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ABSTRACT: We compared individual computed tomography (CT) and MRI findings in differentiating acute from chronic cholecystitis. Thirty-seven patients undergoing both studies before cholecystectomy were included. Two radiologists (R1/R2) independently assessed all cases. For detecting acute cholecystitis, MRI showed better sensitivity (R1) using gallbladder wall thickening, accuracy (R1) and sensitivity (R1) using gallstones, sensitivity (R1 and R2) and accuracy (R2) using gallbladder wall hyperemia, accuracy (R1 and R2) using gallbladder wall defect, and accuracy (R2) using adjacent liver hyperemia (P=.004-.063). MRI also showed better specificity (R2) using pericholecystic fat stranding (P=.016). Overall, several findings showed better sensitivity and/or accuracy for acute cholecystitis on MRI than CT.
Clinical imaging 03/2013; · 0.73 Impact Factor
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ABSTRACT: OBJECTIVE: To determine whether suspicion for tumor on prostate MRI incorporating T2-weighted imaging (T2-WI) and diffusion-weighted imaging (DWI) predicts more adverse pathology on radical prostatectomy (RP). METHODS: From 2007 to 2009, 154 patients underwent 1.5 Tesla pelvic-phased-array magnetic resonance imaging (MRI) of the prostate that included T2-WI and DWI before RP. MRI examinations were retrospectively reviewed and grouped by degree of suspicion for tumor: no suspicion for tumor (NST, n = 15), equivocal suspicion for tumor (EST, n = 60), or strong suspicion for tumor (SST, n = 79). The NST/EST groups were combined and compared to the SST group. Preoperative variables were used to assemble a multivariate model. Outcomes reflective of adverse pathology included primary Gleason grade ≥4, pathologic stage ≥T3 (≥pT3), and tumor upgrading. Subgroup analysis was performed for patients meeting eligibility criteria for active surveillance (n = 55). For this analysis, the NST group was compared to the EST/SST groups. RESULTS: SST status was associated with adverse preoperative risk factors for aggressive disease. Univariate analysis demonstrated significant association between SST and primary Gleason ≥4 pathology and stage ≥pT3 (P <.05). On multivariate analysis, SST was independently predictive of primary Gleason ≥4 pathology (odds ratio [OR] 6.14, 95% confidence interval [CI] 1.97-19.2) and Gleason upgrading (OR 2.47, 95% CI 1.01-6.02). Among patients eligible for active surveillance, those in the NST group had decreased likelihood of Gleason ≥7 disease or stage ≥pT3 compared to the EST/SST groups (7.7% vs 47.6%, P = .01). CONCLUSION: Increased tumor suspicion on T2-WI/DWI MRI is indicative of adverse pathology on RP. These findings suggest a role for MRI in pretreatment risk assessment.
Urology 02/2013; · 2.43 Impact Factor
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ABSTRACT: 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. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
Journal of Magnetic Resonance Imaging 01/2013; · 2.70 Impact Factor
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ABSTRACT: PURPOSE: To improve robustness to patient motion of "fresh blood imaging" (FBI) for lower extremity noncontrast MR angiography. METHODS: In FBI, two sets of three-dimensional fast spin echo images are acquired at different cardiac phases and subtracted to generate bright-blood angiograms. Routinely performed with a single coronal slab and sequential acquisition of systolic and diastolic data, FBI is prone to subtraction errors due to patient motion. In this preliminary feasibility study, FBI was implemented with two sagittal imaging slabs, and the systolic and diastolic acquisitions were interleaved to minimize sensitivity to motion. The proposed technique was evaluated in volunteers and patients. RESULTS: In 10 volunteers, imaged while performing controlled movements, interleaved FBI demonstrated better tolerance to subject motion than sequential FBI. In one patient with peripheral arterial disease, interleaved FBI offered better depiction of collateral flow by reducing sensitivity to inadvertent motion. CONCLUSIONS: FBI with interleaved acquisition of diastolic and systolic data in two sagittal imaging slabs offers improved tolerance to patient motion. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
Magnetic Resonance in Medicine 01/2013; · 2.96 Impact Factor
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ABSTRACT: 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).
