Diagnostic Accuracy of Quantitative Imaging Biomarkers in the Differentiation of Benign and Malignant Vertebral Lesions : Combination of Diffusion-Weighted and Proton Density Fat Fraction Spine MRI.

PURPOSE: To compare and combine the diagnostic performance of the apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) and proton density fat fraction (PDFF) derived from chemical-shift encoding (CSE)-based water-fat magnetic resonance imaging (MRI) for distinguishing benign and malignant vertebral bone marrow lesions (VBML). METHODS: A total of 55 consecutive patients with 53 benign (traumatic, inflammatory and primary) and 36 malignant (metastatic and hematologic) previously untreated VBMLs were prospectively enrolled in this IRB-approved study and underwent sagittal DWI (single-shot spin-echo echo-planar with multi-slice short TI inversion recovery fat suppression) and CSE-based MRI (gradient-echo 6­point modified Dixon) in addition to routine clinical spine MRI at 1.5 T or 3.0 T. Diagnostic reference standard was established according to histopathology or imaging follow-up. The ADC = ADC (0, 800) and PDFF = fat / (water + fat) were calculated voxel-wise and examined for differences between benign and malignant lesions. RESULTS: The ADC and PDFF values of malignant lesions were significantly lower compared to benign lesions (mean ADC 861â€¯× 10-6 mm2/s vs. 1323â€¯× 10-6 mm2/s, p < 0.001; mean PDFF 3.1% vs. 28.2%, p < 0.001). The areas under the curve (AUC) and diagnostic accuracies were 0.847 (p < 0.001) and 85.4% (cut-off at 1084.4â€¯× 10-6 mm2/s) for ADC and 0.940 (p < 0.001) and 89.9% for PDFF (cut-off at 7.8%), respectively. The combined use of ADC and PDFF improved the diagnostic accuracy to 96.6% (malignancy if ADC ≤ 1118.2â€¯× 10-6 mm2/s and PDFF ≤ 20.0%, otherwise benign). CONCLUSION: Quantitative evaluation of both ADC and PDFF was useful in differentiating benign VBMLs from malignancy. The combination of ADC and PDFF improved the diagnostic performance and yielded high diagnostic accuracy for the differentiation of benign and malignant VBMLs.

Proton density fat fraction MRI of vertebral bone marrow: Accuracy, repeatability, and reproducibility among readers, field strengths, and imaging platforms.

BACKGROUND: Chemical shift-encoding based water-fat MRI is an emerging method to noninvasively assess proton density fat fraction (PDFF), a promising quantitative imaging biomarker for estimating tissue fat concentration. However, in vivo validation of PDFF is still lacking for bone marrow applications. PURPOSE: To determine the accuracy and precision of MRI-determined vertebral bone marrow PDFF among different readers and across different field strengths and imager manufacturers. STUDY TYPE: Repeatability/reproducibility. SUBJECTS: Twenty-four adult volunteers underwent lumbar spine MRI with one 1.5T and two different 3.0T MR scanners from two vendors on the same day. FIELD STRENGTH/SEQUENCE: 1.5T and 3.0T/3D spoiled-gradient echo multipoint Dixon sequences. ASSESSMENT: Two independent readers measured intravertebral PDFF for the three most central slices of the L1-5 vertebral bodies. Single-voxel MR spectroscopy (MRS)-determined PDFF served as the reference standard for PDFF estimation. STATISTICAL TESTS: Accuracy and bias were assessed by Pearson correlation, linear regression analysis, and Bland-Altman plots. Repeatability and reproducibility were evaluated by Wilcoxon signed rank test, Friedman test, and coefficients of variation. Intraclass correlation coefficients were used to validate intra- and interreader as well as intraimager agreements. RESULTS: MRI-based PDFF estimates of lumbar bone marrow were highly correlated (r2 = 0.899) and accurate (mean bias, -0.6%) against the MRS-determined PDFF reference standard. PDFF showed high linearity (r2 = 0.972-0.978) and small mean bias (0.6-1.5%) with 95% limits of agreement within ±3.4% across field strengths, imaging platforms, and readers. Repeatability and reproducibility of PDFF were high, with the mean overall coefficient of variation being 0.86% and 2.77%, respectively. The overall intraclass correlation coefficient was 0.986 as a measure for an excellent interreader agreement. DATA CONCLUSION: MRI-based quantification of vertebral bone marrow PDFF is highly accurate, repeatable, and reproducible among readers, field strengths, and MRI platforms, indicating its robustness as a quantitative imaging biomarker for multicentric studies. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1762-1772.

