Lorenzo Mannelli

Renal Lesions: Characterization with Diffusion-weighted Imaging versus Contrast-enhanced MR Imaging

PURPOSEnTo compare the diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging with that of contrast material-enhanced (CE) MR imaging and to assess the performance of these examinations combined for the characterization of renal lesions, with MR follow-up and histopathologic analysis as the reference standards.nnnMATERIALS AND METHODSnThe institutional review board waived the requirement of informed patient consent for this retrospective HIPAA-compliant study. One hundred nine renal lesions in 64 patients (46 men, 18 women; mean age, 60.7 years) were evaluated with CE MR imaging and breath-hold DW imaging performed with various b values. Renal lesions were characterized with use of CE MR criteria, and apparent diffusion coefficients (ADCs) were measured. The ADCs of benign and malignant lesions were compared at Mann-Whitney testing. Receiver operating characteristic (ROC) analysis was performed to assess the accuracy of DW imaging and CE MR imaging in the diagnosis of renal cell carcinoma (RCC).nnnRESULTSnThe 109 renal lesions--81 benign lesions and 28 RCCs--had a mean diameter of 4.2 cm +/- 2.5 (standard deviation). The mean ADC for RCCs (1.41 x 10(-3) mm(2)/sec +/- 0.61) was significantly lower (P < .0001) than that for benign lesions (2.23 x 10(-3) mm(2)/sec +/- 0.87) at DW imaging performed with b values of 0, 400, and 800 sec/mm(2). At a cutoff ADC of less than or equal to 1.92 x 10(-3) mm(2)/sec, the area under the ROC curve (AUC), sensitivity, and specificity of DW imaging for the diagnosis of RCCs (excluding angiomyolipomas) were 0.856, 86%, and 80%, respectively. The corresponding AUC, sensitivity, and specificity of CE MR imaging were 0.944, 100%, and 89%, respectively. Combined DW and CE MR imaging had 96% specificity. The AUC for the DW imaging-based diagnosis of solid RCC versus oncocytoma was 0.854. Papillary RCCs had lower ADCs than nonpapillary RCCs.nnnCONCLUSIONnDW imaging can be used to characterize renal lesions; however, compared with CE MR imaging, it is less accurate. DW imaging can be used to differentiate solid RCCs from oncocytomas and characterize the histologic subtypes of RCC.

Assessment of Tumor Necrosis of Hepatocellular Carcinoma After Chemoembolization: Diffusion-Weighted and Contrast-Enhanced MRI With Histopathologic Correlation of the Explanted Liver

OBJECTIVEnThe purpose of this study was to compare, with histopathologic examination of the liver explant as the reference standard, diffusion-weighted MRI with contrast-enhanced subtraction MRI in the assessment of necrosis of hepatocellular carcinoma (HCC) after trans arterial chemoembolization (TACE).nnnMATERIALS AND METHODSnThe cases of 21 patients with HCC who underwent MRI after TACE were evaluated. Two independent observers calculated the apparent diffusion coefficient (ADC) of HCC and measured percentage tumor necrosis on subtraction images. The ADCs of necrotic and viable tumor tissues were compared. ADC and percentage necrosis on subtraction images were correlated with percentage necrosis found at pathologic examination. Receiver operating characteristics analysis was performed on the diagnosis of complete tumor necrosis.nnnRESULTSnTwenty-eight HCCs (mean diameter, 2.3 cm) were evaluated. There were significant differences between the ADC of viable tissue and that of necrotic tumor tissue (1.33 +/- 0.41 vs 2.04 +/- 0.38 x 10(-3) mm(2)/s, p < 0.0001). There was significant moderate correlation between ADC and the pathologic finding of percentage necrosis (r = 0.64, p < 0.001) and significant strong correlation between subtraction image and pathologic percentage necrosis (r = 0.89-0.91, depending on the phase; p < 0.001). In the diagnosis of complete tumor necrosis, ADC had an area under the curve, sensitivity, and specificity of 0.85, 75%, and 87.5% compared with 0.82-0.89, 100%, and 58.3-79.1% for subtraction imaging (p > 0.5 between ADC and subtraction imaging).nnnCONCLUSIONnCompared with diffusion-weighted imaging, contrast-enhanced MRI with subtraction technique had more significant correlation with the histopathologic findings in the evaluation of necrosis of HCC after TACE. There was no difference, however, between the two methods in diagnosis of complete tumor necrosis.

Diagnosis of liver metastases: value of diffusion-weighted MRI compared with gadolinium-enhanced MRI.