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.
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).
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.
American Journal of Roentgenology 01/2013; 200(1):90-6. · 2.78 Impact Factor
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ABSTRACT: PURPOSE: To assess the utility of diffusion-weighted imaging (DWI) findings as an indirect marker of side-specific risk of extracapsular extension (ECE) of prostate cancer. MATERIALS AND METHODS: Fifty-one patients underwent 3T magnetic resonance imaging (MRI) before prostatectomy. Radiologists 1 and 2 (4 and 1 years experience) assessed each side for ECE using T2-weighted imaging (T2WI) and evaluated apparent diffusion coefficient (ADC) maps for the presence of apparent tumor in each lobe and to measure peripheral zone ADC. A uropathologist measured the extent of any ECE. RESULTS: In all, 28/102 lobes had ECE, of which 12 measured ≤1 mm, 11 measured >1 mm and ≤2 mm, and five measured >2 mm. Side-specific accuracies for detection of ECE for readers 1 and 2 were respectively: T2WI 68.6% and 74.5%; presence of apparent tumor on ADC map 66.7% and 60.8%; ADC value 75.5% and 69.6%. For ECE >2 mm, both readers achieved 100% sensitivity based on apparent tumor on ADC map or ADC values and 80% sensitivity using T2WI. For detection of ECE ≤2 mm, sensitivity for all combinations of the three methods and two readers ranged from 58.3%-81.8%, aside from assessment for ECE using T2WI by the less experienced reader, which exhibited sensitivity of 17.4%. Interreader agreement for the presence of ECE was 0.18 using T2WI, 0.37 using apparent tumor on ADC map, and 0.60 using ADC values. CONCLUSION: Compared with T2WI, DWI had comparable accuracy for side-specific assessment of ECE, greater sensitivity for ECE <2 mm for the less-experienced radiologist, and greater interreader agreement. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.
Journal of Magnetic Resonance Imaging 12/2012; · 2.70 Impact Factor
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Hersh Chandarana, Andrew B Rosenkrantz,
Thais C Mussi,
Sooah Kim,
Afshan A Ahmad,
Sean D Raj,
John McMenamy,
Jonathan Melamed,
James S Babb,
Berthold Kiefer,
Atilla P Kiraly
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ABSTRACT: 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. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111281/-/DC1.
Radiology 12/2012; 265(3):790-8. · 5.73 Impact Factor
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ABSTRACT: 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. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.
Journal of Magnetic Resonance Imaging 11/2012; · 2.70 Impact Factor
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ABSTRACT: OBJECTIVE: The objectives of this study were to develop a new method for free-breathing contrast-enhanced multiphase liver magnetic resonance imaging (MRI) using a combination of compressed sensing, parallel imaging, and radial k-space sampling and to demonstrate the feasibility of this method by performing image quality comparison with breath-hold cartesian T1-weighted (conventional) postcontrast acquisitions in healthy participants. MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant prospective study received approval from the institutional review board. Eight participants underwent 3 separate contrast-enhanced fat-saturated T1-weighted gradient-echo MRI examinations with matching imaging parameters: conventional breath-hold examination with cartesian k-space sampling volumetric interpolate breath hold examination (BH-VIBE) and free-breathing acquisitions with interleaved angle-bisection and continuous golden-angle radial sampling schemes. Interleaved angle-bisection and golden-angle data from each 100 consecutive spokes were reconstructed using a combination of compressed sensing and parallel imaging (interleaved-angle radial sparse parallel [IARASP] and golden-angle radial sparse parallel [GRASP]) to generate multiple postcontrast phases.Arterial- and venous-phase BH-VIBE, IARASP, and GRASP reconstructions were evaluated by 2 radiologists in a blinded fashion. The readers independently assessed quality of enhancement (QE), overall image quality (IQ), and other parameters of image quality on a 5-point scale, with the highest score indicating the most desirable examination. Mixed model analysis of variance was used to compare each measure of image quality. RESULTS: Images of BH-VIBE and GRASP had significantly higher QE and IQ values compared with IARASP for both phases (P < 0.05). The differences in QE between BH-VIBE and GRASP for the arterial and venous phases were not significant (P > 0.05). Although GRASP had lower IQ score compared with BH-VIBE for the arterial (3.9 vs 4.8; P < 0.0001) and venous (4.2 vs 4.8; P = 0.005) phases, GRASP received IQ scores of 3 or more in all participants, which was consistent with acceptable or better diagnostic image quality. CONCLUSION: Contrast-enhanced multiphase liver MRI of diagnostic quality can be performed during free breathing using a combination of compressed sensing, parallel imaging, and golden-angle radial sampling.
