Accuracy of 68Ga-PSMA PET/CT for lymph node and bone primary staging in prostate cancer.

PURPOSE: The aim of this study is to assess the accuracy of the 68Ga-PSMA PET/CT for lymph nodes and bones in the primary stage of prostate cancer. METHODS: A total of 126 patients who were submitted to 68Ga-PSMA PET/CT from January 2016 to February 2019 for prostate cancer staging, detection of clinically significant lesions or active surveillance were included in this study. All studies were read by 2 experienced physicians (a nuclear physician and a radiologist). The reports were made in consensus and used by one of the authors to classify the exam in positive or negative. We evaluated presence of abnormal uptake in the prostate, lymph nodes, and bone. The reference standards were histopathological confirmation, confirmatory imaging exams and/or clinical follow-up showing lesion(s) regression after specific treatment, or typical osseous metastatic lesions and highly increased PSA levels. RESULTS: Measurement of diagnostic performance indicated a sensitivity, specificity and accuracy of 75%, 96.3%, and 90.8%, respectively, for lymph node involvement, and 90.9%, 50%, and 76.5%, respectively for metastatic bone lesions. CONCLUSION: This study showed high specificity and accuracy of 68Ga-PSMA PET/CT for lymph node and bone involvement in prostate cancer staging.

Which criteria can be used to predict benignity in solid renal lesions lower-equal to 2 cm?

PURPOSE: To evaluate magnetic resonance imaging (MRI) criteria of solid renal lesions lower-equal to 2 cm to differentiate benign and malignant tumors, using histopathology as gold standard. METHODS: Three radiologists independently evaluated objective and subjective MRI criteria of focal renal lesions. A total of 105 nodules of patients who had MRI and histopathological results in our institution were included. Subjective criteria evaluated were signal on T2-weighted imaging, presence of microscopic and macroscopic fat, hemosiderin, hemorrhage, central scar, segmented inversion enhancement and enhancement type; objective criteria were gender, ADC value, heterogeneity on T2-weighted imaging and proportion of enhancement in late post-contrast phases. Finally, the readers classified the lesions in probably benign or malignant. Interobserver agreement was evaluated by the Gwet method, and the quantitative variables by intraclass correlation coefficients. To adjust the predictive model, the logistic regression model was used considering the benignity variable as outcome. RESULTS: A total of 26 nodules (24.5%) were benign and 79 (75.2%) were malignant, with size ranging from 7 to 20 mm (median: 14 mm). The most frequent subtype was papillary renal cell carcinoma (RCC) (35.2%), followed by clear-cell RCC (24.8%) and oncocytoma (12.4%). The univariate and multivariate analysis showed, among all categories evaluated, that microscopic fat (p: 0.072), intermediate (p: 0.004) and hyper-enhancement (p: 0.031) and female sex (p: 0.0047) had the best outcome for benignity, within odds ratios of 4.29, 5.75, 4.07 and 2.86, respectively. CONCLUSION: In small solid renal lesions lower-equal to 2 cm, microscopic fat, moderate and hyper-enhancement and female sex were associated with benignity.

Interobserver agreement of PI-RADS v. 2 lexicon among radiologists with different levels of experience.

