Faculty Bibliography

BACKGROUND:Chemical-shift magnetic resonance imaging (MRI) has been known to successfully differentiate adenomas from metastases. However, there has been concern that metastasis from extra-adrenal primary malignancies which contain high lipid content such as clear cell renal cell carcinoma (RCC) could mimic adrenal adenomas. PURPOSE/OBJECTIVE:To evaluate the ability of MR to differentiate adrenal adenoma from metastasis using chemical-shift imaging and MR feature analysis in patients with clear cell RCC. MATERIAL AND METHODS/METHODS:This study was institutional review board-approved; informed consent was waived. Eleven patients with 13 metastases and 13 patients with 15 adrenal adenomas in patients with clear cell RCC for evaluation of an adrenal mass underwent MR. Signal intensity on in- and opposed-phases, signal intensity index (SII), size, T2 SI, cystic change, necrosis, and hemorrhage were evaluated. Statistical analyses included Student t-test and Fisher exact test. If available, precontrast CT attenuation of the adrenal adenomas was measured. SII was correlated with attenuation using Pearson correlation coefficient. RESULTS:Mean size of adenomas was smaller than that of metastases (P < 0.002). Mean SII of adenomas (45.0% ± 24.6) was significantly greater than that of metastases (6.6% ± 4.7; P < 0.001). With a threshold of 16.5% for SII, the sensitivity, specificity, and accuracy for adenomas were 80%, 100%, and 89.2%, respectively. All six lipid-rich adenomas were diagnosed as adrenal adenoma. Three of eight (37.5%) lipid-poor adenomas were misdiagnosed as metastases. While up to 53.8% (7/13) of the metastases demonstrated cystic change, necrosis, or hemorrhage, only one (6.7%) adenoma exhibited cystic change or necrosis (P < 0.05 for all). Precontrast attenuation and SII were significantly correlated: r = -0.810 (P < 0.001). CONCLUSION/CONCLUSIONS:In patients with clear cell RCC who underwent MR for adrenal masses, SII and MR features such as cystic change, necrosis, and hemorrhage were helpful in differentiating adenomas from metastases.

PURPOSE/OBJECTIVE:The aim of this study was to evaluate the safety and accuracy of a new portable ultrasonography-guided high-intensity focused ultrasound (USg-HIFU) system with a 3-dimensional (3D) electronic steering transducer, a simultaneous ablation and imaging module, real-time cavitation monitoring, and 3D image reconstruction algorithms. METHODS:To address the accuracy of the transducer, hydrophones in a water chamber were used to assess the generation of sonic fields. An animal study was also performed in five pigs by ablating in vivo thighs by single-point sonication (n=10) or volume sonication (n=10) and ex vivo kidneys by single-point sonication (n=10). Histological and statistical analyses were performed. RESULTS:In the hydrophone study, peak voltages were detected within 1.0 mm from the targets on the y- and z-axes and within 2.0-mm intervals along the x-axis (z-axis, direction of ultrasound propagation; y- and x-axes, perpendicular to the direction of ultrasound propagation). Twenty-nine of 30 HIFU sessions successfully created ablations at the target. The in vivo porcine thigh study showed only a small discrepancy (width, 0.5-1.1 mm; length, 3.0 mm) between the planning ultrasonograms and the pathological specimens. Inordinate thermal damage was not observed in the adjacent tissues or sonic pathways in the in vivo thigh and ex vivo kidney studies. CONCLUSION/CONCLUSIONS:Our study suggests that this new USg-HIFU system may be a safe and accurate technique for ablating soft tissues and encapsulated organs.

PURPOSE/OBJECTIVE:The aim of this study was to explore the usefulness of the resistive index (RI) on spectral Doppler ultrasonography (US) in the detection of renal cell carcinoma (RCC) in patients with end-stage renal disease (ESRD). METHODS:Seventeen ESRD patients with kidneys in which renal masses were suspected in routine US were subjected. They underwent computed tomography scans and additional Doppler US for the characterization of the detected lesions. All underwent radical nephrectomy with the suspicion of RCC. Fourteen patients finally were included. RI measurements were conducted in the region of the suspected renal mass and the background renal parenchyma. The intraclass correlation coefficient was used to assess the reproducibility of the RI measurement. A paired t-test was used to compare the RI values between the renal mass and the background renal parenchyma (P<0.05). RESULTS:The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma (0.41-0.65 vs. 0.75-0.89; P<0.001). The intrareader reproducibility proved to be excellent and good for the renal masses and the parenchyma, respectively (P<0.001). CONCLUSION/CONCLUSIONS:RI on spectral Doppler US is useful in detecting RCC in patients with ESRD. The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma.

