due to the vessel shutdown induced by ZD6126, compared to the ADC_low at 4 h. The ADC_perf could provide valuable perfusion information from DW-MRI data.

CONCLUSION: The separate calculation of ADC is more useful than conventional averaged ADC in evaluating the efficacy of combination therapy with ZD6126 and thalidomide for solid tumors.

Chemoembolization for hepatocellular carcinoma: 1-month response determined with apparent diffusion coefficient is an independent predictor of outcome

PURPOSE

To evaluate the predictive utility of apparent diffusion coefficient (ADC) changes at diffusion-weighted (DW) magnetic resonance (MR) imaging 1 month after transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) compared with the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, European Association for the Study of the Liver (EASL) criteria, and modified RECIST (mRECIST).

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained for this prospective study. Thirty-eight patients with inoperable HCC underwent 1.5-T MR imaging, including DW imaging, before and 1 month after TACE. Responses 1 month after TACE were assessed with the ADC change relative to baseline (ADC ratio), RECIST, EASL criteria, and mRECIST. Eight patients underwent transplantation 4 months after TACE, allowing the association between response and histopathologic necrosis ratio to be determined. In 30 patients, Kaplan-Meier and log-rank tests were used to correlate the response variables with progression-free and overall survival.

RESULTS

Median progression-free survival (PFS) was 5 months, and overall survival was 17.5 months. Survival analyses showed significant effects of pretreatment α-fetoprotein level (P = .03) and ADC ratio (P < .0001) on PFS and substantial effects of mRECIST, RECIST, and EASL criteria (.05 < P < .1). ADC ratio was a significant predictor of 5-month PFS (P < .001), with an accuracy of 93.3% compared with 53.3% with mRECIST and EASL criteria and 66.7% with RECIST. No response variables correlated with overall survival. Only the ADC ratio was significantly associated with histopathologic tumor necrosis (P = .03).

CONCLUSION

The ADC ratio 1 month after TACE was an independent predictor of PFS, which showed stronger association with tumor response than did RECIST, EASL criteria, or mRECIST.

Whole-body MRI with diffusion-weighted sequence for staging of patients with suspected ovarian cancer: a clinical feasibility study in comparison to CT and FDG-PET/CT

OBJECTIVES

To evaluate whole-body MRI with diffusion-weighted sequence (WB-DWI/MRI) for staging and assessing operability compared with CT and FDG-PET/CT in patients with suspected ovarian cancer.

METHODS

Thirty-two patients underwent 3-T WB-DWI/MRI, (18) F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and CT before diagnostic open laparoscopy (DOL). Imaging findings for tumour characterisation, peritoneal and retroperitoneal staging were correlated with histopathology after DOL and/or open surgery. For distant metastases, FDG-PET/CT or image-guided biopsies were the reference standards. For tumour characterisation and peritoneal staging, WB-DWI/MRI was compared with CT and FDG-PET/CT. Interobserver agreement for WB-DWI/MRI was determined.

RESULTS

WB-DWI/MRI showed 94 % accuracy for primary tumour characterisation compared with 88 % for CT and 94 % for FDG-PET/CT. WB-DWI/MRI showed higher accuracy of 91 % for peritoneal staging compared with CT (75 %) and FDG-PET/CT (71 %). WB-DWI/MRI and FDG-PET/CT showed higher accuracy of 87 % for detecting retroperitoneal lymphadenopathies compared with CT (71 %). WB-DWI/MRI showed excellent correlation with FDG-PET/CT (κ = 1.00) for detecting distant metastases compared with CT (κ = 0.34). Interobserver agreement was moderate to almost perfect (κ = 0.58-0.91).

CONCLUSIONS

WB-DWI/MRI shows high accuracy for characterising primary tumours, peritoneal and distant staging compared with CT and FDG-PET/CT and may be valuable for assessing operability in ovarian cancer patients.

KEY POINTS

• Whole-body MRI with diffusion weighting (WB-DWI/MRI) helps to assess the operability of suspected ovarian cancer. • Interobserver agreement is good for primary tumour characterisation, peritoneal and distant staging. • WB-DWI/MRI improves mesenteric/serosal metastatic spread assessment compared with CT and FDG-PET/CT. • Retroperitoneal/cervical-thoracic nodal staging using qualitative DWI criteria was reasonably accurate. • WB-DWI/MRI and FDG-PET/CT showed the highest diagnostic impact for detecting thoracic metastases.