BACKGROUND: Evaluation of interobserver agreement of the PI-RADS v2 lexicon is important to validate the uniformity of this widely used classification. PURPOSE: To determine the interobserver agreement of PI-RADS v2 lexicon among eight radiologists with varying levels of experience. STUDY TYPE: Retrospective. POPULATION: In all, 160 consecutively imaged men with confirmatory targeted biopsy. FIELD STRENGTH/SEQUENCE: 3T scanner without an endorectal coil. T2 -weighted imaging (T2 w), diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) map and dynamic contrast-enhanced sequence were performed. ASSESSMENT: Eight radiologists (two highly experienced, two moderately experienced, and four less experienced) independently read 130 lesions in the peripheral zone (PZ) and 30 lesions in the transition zone (TZ), blinded to clinical MRI indication and biopsy results. The features described in PI-RADS v2 for TZ and PZ lesions were evaluated. STATISTICAL TESTS: Conger's kappa, percentage of concordance, and first-order agreement coefficient (AC1) were used to evaluate interobserver agreement. RESULTS: From the features evaluated on PZ lesions, definite extraprostatic extension (EPE) / invasive behavior on T2 w had good agreement (AC1 = 0.80), and the others had fair agreement (AC1 = 0.32-0.40). From the features evaluated on TZ lesions, two had good agreement: definite EPE/invasive behavior (AC1 = 0.77) and moderate/marked hypointensity (AC1 = 0.67) on T2 w. Encapsulation and lenticular shape on T2 w, focal (not indistinct) on DWI and ADC map, and marked hypointensity on ADC map (AC1 = 0.45 to 0.60) had moderate agreement, whereas heterogeneous and circumscribed (not obscured margins) on T2 w, marked hyperintensity on high-b-value DWI, and the presence or not of early enhancement in the lesion/region of the lesion (AC1 = 0.30 to 0.38) had fair agreement. DATA CONCLUSION: Interobserver agreement in PI-RADS v2 lexicon ranges from fair to good among radiologists and improves with increasing experience. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:593-602.

Prostate magnetic resonance imaging technique.

Multiparametric magnetic resonance (MR) imaging of the prostate is an excellent tool to detect clinically significant prostate cancer, and it has widely been incorporated into clinical practice due to its excellent tissue contrast and image resolution. The aims of this article are to describe the prostate MR imaging technique for detection of clinically significant prostate cancer according to PI-RADS v2.1, as well as alternative sequences and basic aspects of patient preparation and MR imaging artifact avoidance.

Malignancy Rate, Histologic Grade, and Progression of Bosniak Category III and IV Complex Renal Cystic Lesions.

OBJECTIVE: The primary purpose of this study is to determine the malignancy rate, histologic grade, and initial stage of surgically treated complex renal cysts classified as Bosniak category III or IV. For nonsurgical lesions, a secondary objective was to evaluate lesion progression on follow-up examinations. MATERIALS AND METHODS: We searched our database for cystic lesions classified as Bosniak III or IV category on CT or MRI from January 2008 to April 2016. Surgically resected lesions, per category, were correlated with information on pathologic reports to obtain malignancy rates. For malignant lesions, histologic grade and initial stage were evaluated. Imaging follow-up of at least 2 years was used to evaluate progression of clinically followed lesions. RESULTS: We included 86 lesions in 85 patients in the final analysis. Of the 60 surgically resected lesions (70%), 46 (77%) were malignant and 14 (23%) were benign. Malignancy rates were 72% for Bosniak category III lesions and 86% for Bosniak category IV lesions. Most malignant cysts were early-stage (pT1) cysts with low histologic grades (89% of Bosniak III lesions and 91% of Bosniak IV lesions). Follow-up studies of the surgically resected lesions did not show local recurrence, metastasis, or lymph node enlargement. Among patients with lesions managed by watchful waiting (n = 26), all lesions remained unchanged in terms of size and complexity after at least 2-years of follow-up. CONCLUSION: Although high malignancy rates were observed for both Bosniak category III and IV lesions, our results suggest that such malignant cysts are usually early-stage tumors with a low histologic grade. Lesions that underwent follow-up remained unchanged on control examinations. These findings may indicate low aggressiveness of these lesions, supporting the idea that more conservative approaches may be used.

Characterization of adrenal lesions at chemical-shift MRI: a direct intraindividual comparison of in- and opposed-phase imaging at 1.5 T and 3 T.