PURPOSE/OBJECTIVE:To compare the association of intravoxel incoherent motion (IVIM)-derived parameters and apparent diffusion coefficient (ADC) with the histologic grade of hepatocellular carcinoma (HCC) and evaluate the relationship between IVIM-derived parameters and arterial enhancement degree. MATERIALS AND METHODS/METHODS:This retrospective study was institutional review board-approved, and informed consent was waived. Forty patients with 42 surgically confirmed HCCs underwent diffusion-weighted magnetic resonance (MR) imaging with eight b values (0-800 sec/mm(2)). ADC, diffusion coefficient (D), pseudodiffusion coefficient, and perfusion fraction (f) were calculated. Two radiologists determined the enhancement degree in consensus, as well as the percentage of arterial enhancement of HCC. The relationship between the parameters and histologic grade, as well as arterial enhancement, was assessed by using the Spearman or Pearson correlation test. Receiver operating characteristic (ROC) analysis of discrimination between low-grade (grades 1 and 2) and high-grade (grades 3 and 4) HCC was performed for D and ADC values. RESULTS:D and ADC values were both significantly correlated with histologic grade: r = -0.604 (P < .0001) and r = -0.448 (P = .002), respectively. D and ADC values were both significantly lower in high-grade HCC (D = [0.99 ± 0.13] × 10(-3)mm(2)/sec, ADC = [1.13 ± 0.14] × 10(-3)mm(2)/sec) than in low-grade HCC (D = [1.18 ± 0.16] × 10(-3)mm(2)/sec, ADC = [1.25 ± 0.17] × 10-(3)mm(2)/sec) (P < .0001 and P = .029, respectively). However, ROC analysis demonstrated a higher area under the ROC curve value for D than for ADC for differentiating high-grade HCC from low-grade HCC (0.838 vs 0.728; P = .026). The percentage of arterial enhancement was correlated with f (r = 0.621, P < .0001). CONCLUSION/CONCLUSIONS:IVIM-derived D values of HCC showed significantly better diagnostic performance than ADC values in differentiating high-grade HCC from low-grade HCC, and significant correlation was observed between f and the percentage of arterial enhancement.

A rubber tip disconnection of Arrow-Trerotola percutaneous thrombolytic device (PTD) may occur occasionally. We experienced 5 cases of a rubber tip disconnection among 453 mechanical thrombectomy sessions with the use of PTD. We present a report about these five cases and suggest possible causes for the occurrences.

OBJECTIVE:To assess the diagnostic value of shear wave elastography (SWE) for prostate cancer detection. MATERIALS AND METHODS/METHODS:In this retrospective study, 87 patients with the suspicion of prostate cancer (prostate-specific antigen > 4 ng/mL and abnormal digital rectal examination) underwent a protocol-based systematic 12-core biopsy followed by targeted biopsy at hypoechoic areas on grey-scale ultrasound. Prior to biopsy, SWE was performed by placing two circular 5 mm-sized regions of interest (ROIs) along the estimated biopsy tract in each sector and one ROI for hypoechoic lesions. SWE parameters, S (mean stiffness) and R (mean stiffness ratio), were calculated and compared regarding different histopathologic tissues and their accuracy for diagnosing prostate cancer was analyzed. SWE parameters were correlated with Gleason score and were compared between indolent (< 8) and aggressive (≥ 8) tissues in prostate cancer patients. RESULTS:Prostate cancer was detected in 7.5% of 1058 cores in 29.9% of 87 patients. Seven (43.8%) of 16 hypoechoic lesions were confirmed as prostate cancer. SWE parameters were significantly different among the histopathologic entities (p < 0.001). Prostate cancer was stiffer than benign tissues (p ≤ 0.003). Sensitivity, specificity and receiver operating characteristic curve area for diagnosing cancer were 43%, 80.8%, and 0.599, respectively, for a cutoff of S > 43.9 kPa and 60.8%, 66.4%, and 0.653, respectively, for R > 3. Both, S and R showed a significant correlation with Gleason score (r ≥ 0.296, p ≤ 0.008) and were significantly different between indolent and aggressive prostate cancer (p ≤ 0.006). CONCLUSION/CONCLUSIONS:Shear wave elastographic parameters are significantly different between prostate cancer and benign prostate tissue and correlate with Gleason score.