Quantitative evaluation of T2* relaxation times for the differentiation of acute benign and malignant vertebral body fractures.

OBJECTIVES: The aim of this prospective study was to evaluate the diagnostic performance of T2*-weighted magnetic resonance imaging (MRI) to differentiate between acute benign and neoplastic vertebral compression fractures (VCFs). MATERIALS AND METHODS: Thirty-seven consecutive patients with a total of 52 VCFs were prospectively enrolled in this IRB approved study. All VCFs were categorized as either benign or malignant according to direct bone biopsy and histopathologic confirmation. In addition to routine clinical spine MRI including at least sagittal T1-weighted, T2-weighted and T2 spectral attenuated inversion recovery (SPAIR)-weighted sequences, all patients underwent an additional sagittal six-echo modified Dixon gradient-echo sequence of the spine at 3.0-T. Intravertebral T2* and T2*ratio (fracture T2*/normal vertebrae T2*) for acute benign and malignant VCFs were calculated using region-of-interest analysis and compared between both groups. Additional receiver operating characteristic analyses were performed. Five healthy subjects were scanned three times to determine the short-term reproducibility of vertebral T2* measurements. RESULTS: There were 27 acute benign and 25 malignant VCFs. Both T2* and T2*ratio of malignant VCFs were significantly higher compared to acute benign VCFs (T2*, 30 ± 11 vs. 19 ± 11 ms [p = 0.001]; T2*ratio, 2.9 ± 1.6 vs. 1.2 ± 0.7 [p < 0.001]). The areas under the curve were 0.77 for T2* and 0.88 for T2*ratio, yielding an accuracy of 73% and 89% for distinguishing acute benign from malignant VCFs. The root mean square absolute precision error was 0.44 ms as a measure for the T2* short-term reproducibility. CONCLUSION: Quantitative assessment of vertebral bone marrow T2* relaxation times provides good diagnostic accuracy for the differentiation of acute benign and malignant VCFs.

Proton density fat fraction (PDFF) MR imaging for differentiation of acute benign and neoplastic compression fractures of the spine.

OBJECTIVES: To evaluate the diagnostic performance of proton density fat fraction (PDFF) magnetic resonance imaging (MRI) to differentiate between acute benign and neoplastic vertebral compression fractures (VCFs). METHODS: Fifty-seven consecutive patients with 46 acute benign and 41 malignant VCFs were prospectively enrolled in this institutional review board approved study and underwent routine clinical MRI with an additional six-echo modified Dixon sequence of the spine at a clinical 3.0-T scanner. All fractures were categorised as benign or malignant according to either direct bone biopsy or 6-month follow-up MRI. Intravertebral PDFF and PDFFratio (fracture PDFF/normal vertebrae PDFF) for benign and malignant VCFs were calculated using region-of-interest analysis and compared between both groups. Additional receiver operating characteristic and binary logistic regression analyses were performed. RESULTS: Both PDFF and PDFFratio of malignant VCFs were significantly lower compared to acute benign VCFs [PDFF, 3.48 ± 3.30% vs 23.99 ± 11.86% (p < 0.001); PDFFratio, 0.09 ± 0.09 vs 0.49 ± 0.24 (p < 0.001)]. The areas under the curve were 0.98 for PDFF and 0.97 for PDFFratio, yielding an accuracy of 96% and 95% for differentiating between acute benign and malignant VCFs. PDFF remained as the only imaging-based variable to independently differentiate between acute benign and malignant VCFs on multivariate analysis (odds ratio, 0.454; p = 0.005). CONCLUSIONS: Quantitative assessment of PDFF derived from modified Dixon water-fat MRI has high diagnostic accuracy for the differentiation of acute benign and malignant vertebral compression fractures. KEY POINTS: • Chemical-shift-encoding based water-fat MRI can reliably assess vertebral bone marrow PDFF • PDFF is significantly higher in acute benign than in malignant VCFs • PDFF provides high accuracy for differentiating acute benign from malignant VCFs.

Hippocampal "gliosis only" on MR imaging represents a distinct entity in epilepsy patients.