Redefining the target early during treatment. Can we visualize regional differences within the target volume using sequential diffusion weighted MRI?

PURPOSE

In head and neck cancer, diffusion weighted MRI (DWI) can predict response early during treatment. Treatment-induced changes and DWI-specific artifacts hinder an accurate registration between apparent diffusion coefficient (ADC) maps. The aim of the study was to develop a registration tool which calculates and visualizes regional changes in ADC.

METHODS

Twenty patients with stage IV HNC treated with primary radiotherapy received an MRI including DWI before and early during treatment. Markers were manually placed at anatomical landmarks on the different modalities at both time points. A registration method, consisting of a fully automatic rigid and nonrigid registration and two semi-automatic thin-plate spline (TPS) warps was developed and applied to the image sets. After each registration step the mean registration errors were calculated and ΔADC was compared between good and poor responders.

RESULTS

Adding the TPS warps significantly reduced the registration error (in mm, 6.3 ± 6.2 vs 3.2 ± 3.3 mm, p<0.001). After the marker based registration the median ΔADC in poor responders was significantly lower than in good responders (7% vs. 21%; p<0.001).

CONCLUSIONS

This registration method allowed for a significant reduction of the mean registration error. Furthermore the voxel-wise calculation of the ΔADC early during radiotherapy allowed for a visualization of the regional differences of ΔADC within the tumor.

Whole-body diffusion-weighted magnetic resonance imaging at 3 Tesla for early assessment of treatment response in non-Hodgkin lymphoma: a pilot study

Objective: To evaluate 3 Tesla (T) whole-body diffusion-weighted magnetic resonance imaging (WB DWI) for early treatment assessment in aggressive non-Hodgkin lymphoma (NHL). Methods: Fourteen patients with NHL treated with standard chemotherapy underwent 3-T WB DWI before and 2 and 4 weeks during treatment, using b-values of 0–1000 s/mm² from which the apparent diffusion coefficient (ADC) was calculated. Patient follow-up (average 20.3 months, range 15–23 months) was the reference standard. Volume and ADC changes between baseline and 2 weeks (Vratio_2w, ADCratio_2w) and 4 weeks (Vratio_4w, ADCratio_4w) of responding and non-responding lesions (lymph node and organ lesions) were compared using Mann–Whitney U tests. The per patient values of Vratio_N and ADCratio_N to predict progression-free survival were determined with a log-rank test. Results: Eight patients showed complete remission and 6 showed tumour progression. The ADCratio_2w and ADCratio_4w differed significantly in lesions showing tumour progression versus complete remission (ADCratio_2w = 4 ± 21% versus 119 ± 68%; ADCratio_4w = 18 ± 61% versus 155 ± 78%; both P < 0.0001); the Vratio_2w and Vratio_4w did not (P > 0.05). Per body region, the ADCratio_2w showed a negative predictive value of 100% and positive predictive value of 86%. Per patient, the ADCratio_2w and ADCratio_4w correlated significantly with progression-free survival (P < 0.05). Conclusion: 3-T WB DWI with ADC quantification may enable early treatment assessment of aggressive NHL.

Diffusion-weighted MR imaging including bi-exponential fitting for the detection of recurrent or residual tumour after (chemo)radiotherapy for laryngeal and hypopharyngeal cancers

OBJECTIVES

To assess whether diffusion-weighted magnetic resonance imaging (DW-MRI) including bi-exponential fitting helps to detect residual/recurrent tumours after (chemo)radiotherapy of laryngeal and hypopharyngeal carcinoma.

METHODS

Forty-six patients with newly-developed/worsening symptoms after (chemo)radiotherapy for laryngeal/hypopharyngeal cancers were prospectively imaged using conventional MRI and axial DW-MRI. Qualitative (visual assessment) and quantitative analysis (mono-exponentially: total apparent diffusion coefficient [ADC(T)], and bi-exponentially: perfusion fraction [F(P)] and true diffusion coefficient [ADC(D)]) were performed. Diffusion parameters of tumour versus post-therapeutic changes were compared, with final diagnosis based on histopathology and follow-up. Mann-Whitney U test was used for statistical analysis.