OBJECTIVE. The purpose of this article is to perform an intraindividual comparison between 1.5 T and 3 T chemical-shift MRI in differentiating adrenal adenomas and nonadenomas, including comparison of quantitative thresholds. MATERIALS AND METHODS. In this retrospective study, 37 adrenal lesions in 36 patients (20 men and 16 women; mean [± SD] age, 66.7 ± 12.9 years; 27 benign adenomas in 27 patients; 10 nonadenomas in nine patients) imaged at 1.5 T and 3 T were identified. Two readers qualitatively assessed intralesional signal loss between in- and opposed-phase images. One reader placed ROIs on adrenal lesions, spleen, liver, and muscle. Quantitative measures of signal loss, such as signal intensity (SI) index, adrenal-to-spleen ratio, adrenal-to-liver ratio, and adrenal-to-muscle ratio, were calculated. Qualitative and quantitative measures between field strengths were assessed with McNemar test and ROC analysis, respectively. RESULTS. Accuracy in qualitative adenoma identification (86.5% [32/37] at 1.5 T and 81.1% [30/37] at 3 T for reader 1; 81.1% [30/37] at 1.5 T and 83.8% [31/37] at 3 T for reader 2; both p ≥ 0.180) was equivalent at both field strengths. AUCs were not statistically significantly different between field strengths for quantitative measures: AUCs at 1.5 T versus 3 T were 0.956 versus 0.915 for SI index, 0.963 versus 0.870 for adrenal-to-spleen ratio, 0.935 versus 0.852 for adrenal-to-liver ratio, and 0.948 versus 0.948 for adrenal-to-muscle ratio (all p > 0.11). The optimal threshold for SI index was lower at 3 T (> 7.4%) than at 1.5 T (> 21.6%) but had similar sensitivity (1.5 T, 92.6% [25/27]; 3 T, 88.9% [24/27]) and specificity (1.5 T, 90.0% [9/10]; 3 T, 90.0% [9/10]). CONCLUSION. Chemical-shift imaging has similar diagnostic efficacy for differentiating adrenal adenomas and nonadenomas at 1.5 T and 3 T. However, quantitative measures have different thresholds for this differentiation at 3 T; in particular, the commonly applied SI index is much lower at 3 T.

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.

Diffusion-weighted imaging of the prostate: Comparison of b1000 and b2000 image sets for index lesion detection.

PURPOSE: To compare tumor detection on acquired diffusion-weighted (DW) images and apparent diffusion coefficient (ADC) maps, obtained using b-values of 1000 s/mm(2) and 2000 s/mm(2) , using radical prostatectomy as the reference. MATERIALS AND METHODS: In all, 29 prostate cancer patients who underwent 3T magnetic resonance imaging (MRI) including DW imaging using b-values of 1000 s/mm(2) and 2000 s/mm(2) were included. Two radiologists independently evaluated four image sets during different sessions and recorded the location and diameter of the dominant lesion: DW images acquired using b-values of 1000 s/mm(2) and 2000 s/mm(2) and ADC maps calculated using maximal b-values of 1000 s/mm(2) and 2000 s/mm(2) . Findings were correlated with the location and diameter of the dominant lesion at prostatectomy. Tumor-to-PZ contrast was also calculated, unblinded to pathology. RESULTS: Both readers achieved significantly higher sensitivity for DW images obtained using a b-value of 2000 s/mm(2) than 1000 s/mm(2) (P < 0.001), although there was no difference in sensitivity between ADC maps calculated using the two b-values (P ≥ 0.309). Tumor-to-PZ contrast was higher for DW images using a b-value of 2000 s/mm(2) (P = 0.067), although it was not different between the two corresponding ADC maps (P = 0.544). For both readers, correlations with tumor diameters were higher for either ADC map (r = 0.59-0.73) than for either acquired DW image set (r = 0.03-0.57). CONCLUSION: Use of a b-value of 2000 s/mm(2) compared with a b-value of 1000 s/mm(2) resulted in improved tumor sensitivity and higher tumor-to-PZ contrast on the acquired DW images, although performance of the ADC maps corresponding with the two b-values was similar. Correlation with tumor size was greater for either ADC map than for either acquired DW image set.

