Faculty Bibliography

OBJECTIVE:The objective of our study was to evaluate apparent diffusion coefficient (ADC) and various ADC ratios in determining aggressiveness of prostate cancer. MATERIALS AND METHODS/METHODS:One hundred sixty-five patients with biopsy-proven prostate cancer underwent 3-T MRI followed by radical prostatectomy. ADC and ADC ratios were calculated using the peripheral zone, transition zone, same zone as the tumor, and urinary bladder as references. ADC and ADC ratios were correlated with Gleason score using the Spearman correlation coefficient (ρ) and were compared between low-grade (Gleason score = 6) and high-grade (Gleason score ≥ 7) prostate cancer using the unpaired t test. ROC curves were used to compare diagnostic accuracies of ADC and ADC ratios in determining high-grade prostate cancer. RESULTS:Fifty-six (33.9%) and 109 (66.1%) patients had low- and high-grade prostate cancer, respectively. ADC (ρ = -0.476) and all ADC ratios (ρ = -0.397, -0.412, -0.381, and -0.474, respectively) correlated significantly with Gleason score (p < 0.001) and were significantly lower in patients with high-grade prostate cancer (p < 0.001). For predicting high-grade prostate cancer, tumor ADC and tumor-to-urinary bladder ADC ratio showed the highest AUC (0.794 and 0.790, respectively) but without statistically significant difference (p = 0.803). AUC of tumor ADC (0.794) was statistically significantly higher than those of the tumor-to-peripheral zone and tumor-to-transition zone ADC ratios (0.746, p = 0.039; 0.751, p = 0.027; respectively). AUC of tumor ADC was not statistically significantly higher than that of the tumor-to-tumor zone ADC ratio (0.763, p = 0.193). AUC calculated using the tumor-to-urinary bladder ADC ratio was statistically significantly higher than that using the tumor-to-transition zone ADC ratio (p = 0.028) and marginally higher than that from tumor-to-peripheral zone ADC ratio (p = 0.080). Otherwise, no significant differences were seen in the AUCs (p = 0.193-0.828). CONCLUSION/CONCLUSIONS:Both ADC and various ADC ratios correlated significantly with Gleason score and were significant predictors of high-grade prostate cancer. However, no benefit was found in using ADC ratio over ADC.

OBJECTIVE:The purpose of this study was to evaluate whether routine prostate MRI is adequate for detection of bone metastasis in patients with newly diagnosed prostate cancer. MATERIALS AND METHODS/METHODS:The study included 308 patients with newly diagnosed prostate cancer who underwent prostate MRI. Two radiologists categorized MRI findings as normal, metastasis, or equivocal. Histologic analysis or best valuable comparator based on comprehensive review of images and clinical follow-up studies were used as reference standards. Clinicopathologic variables and MRI findings were compared between patients with and those without bone metastasis by use of chi-square and t tests. The diagnostic performance of prostate MRI for detecting bone metastasis was assessed by ROC analysis. Subgroup analysis was performed for patients at high risk of bone metastasis. RESULTS:Twenty-one (6.8%) patients had bone metastasis. They had significantly higher prostate-specific antigen levels (p = 0.015) and Gleason scores (p < 0.001) than those without bone metastasis. The diagnostic performance of MRI was as follows: sensitivity, 95.2%; specificity, 99-100%; positive predictive value, 86.9-100%; negative predictive value, 99.7%. For 119 patients at high risk of bone metastasis, these values were 95%, 100%, 100%, and 99%. Only 1 of the 21 (4.8%) patients had bone metastasis only in an area not explored with prostate MRI, that is, the thoracic spine. CONCLUSION/CONCLUSIONS:The diagnostic performance of routine prostate MRI for identifying bone metastasis in patients with newly diagnosed prostate cancer was excellent.

Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to important electronic and magnetic phase transitions. Therefore, experimental approaches toward understanding the role of defects in complex oxides have been largely limited to controlling O vacancies. In this study, we report on the selective formation of different types of elemental vacancies and their individual roles in determining the atomic and electronic structures of perovskite SrTiO3 (STO) homoepitaxial thin films fabricated by pulsed laser epitaxy. Structural and electronic transitions have been achieved via selective control of the Sr and O vacancy concentrations, respectively, indicating a decoupling between the two phase transitions. In particular, O vacancies were responsible for metal-insulator transitions, but did not influence the Sr vacancy induced cubic-to-tetragonal structural transition in epitaxial STO thin film. The independent control of multiple phase transitions in complex oxides by exploiting selective vacancy engineering opens up an unprecedented opportunity toward understanding and customizing complex oxide thin films.