RESULTS

Qualitative DW-MRI combined with morphological images allowed the detection of tumour with a sensitivity of 94% and specificity 100%. ADC(T) and ADC(D) values were lower in tumour with values 120 ± 49 × 10(-5) mm(2)/s and 113 ± 50 × 10(-5) mm(2)/s, respectively, compared with post-therapeutic changes with values 182 ± 41 × 10(-5) mm(2)/s (P < 0.0002) and 160 ± 47 × 10(-5) mm(2)/s (P < 0.003), respectively. F(P) values were significantly lower in tumours than in non-tumours (13 ± 9% versus 31 ± 16%, P < 0.0002), with F(P) being the best quantitative parameter for differentiation between post-therapeutic changes and recurrence.

CONCLUSIONS

DW-MRI in combination with conventional MRI substantially improves detection and exclusion of tumour in patients with laryngeal and hypopharyngeal cancers after treatment with (chemo)radiotherapy on both qualitative and quantitative analysis, with F(P) being the best quantitative parameter in this context.

Enhanced antitumor efficacy of a vascular disrupting agent combined with an antiangiogenic in a rat liver tumor model evaluated by multiparametric MRI

A key problem in solid tumor therapy is tumor regrowth from a residual viable rim after treatment with a vascular disrupting agent (VDA). As a potential solution, we studied a combined treatment of a VDA and antiangiogenic. This study was approved by the institutional ethical committee for the use and care of laboratory animals. Rats with implanted liver tumors were randomized into four treatment groups: 1) Zd6126 (Zd); 2) Thalidomide (Tha); 3) Zd in combination with Tha (ZdTha); and 4) controls. Multiparametric MRIs were performed and quantified before and after treatment. Circulating endothelial progenitor cells (EPCs) and plasma stromal cell-derived factor-1α (SDF-1α) were monitored. Tumor apoptosis, necrosis, and microvessels were verified by histopathology. A single use of Zd or Tha did not significantly delay tumor growth. The combined ZdTha showed enhanced antitumor efficacy due to synergistic effects; it induced a cumulative tumor apoptosis or necrosis, which resulted in significant delay in tumor growth and reduction in the viable tumor rim; it also reduced tumor vessel permeability; and it improved tumor hemodynamic indexes, most likely via a transient normalization of tumor vasculature induced by Tha. A stepwise linear regression analysis showed that the apparent diffusion coefficient was an independent predictor of tumor growth. We found no significant increases in Zd-induced circulating EPCs or plasma SDF-1α. ZdTha showed improved therapeutic efficacy in solid tumors compared to either agent alone. The therapeutic effects were successfully tracked in vivo with multiparametric MRI.

Diffusion-weighted MR imaging in the head and neck

Extracranial applications of diffusion-weighted (DW) magnetic resonance (MR) imaging are gaining increasing importance, including in head and neck radiology. The main indications for performing DW imaging in this relatively small but challenging region of the body are tissue characterization, nodal staging, therapy monitoring, and early detection of treatment failure by differentiating recurrence from posttherapeutic changes. Lower apparent diffusion coefficients (ADCs) have been reported in the head and neck region of adults and children for most malignant lesions, as compared with ADCs of benign lesions. For nodal staging, DW imaging has shown promise in helping detect lymph node metastases, even in small (subcentimeter) nodes with lower ADCs, as compared with normal or reactive nodes. Follow-up of early response to treatment is reflected in an ADC increase in the primary tumor and nodal metastases; whereas nonresponding lesions tend to reveal only a slight increase or even a decrease in ADC during follow-up. Optimization and standardization of DW imaging technical parameters, comparison of DW images with morphologic images, and increasing experience, however, are prerequisites for successful application of this challenging technique in the evaluation of various head and neck pathologic conditions.