3.0 T multiparametric prostate MRI using pelvic phased-array coil: utility for tumor detection prior to biopsy.

OBJECTIVE: To evaluate the role of multiparametric magnetic resonance imaging (MRI) performed in men without a biopsy-proven diagnosis of prostate cancer using follow-up biopsy as the reference standard. MATERIALS AND METHODS: Forty-two patients without biopsy-proven cancer and who underwent MRI were included. In all patients, MRI was performed at 3T using a pelvic phased-array coil and included T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging. Thirteen had undergone no previous biopsy, and 29 had undergone at least 1 previous negative biopsy. All patients underwent prostate biopsy following MRI. Two fellowship-trained radiologists in consensus reviewed all cases and categorized each lobe as positive or negative for tumor. These interpretations were correlated with findings on post-MRI biopsy. RESULTS: Follow-up biopsy was positive in 23 lobes in 15 patients (36% of study cohort). On a per-patient basis, MRI had a sensitivity of 100%, specificity of 74%, positive predictive value (PPV) of 68%, and negative predictive value (NPV) of 100%. On a per-lobe basis, MRI had a sensitivity of 65%, specificity of 84%, PPV of 60%, and NPV of 86%. There was a nearly significant association between Gleason score and tumor detection on MRI (P = 0.072). CONCLUSIONS: In our sample, MRI had 100% sensitivity in predicting the presence of tumor on subsequent biopsy on a per-patient basis, suggesting a possible role for MRI in selecting patients with an elevated prostatic specific antigen (PSA) to undergo prostate biopsy. However, MRI had weaker specificity for prediction of a subsequent positive biopsy, as well as weaker sensitivity for tumor on a per-lobe basis, indicating that in patients with a positive MRI result, tissue sampling remains necessary for confirmation of the diagnosis as well as for treatment planning.

Characterization of malignancy of adnexal lesions using ADC entropy: comparison with mean ADC and qualitative DWI assessment.

PURPOSE: To establish the utility of apparent diffusion coefficient (ADC) entropy in discrimination of benign and malignant adnexal lesions, using histopathology as the reference standard, via comparison of the diagnostic performance of ADC entropy with mean ADC and with visual assessments of adnexal lesions on conventional and diffusion-weighted sequences. MATERIALS AND METHODS: In all, 37 adult female patients with an ovarian mass that was resected between June 2006 and January 2011 were included. Volume-of-interest was drawn to incorporate all lesion voxels on every slice that included the mass on the ADC map, from which whole-lesion mean ADC and ADC entropy were calculated. Two independent radiologists also rated each lesion as benign or malignant based on visual assessment of all sequences. The Mann-Whitney test and logistic regression for correlated data were used to compare performance of mean ADC, ADC entropy, and the visual assessments. RESULTS: No statistically significant difference was observed in mean ADC between benign and malignant adnexal lesions (P = 0.768). ADC entropy was significantly higher in malignant than in benign lesions (P = 0.009). Accuracy was significantly greater for ADC entropy than for mean ADC (0.018). ADC entropy and visual assessment by the less-experienced reader showed similar accuracy (P ≥ 0.204). The more experienced reader's accuracy was significantly greater than that of all other assessments (P ≤ 0.039). CONCLUSION: ADC entropy showed significantly greater accuracy than the more traditional metric of mean ADC for distinguishing benign and malignant adnexal lesions. Although whole-lesion ADC entropy provides a straightforward and objective measurement, its potential benefit decreases with greater reader experience.

Effect of flip angle for optimization of image quality of gadoxetate disodium-enhanced biliary imaging at 1.5 T.