Investigative radiology 11/2012; · 4.85 Impact Factor
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ABSTRACT: OBJECTIVE: The purpose of this study was to monitor iron clearance from the liver by means of T2 and T2* mapping after administration of an ultrasmall superparamagnetic iron oxide (USPIO) agent. MATERIALS AND METHODS: The study was performed using ferumoxytol (Feraheme), a USPIO agent that has been approved by the US Food and Drug Administration for the treatment of iron deficiency anemia in adult patients with chronic kidney disease. Six healthy human participants without anemia or preexisting iron overload were prospectively included. The cohort comprised 4 men and 2 postmenopausal women, aged 22 to 57 years. T2 and T2* mapping of the liver were performed at 1.5 T using multiple spin echo and multiple gradient echo sequences, respectively. After baseline imaging, ferumoxytol was injected intravenously at a dose of 5 mg Fe/kg body weight. Imaging was repeated at 3 days, 1 month, and every 2 months thereafter for up to 11 months or until liver T2* had recovered to 24 milliseconds, the threshold used to define iron deposition. For each examination, maps of the relaxation rates R2 (= 1/T2) and R2* (= 1/T2*) were generated by fitting the signal intensity data as a function of echo time to a monoexponential decay. RESULTS: No adverse reactions to ferumoxytol injection occurred. The magnetic resonance (MR) responses to ferumoxytol varied widely among the participants. Liver R2* increased from a mean value of 35.6 s (range, 28.7-40.9 s) at baseline to a mean value of 241 s (range, 161-417 s) 3 days after administration. Liver R2 increased from 19.4 s (range, 16.6-23.8 s) at baseline to 45.3 s (range, 34.4-58.5 s) at 3 days. There was also a large variation in iron clearance times. In 1 participant, MR relaxation rates had recovered to baseline by 3 months, whereas, in 3 participants, liver R2* remained elevated at 11 months (R2* > 55 s, ie, T2* < 18 milliseconds). In these 3 participants, liver R2 also remained marginally higher at 11 months than corresponding baseline values. CONCLUSIONS: Iron deposition in the liver after a 5 mg Fe/kg dose of ferumoxytol may alter signal contrast on MR images for several months after administration. This is an important consideration in the use of USPIO agents for diagnostic purposes.
Investigative radiology 10/2012; · 4.85 Impact Factor
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Andrew B Rosenkrantz,
Fang-Ming Deng,
Sooah Kim,
Ruth P Lim,
Nicole Hindman,
Thais C Mussi,
Bradley Spieler,
Jason Oaks,
James S Babb,
Jonathan Melamed,
Samir S Taneja
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ABSTRACT: The purpose of this study was to evaluate the utility of multiparametric MRI in localization of the index lesion of prostate cancer.
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.
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).
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.