Diffusion-weighted MR imaging of native and transplanted kidneys

Applications of diffusion-weighted (DW) magnetic resonance (MR) imaging outside the brain have gained increasing importance in recent years. Owing to technical improvements in MR imaging units and faster sequences, the need for noninvasive imaging without contrast medium administration, mainly in patients with renal insufficiency, can be met successfully by applying this technique. DW MR imaging is quantified by the apparent diffusion coefficient (ADC), which provides information on diffusion and perfusion simultaneously. By using a biexponential fitting process of the DW MR imaging data, these two entities can be separated, because this type of fitting process can serve as an estimate of both the perfusion fraction and the true diffusion coefficient. DW MR imaging can be applied for functional evaluation of the kidneys in patients with acute or chronic renal failure. Impairment of renal function is accompanied by a decreased ADC. Acute ureteral obstruction leads to perfusion and diffusion changes in the affected kidney, and renal artery stenosis results in a decreased ADC. In patients with pyelonephritis, diffuse or focal changes in signal intensity are seen on the high-b-value images, with increased signal intensity corresponding to low signal intensity on the ADC map. The feasibility and reproducibility of DW MR imaging in patients with transplanted kidneys have already been demonstrated, and initial results seem to be promising for the assessment of allograft deterioration. Overall, performance of renal DW MR imaging, presuming that measurements are of high quality, will further boost this modality, particularly for early detection of diffuse renal conditions, as well as more accurate characterization of focal renal lesions.

Diffusion-weighted magnetic resonance imaging early after chemoradiotherapy to monitor treatment response in head-and-neck squamous cell carcinoma

PURPOSE

To evaluate diffusion-weighted imaging (DWI) for assessment of treatment response in head and neck squamous cell carcinoma (HNSCC) three weeks after the end of chemoradiotherapy (CRT).

METHODS AND MATERIALS

Twenty-nine patients with HNSCC underwent magnetic resonance imaging (MRI) prior to and 3 weeks after CRT, including T(2)-weighted and pre- and postcontrast T(1)-weighted sequences and an echo-planar DWI sequence with six b values (0 to 1,000 s/mm(2)), from which the apparent diffusion coefficient (ADC) was calculated. ADC changes 3 weeks posttreatment compared to baseline (∆ADC) between responding and nonresponding primary lesions and adenopathies were correlated with 2 years locoregional control and compared with a Mann-Whitney test. In a blinded manner, the ∆ADC was compared to conventional MRI 3 weeks post-CRT and the routinely implemented CT, on average 3 months post-CRT, which used size-related and morphological criteria. Positive and negative predictive values (PPV and NPV, respectively) were compared between the ∆ADC and anatomical imaging.

RESULTS

The ∆ADC of lesions with later tumor recurrence was significantly lower than lesions with complete remission for both primary lesions (-2.3% ± 0.3% vs. 80% ± 41%; p < 0.0001) and adenopathies (19.9% ± 32% vs. 63% ± 36%; p = 0.003). The ∆ADC showed a PPV of 89% and an NPV of 100% for primary lesions and a PPV of 70% and an NPV of 96% for adenopathies per neck side. DWI improved PPV and NPV compared to anatomical imaging.

CONCLUSION

DWI with the ∆ADC 3 weeks after concluding CRT for HNSCC allows for early assessment of treatment response.

Value of diffusion-weighted magnetic resonance imaging for prediction and early assessment of response to neoadjuvant radiochemotherapy in rectal cancer: preliminary results

PURPOSE

To evaluate diffusion-weighted magnetic resonance imaging (DWI) for response prediction before and response assessment during and early after preoperative radiochemotherapy (RCT) for locally advanced rectal cancer (LARC).

METHODS AND MATERIALS

Twenty patients receiving RCT for LARC underwent MRI including DWI before RCT, after 10-15 fractions and 1 to 2 weeks before surgery. Tumor volume and apparent diffusion coefficient (ADC; b-values: 0-1000 s/mm(2)) were determined at all time points. Pretreatment tumor ADC and volume, tumor ADC change (∆ADC), and volume change (∆V) between pretreatment and follow-up examinations were compared with histopathologic findings after total mesorectal excision (pathologic complete response [pCR] vs. no pCR, ypT0-2 vs. ypT3-4, T-downstaging or not). The discriminatory capability of pretreatment tumor ADC and volume, ∆ADC, and ∆V for the detection of pCR was compared with receiver operating characteristics analysis.