OBJECTIVE: The purpose of this study was to perform a qualitative and quantitative comparison of image quality of gadoxetate disodium-enhanced imaging of the biliary system acquired using different flip angles (FAs). MATERIALS AND METHODS: Thirty-two patients (21 men and 11 women; mean [± SD] age, 51 ± 16 years) who underwent gadoxetate disodium-enhanced 1.5-T MRI were included. A 3D fat-suppressed T1-weighted gradient-echo sequence was acquired during the hepatobiliary phase using FAs of 12°, 25°, and 40°. One radiologist, who was blinded to FA, measured signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of the biliary tree. Two other blinded radiologists assessed subjective biliary duct clarity, overall image quality, background signal suppression, and ghosting artifact from the biliary tree using a scale of 1 to 4. RESULTS: SNRs and CNRs of the common bile duct were significantly higher for FAs of 25° (227.5 ± 113.2 and 191.0 ± 102.2, respectively) and 40° (239.6 ± 118.7 and 201.7 ± 107.7, respectively) than for 12° (168.9 ± 73.9 and 126.7 ± 59.7, respectively; all p < 0.001). There were no significant differences in SNR or CNR between FAs of 25° and 40° (p ≥ 0.360). Clarity of first-, second-, and third-order intrahepatic ducts, background signal suppression, and overall image quality were significantly higher for both readers for FAs of 25° and 40° than for 12° (all p ≤ 0.031). None of these comparisons was significantly different for either reader between FAs 25° and 40° (all p ≥ 0.091), aside from improved depiction of third-order ducts at 40° for one reader (p = 0.030). Biliary ghosting artifact was significantly worse at 40° than at 12° for both readers (p ≤ 0.016). CONCLUSION: The use of an FA larger than the clinical standard of approximately 12° has the potential to improve the image quality of gadoxetate disodium-enhanced biliary imaging.

Histogram analysis of whole-lesion enhancement in differentiating clear cell from papillary subtype of renal cell cancer.

PURPOSE: To compare histogram analysis of voxel-based whole-lesion (WL) enhancement to qualitative assessment and region-of-interest (ROI)-based enhancement analysis in discriminating the renal cell cancer (RCC) subtype clear cell RCC (ccRCC) from papillary RCC (pRCC). MATERIALS AND METHODS: In this institutional review board-approved, HIPAA-compliant retrospective study, 73 patients underwent magnetic resonance (MR) imaging prior to surgery for RCC between January 2007 and January 2010. Three-dimensional fat-suppressed T1-weighted gradient-echo corticomedullary phase acquisitions, obtained before and after contrast agent administration, were transferred to a workstation at which automated registration followed by semiautomated segmentation of the RCC was performed. Percent enhancement was computed on a per-voxel basis: (SI(post) - SI(pre))/SI(pre) .100, where SI(pre) and SI(post) indicate signal intensity before and after contrast enhancement, respectively. The WL quantitative parameters of mean, median, and third quartile enhancement and histogram distribution parameters kurtosis and skewness were computed for each lesion. WL enhancement parameters were compared with ROI-based analysis and qualitative assessment with regards to diagnostic accuracy and interreader agreement in differentiating ccRCC from pRCC. RESULTS: There were 19 pRCCs and 55 ccRCCs at pathologic examination. ccRCC had significantly higher WL mean, median, and third quartile enhancement compared with pRCC and hade significantly lower kurtosis and skewness (all P < .001). Third quartile enhancement had the highest accuracy (94.6%; area under the curve, 0.980) in discriminating ccRCC from pRCC, which was significantly higher than the accuracy of qualitative assessment (86.0%; P = .04) but not significantly higher than that of ROI enhancement (89.2%; P = .52). WL enhancement parameters had higher interreader agreement (κ = 0.91-1.0) compared with ROI enhancement or qualitative assessment (κ = 0.83 and 0.7, respectively) in discriminating ccRCC from pRCC. CONCLUSION: WL enhancement histogram analysis is feasible and can potentially be used to differentiate ccRCC from pRCC with high accuracy. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111281/-/DC1.

The effect of liver iron deposition on hepatic apparent diffusion coefficient values in cirrhosis.