PURPOSE/OBJECTIVE:To retrospectively compare safety and effectiveness of embolic agents polyvinyl alcohol (PVA) particles versus n-butyl-2-cyanoacrylate (NBCA) for bronchial artery embolization (BAE) for control of hemoptysis. MATERIALS AND METHODS/METHODS:Institutional review board approved this retrospective study; informed consent was waived. From January 2005 to December 2008, 406 patients (242 men, 164 women; age range, 6-92 years) with major hemoptysis underwent BAE by using PVA particles (n = 293) or NBCA (n = 113). Technical and clinical success, complications, hemoptysis-free survival rates, and causes of recurrent hemoptysis were compared between PVA and NBCA groups. The differences in hemoptysis-free survival rates were assessed between subgroups stratified to underlying diseases. The predictive factor for recurrent hemoptysis was identified with Cox proportional hazard regression model. RESULTS:Technical success was achieved in 93.9% (275 of 293) and 96.5% (109 of 113) of patients for PVA and NBCA, respectively (P = .463); clinical success was achieved in 92.2% (270 of 293) and 96.5% (109 of 113) of patients for PVA and NBCA, respectively (P = .180). Overall and major complication rates were not statistically different (overall complication rates: 34.1% for PVA, 31.0% for NBCA; P = .56; major complication rates: 0.3% for PVA, 0% for NBCA; P > .999). The 1-, 3-, and 5-year hemoptysis-free survival rates were, respectively, 77%, 68%, and 66% for PVA and 88%, 85%, and 83% for NBCA (P = .01). Recanalization of previously embolized vessels was more frequent in PVA group (21.5%) than in NBCA group (1.8%; P < .001). NBCA group showed hemoptysis-free survival rates superior to PVA group in patients with bronchiectasis (P = .016). PVA (P = .050) and aspergilloma (P < .001) were predictive factors for recurrent hemoptysis. CONCLUSION/CONCLUSIONS:BAE with NBCA provided higher hemoptysis-free survival rates compared with PVA particles without increasing complication rates. This improvement was evident in patients with bronchiectasis and was caused by more durable embolic effect than PVA particles. SUPPLEMENTAL MATERIAL/BACKGROUND:http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130046/-/DC1.

PURPOSE/OBJECTIVE:To prospectively assess and compare the measurement variability of volume and mass for pure and part-solid ground-glass nodules (GGNs) with solid portions less than or equal to 5 mm by using a commercially available volumetric software program. MATERIALS AND METHODS/METHODS:This prospective study was approved by the institutional review board. Written informed consent was obtained. From November 2011 to June 2012, 73 patients (26 men and 47 women) with 94 GGNs (>5 mm and <20 mm; 72 pure and 22 part-solid GGNs) were prospectively enrolled and underwent two consecutive computed tomographic (CT) examinations. Both the volume and mass of GGNs were measured with volumetric software by two radiologists. Intraobserver, interobserver, and interscan variability were analyzed and compared by using the Bland-Altman method and coefficients of variation. The influence of the solid portion of GGNs and GGN size on interscan variability was investigated with multiple linear regression analysis and analysis of variance. RESULTS:Nodule segmentation was successful in 420 of 438 (95.9%) segmentations. As for volume measurement, interscan variability ranged from -17.3% to 18.5%, while intraobserver and interobserver variability ranged from -7.6% to 8.5% and from -11.7% to 18.1%, respectively. Interscan variability in mass measurement ranged from -17.7% to 18.6%, while intraobserver and interobserver variability ranged from -8.4% to 9.4% and from -17.5% to 11.8%, respectively. In the coefficient of variation comparison, there were no significant differences in volume and mass measurements for intraobserver, interscan, and interobserver variability. Measurement variability of volume and mass was not significantly influenced by the presence of a solid portion, solid portion size, or GGN size. CONCLUSION/CONCLUSIONS:Mass measurement of GGNs showed measurement variability from -17.7% to 18.6% and may be a useful method in the follow-up of GGNs with solid portions less than or equal to 5 mm.