American Journal of Roentgenology 10/2012; 199(4):830-7. · 2.78 Impact Factor
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ABSTRACT: OBJECTIVE: To evaluate the prognostic implications of the MRI appearance and pathological features of papillary renal cell carcinoma (pRCC). METHODS: A total of 128 pRCC in 115 patients who underwent preoperative MRI were characterised in terms of pathological type (type 1 vs. type 2), MRI appearance (focal vs. infiltrative) and additional MRI features. Patients were classified on the basis of the presence or absence of metastatic disease. RESULTS: There were 65 focal type 1, 54 focal type 2 and 9 infiltrative pRCC. All infiltrative pRCC were of histopathological type 2. Renal vein thrombus was present in 89 % of infiltrative pRCC and no cases of focal pRCC. Metastatic disease was observed in 3.7 % of focal type 1, 7.5 % of focal type 2 and 75.0 % of infiltrative type 2 pRCC. Infiltrative MRI appearance was a significant predictor of metastatic disease, independent of pathological type, size and T stage (P ≤ 0.020). Among focal pRCC on MRI, pathological type 2 was not a significant predictor of metastatic disease (P = 0.648). No combination of features achieved significantly greater accuracy for predicting metastatic disease than renal vein thrombus alone (P > 0.5). CONCLUSION: Infiltrative MRI appearance and renal vein thrombus identify a subset of pathological type 2 pRCC at a significantly increased risk of metastatic disease. KEY POINTS : • Magnetic resonance imaging (MRI) offers new preoperative insights into renal cell carcinoma (RCC). • Certain MRI features are associated with metastatic papillary RCC. • Metastases seem more common given an infiltrative appearance and renal vein thrombus.
European Radiology 08/2012; · 3.22 Impact Factor
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The Journal of urology 08/2012; 188(4):1072-3. · 4.02 Impact Factor
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ABSTRACT: 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.
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.
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).
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.
American Journal of Roentgenology 08/2012; 199(2):373-8. · 2.78 Impact Factor
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ABSTRACT: OBJECTIVES: The objective was to perform ex vivo evaluation of non-Gaussian diffusion kurtosis imaging (DKI) for assessment of hepatocellular carcinoma (HCC), including presence of treatment-related necrosis, using fresh liver explants. METHODS: Twelve liver explants underwent 1.5-T magnetic resonance imaging using a DKI sequence with maximal b-value of 2000 s/mm(2). A standard monoexponential fit was used to calculate apparent diffusion coefficient (ADC), and a non-Gaussian kurtosis fit was used to calculate K, a measure of excess kurtosis of diffusion, and D, a corrected diffusion coefficient accounting for this non-Gaussian behavior. The mean value of these parameters was measured for 16 HCCs based upon histologic findings. For each metric, HCC-to-liver contrast was calculated, and coefficient of variation (CV) was computed for voxels within the lesion as an indicator of heterogeneity. A single hepatopathologist determined HCC necrosis and cellularity. RESULTS: The 16 HCCs demonstrated intermediate-to-substantial excess diffusional kurtosis, and mean corrected diffusion coefficient D was 23% greater than mean ADC (P=.002). HCC-to-liver contrast and CV of HCC were greater for K than ADC or D, although these differences were significant only for CV of HCCs (P≤.046). ADC, D and K all showed significant differences between non-, partially and completely necrotic HCCs (P≤.004). Among seven nonnecrotic HCCs, cellularity showed a strong inverse correlation with ADC (r=-0.80), a weaker inverse correlation with D (-0.24) and a direct correlation with K (r=0.48). CONCLUSIONS: We observed non-Gaussian diffusion behavior for HCCs ex vivo; this DKI model may have added value in HCC characterization in comparison with a standard monoexponential model of diffusion-weighted imaging.
Magnetic Resonance Imaging 07/2012; · 1.99 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Journal of computer assisted tomography 07/2012; 36(4):375-80. · 1.38 Impact Factor
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ABSTRACT: The objective of our study was to retrospectively compare the MRI features of retroperitoneal fibrosis (RPF) and lymphoma presenting as confluent retroperitoneal soft tissue.
MRI studies of 31 patients (18 men, 13 women; mean age, 58.4 ± 15.8 [SD] years; 22 with RPF and nine with lymphoma) were evaluated. Two radiologists independently and in consensus evaluated all cases for an array of subjective imaging features. A third radiologist measured the size (i.e., the greatest dimension in the transverse plane) and apparent diffusion coefficient (ADC) value of the tissue. Features of RPF and lymphoma were compared using the Fisher exact test, Mann-Whitney test, and receiver operating characteristic (ROC) curve analysis. Interreader concordance was also calculated.