OBJECTIVE: The purpose of this study was to assess the effect of hepatic iron deposition on apparent diffusion coefficient (ADC) values measured with single-shot echo-planar imaging (EPI) diffusion-weighted MRI (DWI) in patients with liver cirrhosis and in vitro. MATERIALS AND METHODS: Fifty-two patients with liver cirrhosis who underwent breath-hold single-shot EPI DWI at 1.5 T before liver transplantation were retrospectively assessed. Estimated signal-to-noise ratio (SNRest) and ADC were measured in the right hepatic lobe (for b values of 50 and 500 s/mm2). SNRest and ADC were compared between patients stratified by pathologic iron grade using the Mann-Whitney test. Hepatic ADC values were correlated to T2* values using the Spearman correlation test in a subset of patients. In addition, a phantom consisting of solutions of varying iron concentrations was imaged with single-shot EPI DWI and T2* imaging, and iron concentration was correlated with ADC and T2*. RESULTS: In phantoms, there was a decrease in ADC and T2* with increasing iron concentration (r=-0.95 and -0.92, respectively; p<0.05). Patients with hepatic siderosis had significantly lower SNRest and ADC compared with patients without siderosis (p<0.0001). SNRest at b=50 s/mm2 and b=500 s/mm2 and ADC had a significant negative correlation with pathologic iron grade (r=-0.67 to 0.77, p<0.0001). There was a significant correlation between liver T2* and ADC (r=0.83, p<0.0001). CONCLUSION: Hepatic siderosis lowers liver ADC and should be taken into account when using ADC for diagnosing liver cirrhosis.

Prostate cancer: multiparametric MRI for index lesion localization--a multiple-reader study.

OBJECTIVE: The purpose of this study was to evaluate the utility of multiparametric MRI in localization of the index lesion of prostate cancer. MATERIALS AND METHODS: Fifty-one patients who underwent 3-T MRI of the prostate with a pelvic phased-array coil that included T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences before prostatectomy were included. Six radiologists assessed all images to identify the lesion most suspicious of being the index lesion, which was localized to one of 18 regions. A uropathologist using the same 18-region scheme reviewed the prostatectomy slides to localize the index lesion. MRI performance was assessed by requiring either an exact match or an approximate match (discrepancy of up to one region) between the MRI and pathologic findings in terms of assigned region. RESULTS: The pathologist identified an index lesion in 49 of 51 patients. In exact-match analysis, the average sensitivity was 60.2% (range, 51.0-63.3%), and the average positive predictive value (PPV) was 65.3% (range, 61.2-69.4%). In approximate-match analysis, the average sensitivity was 75.9% (range, 65.3-69.6%), and the average PPV was 82.6% (range, 79.2-91.4%). The sensitivity was higher for index lesions with a Gleason score greater than 6 in exact-match (74.8% vs 15.3%, p<0.001) and approximate-match (88.7% vs 36.1%, p=<0.001) analyses and for index lesions measuring at least 1 cm in approximate-match analysis (80.3% vs 58.3%, p=0.016). In exact-match analysis, 30.0%, 44.9%, and 79.1% of abnormalities found with one, two, and three MRI parameters represented the index lesion (p<0.001). CONCLUSION: The sensitivity and PPV of multiparametric MRI for index lesion localization were moderate, although they improved in the setting of more aggressive pathologic features and a greater number of abnormal MRI parameters, respectively.

Comparison of CT-based methodologies for detection of growth of solid renal masses on active surveillance.

OBJECTIVE: The purpose of this study is to retrospectively compare 1D, 2D, and 3D measurements on CT for detection of growth of solid renal masses on active surveillance. MATERIALS AND METHODS: Forty solid renal masses measuring at least 1 cm in patients who underwent two CT studies at least 3 months apart were included. Two radiologists independently assessed the studies for interval growth using gestalt visual assessment and 1D, 2D, and 3D measurements. Prospective reports were also evaluated for indications of growth. The summation-of-areas technique was used to calculate volumes of lesions, which served as reference standard in determination of growth. Logistic regression analysis for correlated data was used to compare accuracy of methodologies for detection of lesion growth. Interreader agreement was assessed using kappa coefficients and intraclass correlation coefficients. RESULTS: The accuracy of gestalt visual, 1D, 2D, and 3D assessments for detection of interval growth was 72.5%, 70.0%, 82.5%, and 85% for reader 1 and 77.5%, 70.0%, 90.0%, and 95.0% for reader 2. These differences were significant or nearly significant (p = 0.003-0.054) for the greater accuracy of 2D or 3D measurements than for 1D measurements for reader 1 as well as the greater accuracy of 2D measurements than 1D measurements and 3D measurements than gestalt visual assessment or 1D measurements for reader 2. The accuracy of prospective reports for detection of growth was 65.0%. Reader agreement was fair for gestalt visual assessment (κ = 0.31) and nearly perfect for 1D, 2D, and 3D measurements (intraclass correlation coefficient = 0.97-0.99). CONCLUSION: Our results show that 2D or 3D measurements may be preferable to 1D measurements on CT in assessment for growth of solid renal masses on active surveillance.

