New OPTN/UNOS classification system for nodules in cirrhotic livers detected with MR imaging: effect on hepatocellular carcinoma detection and transplantation allocation.

PURPOSE: To assess the effect of the new Organ Procurement and Transplantation Network (OPTN)/United Network for Organ Sharing (UNOS) policy on hepatocellular carcinoma (HCC) detection and liver transplant allocation in patients with cirrhosis undergoing dynamic contrast material-enhanced liver magnetic resonance (MR) imaging. MATERIALS AND METHODS: In this HIPAA-compliant institutional review board-approved retrospective study with waiver of informed consent, 247 patients (196 men, 51 women; mean age, 60 years ± 11 [standard deviation]) with liver cirrhosis who underwent evaluation for HCC with MR imaging were identified via database search. Three radiologists independently reviewed images and identified number and size of HCC based on criteria within either the prior or revised policy. Based on these interpretations, priority for liver transplantation for each patient was determined with prior and revised transplantation allocation criteria. HCC detection was compared between sessions by using McNemar tests, and interreader agreement for detection of at least one HCC was assessed by using κ coefficients. RESULTS: All three readers detected significantly more 1-2-cm HCCs with the revised policy (readers detected 22, eight, and 20 1-2-cm HCCs) versus the prior policy (no reader detected 1-2-cm HCCs) (P ≤ .031). All readers detected significantly fewer 2-5-cm HCCs with the revised policy (readers detected eight, 13, and 14 2-5-cm HCCs) versus the prior policy (readers detected 24, 21, and 24 2-5-cm HCCs) (P ≤ .027). For all readers, fewer patients met criteria for increased transplantation priority with the revised versus the prior policy (number of patients who received increased priority for the three readers were 4.9% [12 of 247] vs 9.3% [23 of 247]; 5.7% [14 of 247] vs 8.1% [20 of 247]; and 6.9% [17 of 247] vs 8.9% [22 of 247]). Interreader agreement was substantial for the prior policy (κ = 0.607) and almost perfect for the revised policy (κ = 0.813). CONCLUSION: Among cirrhotic patients who underwent evaluation for HCC with MR imaging, the revised OPTN/UNOS policy led to increased detection of 1-2-cm HCCs, decreased detection of 2-5-cm HCCs, and fewer patients who met criteria for increased transplant priority.

Whole-lesion apparent diffusion coefficient metrics as a marker of percentage Gleason 4 component within Gleason 7 prostate cancer at radical prostatectomy.

PURPOSE: To retrospectively assess the utility of whole-lesion apparent diffusion coefficient (ADC) metrics in characterizing the Gleason 4 component of Gleason 7 prostate cancer (PCa) at radical prostatectomy. MATERIALS AND METHODS: Seventy patients underwent phased-array coil 3T-magnetic resonance imaging (MRI) before prostatectomy. A uropathologist mapped locations and Gleason 4 percentage (G4%) of Gleason 7 tumors. Two radiologists independently reviewed ADC maps, aware of tumor locations but not G4%, and placed a volume-of-interest (VOI) on all slices including each lesion on the ADC map to obtain whole-lesion mean ADC and ADC entropy. Entropy reflects textural variation and increases with greater macroscopic heterogeneity. Performance for characterizing Gleason 7 tumors was assessed with mixed-model analysis of variance (ANOVA) and logistic regression. RESULTS: Among 84 Gleason 7 tumors (G4% 5%-85%, median 30%; 59 Gleason 3+4, 25 Gleason 4+3), ADC entropy was significantly higher in Gleason 4+3 than Gleason 3+4 tumors (R1: 5.27 ± 0.61 vs. 4.62 ± 0.78, P = 0.001; R2: 5.91 ± 0.32 vs. 5.57 ± 0.56, P = 0.004); mean ADC was not significantly different between these groups (R1: 0.90 ± 0.15*10(-3) cm(2) /s vs. 0.98 ± 0.21*10(-3) cm(2) /s, P = 0.075; R2: 1.06 ± 0.19*10(-3) cm(2) /s vs. 1.14 ± 0.16*10(-3) cm(2) /s, P = 0.083). The area under the receiver operating characteristic (ROC) curve (AUC) for differentiating groups was significantly higher with ADC entropy than mean ADC for one observer (R1: 0.74 vs. 0.57, P = 0.027; R2: 0.69 vs. 0.61, P = 0.329). For R1, correlation with G4% was moderate for ADC entropy (r = 0.45) and weak for mean ADC (r = -0.25). For R2, correlation with G4% was moderate for ADC entropy (r = 0.41) and mean ADC (r = -0.32). For both readers, ADC entropy (P = 0.028-0.003), but not mean ADC (P = 0.384-0.854), was a significant independent predictor of G4%. CONCLUSION: Whole-lesion ADC entropy outperformed mean ADC in characterizing Gleason 7 tumors and may help refine prognosis for this heterogeneous PCa subset.

Zoomed echo-planar imaging using parallel transmission: impact on image quality of diffusion-weighted imaging of the prostate at 3T.