The mean age of patients with lymphoma was significantly greater than that in cases of RPF (72.4 ± 13.3 [SD] vs 52.7 ± 13.2 years, respectively; p = 0.003). The MRI features significantly more common in patients with RPF were pelvic extension (p = 0.004) and medial ureteral bowing (p < 0.001). The MRI features significantly more common in cases of lymphoma were predominantly suprarenal location, perirenal extension, anterior aortic displacement, heterogeneity, and the presence of additional nodes (p < 0.001-0.043). Size was significantly greater in patients with lymphoma than in those with RPF (mean ± SD, 33.9 ± 17.3 vs 11.0 ± 5.7 mm; p < 0.001) and had an area under the curve (AUC) of 0.960; a size larger than 15 mm had sensitivity of 100% and specificity of 86.4% for the diagnosis of lymphoma. The ADC was significantly lower in lymphoma than in RPF (mean ± SD, 0.92 ± 0.17 vs 1.40 ± 0.38 × 10(-3) mm(2)/s; p = 0.003) and had an AUC of 0.904. An ADC of 0.955 × 10(-3) mm(2)/s or less had sensitivity of 83.3% and specificity of 89.5% for the diagnosis of lymphoma. Interreader concordance for subjective features was very good to excellent (range, 80.6-100%).
MRI features may be helpful in distinguishing between RPF and lymphoma.
American Journal of Roentgenology 07/2012; 199(1):118-26. · 2.78 Impact Factor
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ABSTRACT: 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.
To evaluate the role of MRI in detection of muscularis propria invasion by bladder cancer following a pathologic diagnosis of non-invasive tumor.
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.
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%.
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.
Acta Radiologica 05/2012; 53(6):695-9. · 1.37 Impact Factor
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ABSTRACT: 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.
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.
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).
Preliminary findings suggest increased value for DK imaging compared with standard DW imaging in prostate cancer assessment.
Radiology 05/2012; 264(1):126-35. · 5.73 Impact Factor
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ABSTRACT: We identified histological differences between prostate cancer foci that are detected and missed using multiparametric magnetic resonance imaging.
A total of 49 patients who underwent multiparametric magnetic resonance imaging, including T2-weighted imaging, including diffusion weighted imaging and dynamic contrast enhanced imaging, before prostatectomy were enrolled in the study. One radiologist identified areas highly suspicious for tumor. One pathologist identified and categorized tumors in terms of size, Gleason score, solid tumor growth, intermixed benign glands, loose stroma, desmoplastic stroma and a high malignant epithelium-to-stroma ratio. Differences between detected and missed tumors were assessed using logistic regression analyses based on generalized estimating equations for correlated data.
All histological features showed significant differences between detected and missed tumors on multiparametric magnetic resonance imaging (p<0.0001). Independent predictors of detection on multivariate analysis were size (OR 5.38, p=0.0077), Gleason score (OR 5.12, p=0.0094) and solid growth (OR 17.83, p<0.0001). Size, Gleason score and loose stroma were significant predictors of identification with diffusion weighted imaging on univariate analysis (p≤0.0245), while Gleason score (OR 17.05, p=0.0212) and solid growth (OR 34.90, p=0.0103) were independent predictors of identification with diffusion weighted imaging on multivariate analysis. Identification with T2-weighted imaging was associated with size and Gleason score (p≤0.01876). Identification with dynamic contrast enhanced imaging was associated with intermixed benign epithelium, loose stroma and a high malignant epithelium-to-stroma ratio (p≤0.0499). No combination of features served as independent predictors on multivariate analysis for T2-weighted imaging or dynamic contrast enhanced imaging.
There are fundamental histological differences between detected and missed prostate tumors using magnetic resonance imaging. Insights into these differences may facilitate the prospective role of magnetic resonance imaging in counseling and treatment selection for patients with prostate cancer.
The Journal of urology 04/2012; 187(6):2032-8. · 4.02 Impact Factor