Prevalence, characteristics, and fate of intrahepatic nontumorous arterioportal shunts on MRI in patients with hepatic steatosis.

OBJECTIVE: To assess the frequency, characteristics, and fate of arterioportal shunts in patients with hepatic steatosis and to compare this to the frequency in patients without liver disease. METHODS: Eighty-four patients with hepatic steatosis but no other known liver disease and who underwent 2 abdominal magnetic resonance imaging (MRI) examinations at least 1 year apart formed one study cohort. Eighty-four subjects without steatosis or other known liver disease and who also underwent 2 MRI examinations at least 1 year apart formed a control group. Two radiologists evaluated the initial study for the presence and characteristics of arterial enhancing foci not visible on other sequences and assessed the fate of these foci on the follow-up study. RESULTS: Of the patients with steatosis, 36.9% (95% confidence interval [CI], 26.6%-48.1%) demonstrated a total of 108 arterial enhancing foci, compared with 20 arterial enhancing foci in 13.1% of controls (95% CI, 6.7%-22.2%). Both the number of subjects with at least one arterial enhancing focus and the mean number per subject were significantly greater in the steatosis cohort (P < 0.001). The arterial enhancing foci were generally small and peripheral in location in both cohorts. On follow-up examination, all lesions disappeared, decreased in size, were stable, or increased slightly in size while remaining inconspicuous on other sequences. CONCLUSION: Findings consistent with arterioportal shunts were observed at an unexpectedly high frequency in the control group but at a significantly greater frequency in the steatosis group. All foci exhibited benign behavior on long-term follow-up. Future studies may assess for clinical implications of this finding in patients with hepatic steatosis.

Bladder cancer: utility of MRI in detection of occult muscle-invasive disease.

BACKGROUND: The presence of muscularis propria invasion by bladder cancer is a key factor in prognosis and treatment decisions, although may be missed by biopsy due to sampling error. MRI has shown potential for detection of muscle invasion but has not specifically been evaluated for this purpose in the setting of bladder cancer patients without evidence of muscle invasion on initial biopsy. PURPOSE: To evaluate the role of MRI in detection of muscularis propria invasion by bladder cancer following a pathologic diagnosis of non-invasive tumor. MATERIAL AND METHODS: This retrospective study included 23 patients who underwent pelvic MRI following a pathologic diagnosis of bladder cancer without muscularis propria invasion and in whom additional histologic evaluation was performed following MRI. Two radiologists in consensus reviewed T2-weighted images to identify those cases suspicious for muscle invasion on MRI. The radiologists identified whether cases suspicious for invasion demonstrated disruption of the T2-hypointense muscularis layer of the bladder wall, peri-vesical fat stranding, and peri-vesical soft tissue nodularity. Findings were compared with pathologic results obtained after MRI. RESULTS: Suspicion was raised for muscle invasion in eight of 23 cases, four of which exhibited invasion on follow-up pathology. No case without suspicion on MRI exhibited invasion on follow-up pathology. Therefore, sensitivity and specificity were 100% and 79%, respectively. Among individual findings, muscularis disruption on T2WI exhibited sensitivity of 100% and specificity of 79%, peri-vesical fat stranding exhibited sensitivity and specificity of 50% and 84%, and peri-vesical soft tissue nodularity exhibited sensitivity and specificity of 25% and 100%. CONCLUSION: MRI demonstrated high sensitivity for detection of muscle invasion in cases of bladder cancer without invasion on initial histologic assessment. Muscularis disruption on T2WI appeared to exhibit a better combination of sensitivity and specificity than did peri-vesical changes.

Prostate cancer: feasibility and preliminary experience of a diffusional kurtosis model for detection and assessment of aggressiveness of peripheral zone cancer.