ObjectiveThe full diagnostic value of diffusion-weighted (DW) MRI in the evaluation of liver metastases remains uncertain. The aim of the present study was to assess the diagnostic accuracy of DW-MRI and contrast-enhanced MRI (CE-MRI) using extracellular gadolinium chelates, with the reference standard established by consensus interpretation of confirmatory imaging and histopathologic data.MethodsMR examinations of 51 patients with extrahepatic malignancies were retrospectively reviewed by two independent observers who assessed DW-MRI and CE-MRI for detection of liver metastases.ResultsBy reference standard, 93 liver lesions (49 metastases and 44 benign lesions) were identified in 27 patients, 11 patients had no liver lesions, and 13 patients had innumerable metastatic and/or benign lesions. There was no difference in diagnostic performance between the two methods for either observer for the diagnosis of metastatic lesions per patient. For per-lesion analysis, sensitivity of DW-MRI was equivalent to CE-MRI for observer 1 (67.3% vs. 63.3%, pu2009=u20090.67), but lower for observer 2 (65.3% vs. 83.7%, pu2009=u20090.007). By pooling data from both observers, the sensitivity of DW-MRI was 66.3% (65/98) and 73.5% (72/98) for CE-MRI, with no significant difference (pu2009=u20090.171).ConclusionDW-MRI is a reasonable alternative to CE-MRI for the detection of liver metastases.

Hepatocellular carcinoma: assessment of response to transarterial chemoembolization with image subtraction.

To assess the diagnostic accuracy of image subtraction compared with nonsubtracted images obtained with contrast‐enhanced T1‐weighted imaging (CE T1WI) for the diagnosis of hepatocellular carcinoma (HCC) necrosis after transarterial chemoembolization (TACE), using liver explant as the reference standard.

Prostate cancer: utility of fusion of T2-weighted and high b-value diffusion-weighted images for peripheral zone tumor detection and localization.

To retrospectively assess the utility of fusion of T2‐weighted images (T2WI) and high b‐value diffusion‐weighted images (DWI) for prostate cancer detection and localization.

Liver Stiffness Assessment by Tagged MRI of Cardiac-induced Liver Motion

Cirrhosis is an important and growing public health problem, affecting millions of Americans and many more people internationally. A pathological hallmark of the progression to cirrhosis is the development of liver fibrosis, so that monitoring the appearance and progression of liver fibrosis can be used to guide therapy. Here, we report a method to use magnetization‐tagged magnetic resonance imaging to measure the cardiac‐induced motion and deformation in the liver, as a means for noninvasively assessing liver stiffness, which is related to fibrosis. The initial results show statistically significant differences between healthy and cirrhotic subjects in the direct comparisons of the maximum displacement (mm), and the maximum (P1) and minimum (P2) two‐dimensional strains, through the cardiac cycle (3.514 ± 0.793, 2.184 ± 0.611; 0.116 ± 0.043, 0.048 ± 0.011; −0.094 ± 0.020, −0.041 ± 0.015; healthy, cirrhosis, respectively; P < 0.005 for all). There are also significant differences in the displacement‐normalized P1 and P2 strains (mm−1) (0.030 ± 0.008, 0.017 ± 0.007; −0.024 ± 0.006, −0.013 ± 0.004; healthy, cirrhosis, respectively; P < 0.005 for all). Therefore, this noninvasive imaging‐based method is a promising means to assess liver stiffness using clinically available imaging tools. Magn Reson Med, 2011.

MR Elastography: Spleen Stiffness Measurements in Healthy Volunteers—Preliminary Experience

OBJECTIVEnThe purpose of this article is to establish the range of normal splenic stiffness in healthy volunteers using MR elastography (MRE) and to investigate any correlation with physiologic parameters and driver position.nnnSUBJECTS AND METHODSnSixteen volunteers (mean [+/- SD] age, 37 +/- 9 years) with no history of gastrointestinal, hepatobiliary, or cardiovascular disease were recruited. The MRI protocol included T2-weighted axial and gradient-echo MRE sequences using steady-state 60-Hz excitation. Two MRE acquisitions were performed, one with the driver placed on the right side of the abdomen and the other with the driver placed on the left side. Volunteers body mass index (BMI), arterial mean blood pressure, age, spleen volume, and liver stiffness were also determined. Two radiologists independently measured the spleen stiffness on the MRE inversion images. The correlations between spleen stiffness and BMI, arterial mean blood pressure, age, spleen volume, and liver stiffness were quantified.nnnRESULTSnSixteen volunteers underwent MRE. With the driver placed on the right side of the abdomen, the mean splenic stiffness was 3,565 +/- 586 Pa (range, 2,353-4,442 Pa); with the driver on the left side of the abdomen, the mean splenic stiffness was significantly (p < 0.004) different (4,255 +/- 625 Pa; range, 3,194-5,581 Pa). No significant correlation was found between spleen stiffness and BMI, arterial mean blood pressure, age, spleen volume, and liver stiffness (all p > 0.05)nnnCONCLUSIONnThese preliminary results in a small number of healthy volunteers show that spleen stiffness is not significantly correlated with BMI, arterial mean blood pressure, spleen volume, or liver stiffness. A significant difference was observed using different driver positions.