OBJECTIVE:The purpose of this article is to assess the usefulness of segmental enhancement inversion on biphasic MDCT in differentiating small (<4 cm) renal oncocytomas from chromophobe renal cell carcinomas (CRCCs). MATERIALS AND METHODS/METHODS:Eighty-two patients (40 men and 42 women) with a mean (±SD) age of 54±12 years (range, 21-75 years) with 27 renal oncocytomas and 55 CRCCs diagnosed by surgery who underwent contrast-enhanced biphasic CT between January 2000 and December 2011 were included. CT scans were interpreted by two radiologists who were blinded to the pathologic findings. The tumors were evaluated for size and segmental enhancement inversion. After independent evaluation, a consensus was reached by measuring the attenuation. Pathologic analysis determined the presence of fibrous septa, cystic change, hemorrhage, and necrosis. The Fisher exact test was used to evaluate the relationship between segmental enhancement inversion, tumor type, and specific pathologic changes. Interobserver concordance was evaluated with kappa statistics. RESULTS:There were no significant differences in size between renal oncocytomas and CRCCs (p=0.458). Segmental enhancement inversion was present in 23, 20, and 21 (25.6%) of the 82 tumors according to reader 1, reader 2, and the consensus, respectively. The agreement was almost perfect (κ=0.843; p<0.001). Segmental enhancement inversion was more common in renal oncocytomas (63% [17/27]) than in CRCCs (7.3% [4/55]; p<0.001). There were no significant relationships between the four pathologic changes and tumor type or segmental enhancement inversion (p=0.351 and p=0.126, respectively). CONCLUSION/CONCLUSIONS:Our study findings suggest that segmental enhancement inversion on biphasic MDCT may be useful in differentiating small renal oncocytomas from CRCCs.

PURPOSE/OBJECTIVE:To prospectively assess the safety and mid-term therapeutic effectiveness of monopolar radiofrequency (RF) ablation with a multiple-electrode switching system for treating small- and medium-sized (≤ 5 cm) hepatocellular carcinomas (HCCs). MATERIALS AND METHODS/METHODS:The institutional review board approved this prospective study, and all patients gave informed consent. From February 2009 to January 2010, 166 patients (110 men and 56 women; age range, 38-86 years; mean age, 62 years ± 10 [standard deviation]) with 166 HCCs less than or equal to 5 cm in diameter were treated with monopolar RF ablation with a multiple-electrode switching system. One of three experienced radiologists performed the RF ablation. Technique effectiveness, ablation volume and time, and major complications were evaluated by means of computed tomography (CT) immediately after RF ablation and at follow-up CT examinations at 1 month and then every 3 months after the procedure. The overall survival, disease-free survival, and local tumor progression-free survival rates were evaluated by using the Kaplan-Meier method. RESULTS:The technique effectiveness rate determined 1 month after RF ablation was 99.4%. Mean ablation parameters were as follows: volume, 85 cm(3) ± 54; maximum diameter, 61 mm ± 13; and minimum diameter, 43 mm ± 11. The major complication rate was 4.8%. The 6-month and 1-, 2-, and 3-year local tumor progression rates were 2%, 6%, 10%, and 11%, respectively. The overall survival rates at 1, 2, and 3 years after RF ablation were 99%, 97%, and 96%, and corresponding local tumor progression-free survival rates were 94%, 90%, and 89%, respectively. The disease-free survival rates at 1, 2, and 3 years after RF ablation were 75%, 60%, and 54%, respectively. CONCLUSION/CONCLUSIONS:Monopolar RF ablation with a multiple-electrode switching system in small- and medium-sized HCCs was safe and efficient, and it provided successful local tumor control and high local tumor progression-free survival rates because an adequate ablation volume was obtained.