PURPOSE: To assess impact of two-channel parallel transmission (pTx) with focused excitation [zoomed echo-planar imaging (EPI)] on image quality of prostate diffusion-weighted imaging (DWI) at 3T. METHODS: 27 male volunteers (27 ± 8 years) underwent 3T prostate MRI using 2-channel radiofrequency-transmit system and 18-channel torso receive coil. Scans included EPI-DWI sequence (b values 50, 500, 1000 s/mm(2)) acquired both with standard sinc pulse and 2-channel pTX with focused excitation, each acquired at large-field-of-view (FOV) (20 × 20 cm) and small-FOV (14 × 14 cm). An abdominal radiologist scored b-1000 images and ADC maps for image quality measures. Sequences were compared using paired Wilcoxon tests. RESULTS: pTx with focused excitation showed significant improvements compared with standard DWI on b-1000 images at large-FOV for the absence of wrap and overall image quality (p ≤ 0.049); on b-1000 images at small-FOV for reduced distortion of prostate, absence of ghosting, absence of wrap, clarity of prostate capsule, clarity of peripheral/transition zone boundary, clarity of peri-urethral region, and overall image quality (p ≤ 0.004); and on ADC maps at small-FOV for reduced distortion of prostate, sharpness of prostate, clarity of prostatic capsule, clarity of peri-urethral region, and overall image quality (p = 0.002-0.036). When compared with standard large-FOV images, small-FOV images obtained using pTx with focused excitation showed no significant difference on the b-1000 images for any feature (p ≥ 0.175), while showing significant improvements on the ADC maps in terms of reduced distortion, absence of ghosting, and absence of wrap (p = 0.010-0.030). CONCLUSION: Zoomed DWI using 2-channel pTx reduced artifacts and improved image quality for 3T prostate DWI; benefit was most apparent for small-FOV images.

Comparison of MRI pulse sequences for prediction of size of hepatocellular carcinoma at explant evaluation.

OBJECTIVE: The purpose of this study was to retrospectively compare the size of hepatocellular carcinoma (HCC) on images obtained using different MRI pulse sequences with the tumor size determined at pathologic evaluation of liver explant specimens. MATERIALS AND METHODS: Ninety-two patients with HCC who underwent contrast-enhanced liver MRI within 90 days before liver transplant were included. A single pathologist measured the dominant HCC in each case. In different sessions, two abdominal radiologists (readers 1 and 2) aware only of the location of the dominant HCC independently measured lesion size on images obtained using the following sequences: T2-weighted imaging; b-500 diffusion-weighted imaging; and arterial, portal venous, and equilibrium phases of contrast enhancement. Size measurements on MR images were compared with explant measurements by use of Pearson correlation coefficients, paired t tests, and Bland-Altman plots. RESULTS: Correlation with pathologic findings was highest for reader 1 for portal venous (r = 0.890) and equilibrium (r = 0.828) phase images and for reader 2 for arterial, portal venous, and equilibrium phase images (r = 0.842-0.860). Absolute error relative to pathologic size was lowest for reader 1 using portal venous (4.3 mm) and for reader 2 using portal venous and arterial phase images (both 4.7 mm). Systematic error for both readers was lowest with portal venous and equilibrium phase images (reader 1, systematic under-measurement of 0.5 mm in both sequences; reader 2, systematic over-measurement of 0.1 mm with portal venous phase images and systematic under-measurement of 1.1 mm with equilibrium phase images). Sequences in which reader 1 made systematic over-measurements were diffusion-weighted images, arterial phase images, and T2-weighted images (by 3.5, 2.9, and 1.6 mm). Reader 2 made systematic over-measurements using arterial phase and T2-weighted images (by 1.5 and 0.4 mm). CONCLUSION: The data suggest the arterial phase may be suboptimal for measuring HCC at MRI. Portal venous phase acquisition warrants further investigation as a potential standard approach for such measurements.

Complex cystic renal masses: comparison of cyst complexity and Bosniak classification between 1.5 T and 3 T MRI.

PURPOSE: To retrospectively compare perceived complexity and Bosniak cyst classification of cystic renal lesions between 1.5 T and 3 T MRI. METHODS: 33 cystic renal lesions in 26 patients that underwent contrast-enhanced MRI at both 1.5 T and 3 T within a 12 month span were included. Two radiologists (R1, R2) independently assessed lesions, unaware of field strength, in terms of number of septations, septal thickening, mural thickening, presence of mural nodule, and Bosniak cyst category. Scores were compared between field strengths for each lesion. RESULTS: R1 observed increases in septal number, septal thickening, mural thickening, and presence of mural nodule at 3T in 8, 7, 4, and 2 lesions, and at 1.5 T in 3, 3, 2, and 0 lesions, respectively; R2 observed increases in septal number, septal thickening, mural thickening, and presence of mural nodule at 3T in 3, 4, 3, and 0 lesions, and at 1.5 T in 2, 0, 0, and 0 lesions, respectively. R1 provided higher Bosniak category at 3T in 9 cases and at 1.5 T in 4 cases; R2 provided higher Bosniak category at 3T in 4 cases and at 1.5 T in 0 cases. Higher scores at 3T than 1.5 T were associated with differences in advised clinical management in 7/9 cases for R1 and 4/4 cases for R2. CONCLUSION: There was an overall tendency for both readers to upgrade cyst complexity and Bosniak cyst category at 3T than 1.5 T, which impacted advised management. Thus, we suggest that serial MRI evaluation of cystic renal lesions be performed at constant field strength.