Evaluation of nonenhancing tumor fraction assessed by dynamic contrast-enhanced MRI subtraction as a predictor of decrease in tumor volume in response to chemoradiotherapy in advanced cervical cancer.

OBJECTIVEnIn this study, we evaluated the feasibility of using dynamic contrast-enhanced MRI (DCE-MRI) subtracted images as a predictor of a decrease in tumor volume in response to chemoradiotherapy in 13 patients with cervical cancer.nnnCONCLUSIONnThis study shows that pretreatment tumor nonenhancing fraction assessed with arterial image subtraction inversely predicts the chemoradiation response in cervical cancer.

Breath-hold T2-weighted MRI of the liver at 3 T using the BLADE technique: impact upon image quality and lesion detection

AIMnTo compare image quality and lesion detection in the liver using magnetic resonance imaging (MRI) at 3T between T2-weighted imaging using a standard rectilinear k-space trajectory (standard T2WI) and using the BLADE technique (BLADE-T2WI), a technique that employs periodically rotated overlapping parallel lines with enhanced reconstruction for motion correction.nnnMATERIALS AND METHODSnTwenty-eight consecutive patients who underwent MRI examination of the liver at 3T including standard T2WI and BLADE-T2WI, both performed using multiple breath-holds, comprised the study cohort. Images were reviewed in consensus by two radiologists during separate sessions for a number of measures regarding artefacts and image quality. These two readers also assessed the two image sets for the presence of liver lesions and measured liver-to-lesion contrast. Binary logistic regression for correlated data was used to compare the sequences in terms of sensitivity and positive predictive value (PPV) for lesion detection.nnnRESULTSnBLADE-T2WI received significantly higher scores than did standard T2WI for in-plane respiratory motion (p=0.0195), other ghosting artefacts (p<0.0001), sharpness of the liver edge (p=0.0004), sharpness of intra-hepatic vessels (p<0.0001), flow signal suppression (p<0.0001), and overall image quality (p<0.0001). There was a non-significant trend toward improved B(1)-inhomogeneity artefact with BLADE-T2WI (p=0.0571). There was no difference in through-plane respiratory motion (p=0.6836). BLADE-T2WI demonstrated a significant improvement in PPV for lesion detection (p=0.0129) as well as in liver-to-lesion contrast (p=0.0054). There was no difference regarding lesion sensitivity (p=1.0).nnnCONCLUSIONSnUse of the BLADE technique for T2-weighted MRI of the liver at 3T may lead to a significant improvement in image artefacts and improved PPV for lesion detection.

The value of postoperative/preadjuvant chemotherapy computed tomography in the management of patients with ovarian cancer.

Objective: The objectives of the study were to compare the operative assessment of residual disease with the postoperative computed tomography (CT) findings in patients with ovarian cancer who underwent primary surgical cytoreduction or interval debulking surgery to residual disease 1 cm or less and to assess the effect of potential prognostic factors on patient survival. Methods: Patients scheduled for surgery and with an available postoperative CT were eligible for the study. Images were retrospectively analyzed in consensus by 2 radiologists. A 5-point qualitative scoring system was used to evaluate the CT findings (1 = tumor definitely absent, 2 = tumor probably absent, 3 = tumor possibly present, 4 = tumor probably present, 5 = tumor definitely present). Results: Between September 2005 and December 2008, 206 consecutive patients were enrolled; 51 were eligible. In 30 cases (59%), the postoperative CT findings correlated with the surgeons assessment of residual disease. For the univariate analyses, the only significant prognostic factors associated with overall survival were no residual disease versus residual disease of less than 1 cm as assessed by the surgeon (hazard ratio [HR], 3.06; 95% confidence interval [CI], 1.29-7.27; P = 0.011) and no residual disease versus residual disease greater than 1 cm on CT (HR, 2.57; 95% CI, 1.02-6.48; P = 0.045). The interaction of surgical residual disease and stage 3 was significant (HR, 3.40; 95% CI, 1.42-8.16; P = 0.006) in the multivariate Cox model. Conclusions: There was only 59% correlation between the surgical assessment and postoperative CT findings of residual disease in patients reported to have undergone optimal surgery. Stage and residual disease as assessed by the surgeon were significant prognostic factors for overall survival. The value for postoperative CT may lie in those cases with small-volume residual disease (visible but reported as <1 cm) at surgery.