PURPOSE: The purpose of this study is to evaluate whether patients with drug-resistant mesial temporal lobe epilepsy (TLE) due to hippocampal "gliosis only" have different MRI features than those with hippocampal sclerosis (HS). Most TLE patients have HS corresponding to severe neuronal loss and gliosis, but a few have "gliosis only" without significant reduction of neuronal density. METHODS: We analyzed the morphology of cerebral 3 T MRIs (T1, T2, and FLAIR) of 103 patients with HS and 20 with "gliosis only" concerning hippocampal and amygdala aspect, volumes, and signal intensity (SI) using Fisher's exact test, Student's t test, and principal component analysis. RESULTS: Visually, the ipsilateral hippocampus was hyperintense in both groups, but SI was markedly increased in 74% of HS and in 25% of "gliosis only" patients; the ipsilateral hippocampus was smaller in 92% of HS and in 50% of "gliosis only" patients, and its internal architecture was lost in 57% of HS and 5% of "gliosis only" patients; the contralateral hippocampal SI was altered in 25% of HS and in 70% of "gliosis only" patients (all p < 0.001). Ipsilateral hippocampus of HS patients had lower volume (mean ± SD 2.86 ± 0.87 ml) compared with that of "gliosis only" patients (3.4 ± 1.02 ml) and had higher SI than the contralateral hippocampus of HS patients and then the hippocampus of "gliosis only" patients (all p < 0.01). CONCLUSION: "Gliosis only" has different MRI hippocampal characteristics than HS: less volume loss, less increase of the T2-w signal intensity, preservation of internal architecture, and more contralateral affection.

Yttrium-90 radioembolization of unresectable hepatocellular carcinoma - a single center experience.

PURPOSE: To determine the value of radioembolization (RE) for treatment of unresectable hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Records of patients undergoing RE for unresectable HCC were retrospectively reviewed. Biochemical and clinical toxicities, imaging response (according to modified Response Evaluation Criteria In Solid Tumors), time-to-progression (TTP) and overall survival (OS) were analyzed. Data were stratified according to clinical and procedural parameters. Univariate and multivariate analyses were performed. RESULTS: One hundred and fifteen patients (89 male, mean age 69.3 years) underwent 158 REs (119 resin-, 39 glass-based) (Barcelona Clinic Liver Cancer [BCLC]-A: 6.1%, B: 33.9%, C: 60.0%). Median clinical follow-up was 5.9 (0.9-83.5) months. No grade 4 or 5 clinical toxicities were noted. Objective response rate was 35.6%; disease control rate was 76.7%. Median TTP of the treated part of the liver was 4 (0.9-45.4) months. 108/115 patients died during follow-up (median OS 8.4 [0.3-82.8] months after first RE [BCLC-A: 52.8 months, BCLC-B: 12.4 months, BCLC-C: 6.1 months]). On multivariate analysis, baseline Eastern Co-operative Oncology Group status <1, ascites prior to RE and best imaging response were predictors of longer OS. In BCLC-C patients, tumor burden, ascites prior to RE, baseline gamma-glutamyltransferase and Child-Pugh score were predictive of OS. CONCLUSIONS: RE is safe and effective in carefully selected patients suffering from HCC with a low complication rate. Low baseline Eastern Co-operative Oncology Group status and absence of ascites prior to RE are positive prognostic factors.

Incidentally Detected Focal Liver Lesions - A Common Clinical Management Dilemma Revisited.

BACKGROUND: Detection of asymptomatic focal liver lesions (FLL) is increasing because of a widespread use of modern radiologic imaging. Most of these lesions are benign, though malignancy often has to be ruled out, which is posing a diagnostic challenge. AIM: To critically evaluate our treatment strategy in the context of recently published American College of Gastroenterology (ACG) guidelines. PATIENTS AND METHODS: The medical records of patients who underwent surgery for asymptomatic, incidentally detected FLL from 2005-2012 were reviewed. Primary end-points were the congruence of suspected diagnosis and final pathology, as well as the identification of predictors of malignancy. A systematic review was undertaken to help define a standardized management. RESULTS: Eighty patients, 37 male and 43 female with a mean age of 57 years (range=16-83) were included, harboring 39 (49%) malignant and 41 (51%) benign, asymptomatic hepatic lesions. Hepatocellular carcinoma (HCC) (n=24) represented most of malignant FLL, followed by cholangiocellular carcinoma (CCC) (n=10), whereas focal nodular hyperplasia (FNH) (n=19) and liver hemangioma (n=7) were the predominant benign entities. Fifty-one patients (64%) had a correct preoperative diagnosis, while patients with FNH were most commonly misdiagnosed (53%). We identified age (p<0.001) and male sex (p=0.013) as risk factors for malignancy in an asymptomatic FLL. CONCLUSION: Despite recent technical advances of the modern radiology setting a correct preoperative diagnosis in an asymptomatic FLL remains challenging. Male gender and old age seem to correlate with malignancy. In the absence of biomarkers and evidence-based guidelines, a multidisciplinary approach in an experienced tertiary referral center is recommended for an optimized individual management.