RESULTS

Pretreatment ADC was significantly lower in patients with pCR compared with patients without (in mm(2)/s: 0.94 ± 0.12 × 10(-3) vs. 1.19 ± 0.22 × 10(-3), p = 0.003), yielding a sensitivity of 100% and specificity of 86% for detection of pCR. The volume reduction during and after RCT was significantly higher in patients with pCR compared with patients without (in %: ΔV(during): -62 ± 16 vs. -33 ± 16, respectively, p = 0.015; and ΔV(post): -86 ± 12 vs. -60 ± 21, p = 0.012), yielding a sensitivity of 83% and specificity of 71% for the ΔV(during) and, respectively, 83% and 86% for the ΔV(post). The ∆ADC during (ΔADC(during)) and after RCT (ΔADC(post)) showed a significantly higher value in patients with pCR compared with patients without (in %: ΔADC(during): 72 ± 14 vs. 16 ± 12, p = 0.0006; and ΔADC(post): 88 ± 35 vs. 26 ± 19, p = 0.0011), yielding a sensitivity and specificity of 100% for the ΔADC(during) and, respectively, 100% and 93% for the ΔADC(post).

CONCLUSIONS

These initial findings indicate that DWI, using pretreatment ADC, ΔADC(during), and ΔADC(post) may be useful for prediction and early assessment of pathologic response to preoperative RCT of LARC, with higher accuracy than volumetric measurements.

Examining the relationship between the lung-to-head ratio measured on ultrasound and lung volumetry by magnetic resonance in fetuses with isolated congenital diaphragmatic hernia

PURPOSE

In fetuses with isolated congenital diaphragmatic hernia (CDH), lung development can be measured by the lung-to-head ratio (LHR) using ultrasound as well as by lung volumetry determined by fetal magnetic resonance imaging (MRI). We aimed to investigate their relationship as well as to analyze the factors that may have an impact on it.

MATERIAL AND METHODS

In 153 consecutive fetuses with isolated CDH, both the LHR and total fetal lung volume (TFLV) were measured. The observed LHR was calculated by dividing the lung area by the head circumference. On MRI, planimetric measurements of ipsilateral, contralateral and TFLV were performed on T(2)-HASTE (half-Fourier acquisition single-shot turbo spin echo) sequences in transverse as well as coronal or sagittal planes. All values were expressed as a ratio of what was observed over what is expected in a gestational age-matched normal fetus. Secondary analyses were performed for right- versus left-sided hernia and for measurements made prior to 25 weeks' gestation. A multivariate linear regression approach was used to determine the influence of the independent variables such as observed/expected (O/E) LHR, gestational age, liver position and CDH side on the dependent variables O/E TFLV and O/E contralateral FLV, and to determine the optimal formulas for calculation of the O/E TFLV as well as contralateral FLV.

RESULTS

In total, 200 pairs of measurements were obtained between 20 and 37 weeks' gestation (median 26+6). There was a significant association between the O/E contralateral FLV and O/E LHR (R(2) = 0.44; p < 0.001) as well as between the O/E TFLV and the O/E LHR (R(2) = 0.37; p < 0.001). After adding the independent variables that were first shown to be significant on univariate analysis, the multiple regression analysis demonstrated that gestational age (p = 0.017) and side of the defect (p < 0.001) were predictive of O/E LHR (p < 0.001) and strongly improved the estimation of O/E TFLV (R(2) = 0.43 instead of 0.37 when using O/E LHR only). In terms of estimating O/E contralateral FLV, only the O/E LHR was a significant (p < 0.001) independent predictor (R(2) = 0.44). These correlations also applied when considering only left-sided CDH cases. For measurements done prior to the third trimester, the O/E LHR (p = 0.034), gestational age (p = 0.035) as well as liver herniation (p = 0.029) were significantly correlated to the O/E TFLV (R(2) = 0.33). In terms of predicting the O/E contralateral FLV (R(2) = 0.25), only O/E LHR (p = 0.008) and gestational age (p = 0.037) were useful predictors.

CONCLUSION

Measurement of the O/E LHR on ultrasound allows a good estimation of the O/E contralateral FLV as well as TFLV as measured by MRI. Whereas the additional parameters such as gestational age, liver position and side of the defect did not improve the estimation of the contralateral FLV, they did so for estimating the TFLV.