PURPOSE: To assess the feasibility of diffusional kurtosis (DK) imaging for distinguishing benign from malignant regions, as well as low- from high-grade malignant regions, within the peripheral zone (PZ) of the prostate in comparison with standard diffusion-weighted (DW) imaging. MATERIALS AND METHODS: The institutional review board approved this retrospective HIPAA-compliant study and waived informed consent. Forty-seven patients with prostate cancer underwent 3-T magnetic resonance imaging by using a pelvic phased-array coil and DW imaging (maximum b value, 2000 sec/mm2). Parametric maps were obtained for apparent diffusion coefficient (ADC); the metric DK (K), which represents non-Gaussian diffusion behavior; and corrected diffusion (D) that accounts for this non-Gaussianity. Two radiologists reviewed these maps and measured ADC, D, and K in sextants positive for cancer at biopsy. Data were analyzed by using mixed-model analysis of variance and receiver operating characteristic curves. RESULTS: Seventy sextants exhibited a Gleason score of 6; 51 exhibited a Gleason score of 7 or 8. K was significantly greater in cancerous sextants than in benign PZ (0.96±0.24 vs 0.57±0.07, P<.001), as well as in cancerous sextants with higher rather than lower Gleason score (1.05±0.26 vs 0.89±0.20, P<.001). K showed significantly greater sensitivity for differentiating cancerous sextants from benign PZ than ADC or D (93.3% vs 78.5% and 83.5%, respectively; P<.001), with equal specificity (95.7%, P>.99). K exhibited significantly greater sensitivity for differentiating sextants with low- and high-grade cancer than ADC or D (68.6% vs 51.0% and 49.0%, respectively; P≤.004) but with decreased specificity (70.0% vs 81.4% and 82.9%, respectively; P≤.023). K had significantly greater area under the curve for differentiating sextants with low- and high-grade cancer than ADC (0.70 vs 0.62, P=.010). Relative contrast between cancerous sextants and benign PZ was significantly greater for D or K than ADC (0.25±0.14 and 0.24±0.13, respectively, vs 0.18±0.10; P<.001). CONCLUSION: Preliminary findings suggest increased value for DK imaging compared with standard DW imaging in prostate cancer assessment.

High-grade bladder cancer: association of the apparent diffusion coefficient with metastatic disease: preliminary results.

PURPOSE: To assess the utility of apparent diffusion coefficient (ADC) values obtained from diffusion-weighted imaging (DWI) in distinguishing high-grade bladder cancer with and without metastatic disease. MATERIALS AND METHODS: Seventeen patients with histologically confirmed high-grade bladder cancer who underwent pelvic magnetic resonance imaging (MRI) at 1.5T including DWI using b-values of 0, 400, and 800 sec/mm(2) were assessed. Histologic findings and follow-up imaging were used to establish the reference standard in terms of metastatic disease. Two radiologists independently recorded ADC of all lesions following a training session, with their results averaged. Mann-Whitney U-test, receiver operating characteristic (ROC) curve analysis and intraclass correlation coefficient (ICC) were used for data analysis. RESULTS: Metastatic disease was characterized as present or absent in eight and nine patients, respectively. ADC was significantly lower among cases with metastatic disease than among cases without metastatic disease, both within the entire cohort (1.07 ± 0.18 × 10(-3) mm(2)/s vs. 1.45 ± 0.22 × 10(-3) mm(2)/s; P = 0.002) and within the subset of patients with muscle-invasive tumor (1.06 ± 0.19 × 10(-3) mm(2)/s vs. 1.45 ± 0.23 × 10(-3) mm(2)/s; P = 0.017). Area under the ROC curve for identifying metastatic disease using ADC was 0.944, with optimal threshold of 1.21 × 10(-3) mm(2)/s, which was associated with a sensitivity of 87.5%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 90.0%. Interreader agreement for ADC was excellent (ICC = 0.91). CONCLUSION: In this preliminary study, ADC was significantly different between cases of high-grade urothelial carcinoma of the bladder with and without metastatic disease. These results may have value in assessing the metastatic potential of patients with localized high-grade tumors of the bladder.