BACKGROUND:Exophytic renal angiomyolipoma and liposarcoma are two representative tumors in the retroperitoneum with fatty components that have potential to be misdiagnosed with each other. PURPOSE/OBJECTIVE:To compare the computed tomography (CT) findings of exophytic renal angiomyolipoma and perirenal liposarcoma. MATERIAL AND METHODS/METHODS:Fourteen and 16 cases with histologically-proven exophytic renal angiomyolipoma and perirenal liposarcoma, respectively, with preoperative CT from January 2000 to December 2013 were reviewed by two radiologists blinded to the clinical and pathological findings for an array of CT findings. These findings were compared between exophytic renal angiomyolipoma and perirenal liposarcoma using the Student t-test and Fisher's exact test. RESULTS:Patients with exophytic renal angiomyolipoma were younger (P = 0.001) without differences in sex (P = 1.000). Exophytic renal angiomyolipomas were smaller (P = 0.004) and more commonly showed the following findings: renal parenchymal defect (P < 0.001), multiple linear vessels (P = 0.026), aneurysmal dilatation of intratumoral vessels (P = 0.024), renal parenchymal vascular pedicle (P < 0.001), hemorrhage (P = 0.037), encapsulated margin (P = 0.001), and other intrarenal fatty lesions (P = 0.037). No significant difference was seen in laterality, renal hilar vascular pedicle, non-fatty soft tissue nodule, calcification, or kidney displacement (P = 0.236-1.000). CONCLUSION/CONCLUSIONS:Several CT findings were significantly different between exophytic renal angiomyolipoma and perirenal liposarcoma and may be helpful for differentiating between the two entities when confronting a fatty mass in the perirenal space.

OBJECTIVE:The purpose of this study was to evaluate the added clinical value of PET/MRI compared with conventional contrast-enhanced MDCT (CECT) alone in the evaluation of patients with colorectal cancer. MATERIALS AND METHODS/METHODS:The study population comprised 51 patients with colorectal cancer who underwent (18)F-FDG PET/MRI and CECT within a 90-day interval between October 2012 and August 2013. Two reviewers in consensus evaluated whether PET/MRI added value to CECT for lesion detection and characterization and assessed whether changes in treatment strategies were made. The malignancy probability of each lesion was assessed on a 5-point scale. ROC analyses were performed with histopathologic findings, imaging, and clinical follow-up as the reference standards. Two reviewers evaluated the presence or absence of pulmonary metastatic nodules on PET/MR images that had been detected on chest CT scans. RESULTS:PET/MRI added value to CECT for 14 of 51 patients (27.5%) in terms of better characterization (12/51 [23.5%]) and additional detection (2/51 [3.9%]) of extracolonic lesions. The additional information from PET/MRI led to a change in treatment strategy for 11 of 51 (21.6%) patients. ROC analyses showed that PET/MRI was significantly superior to CT in depicting colorectal cancer (p < 0.05). The rate of detection of pulmonary metastatic nodules with PET/MRI was 52.9% (9/17). CONCLUSION/CONCLUSIONS:Integrated whole-body PET/MRI added value to CECT in the detection of metastatic lesions and characterization of indeterminate lesions, albeit with limited performance for small pulmonary metastatic nodules. The results suggest that PET/MRI may aid in the selection of more appropriate treatment strategies for patients with colorectal cancer.

PURPOSE/OBJECTIVE:The purpose of this study is to compare the MRI features of intestinal and endocervical mucinous borderline ovarian tumors (MBOT). METHODS:Fifty seven and 17 patients with histologically proven intestinal (n = 62) and endocervical (n = 22) MBOT, respectively, underwent preoperative MRI which were reviewed by two radiologists blinded to histology. An array of MRI features and clinical factors (age, cancer antigen 125 [CA-125]) were compared between intestinal and endocervical subtypes using the t test and Chi-square test. Univariate and multivariate logistic regression analyses were performed to evaluate for significant predictors of subtype. RESULTS:There was no significant difference in patient age of intestinal and endocervical MBOT (P = 0.423). CA-125 levels were higher in endocervical MBOT (P = 0.022). Regarding MR features, intestinal MBOT was larger, had more septations, more frequently demonstrated honeycomb loculi, and signal intensity discrepancy while endocervical MBOT was more frequently bilateral with papillary projections (P < 0.05). At multivariate analysis, higher CA-125 (odds ratio [OR] 1.015, P = 0.034) and the presence of papillary projections (OR 11.441, P = 0.024) were the only independent predictive factors of endocervical MBOT. CONCLUSION/CONCLUSIONS:Intestinal and endocervical subtypes of MBOT demonstrated significantly different features on MRI. The presence of papillary projection was the only independent MRI feature predictive of endocervical MBOT.

OBJECTIVE:To evaluate whether switching bipolar radiofrequency ablation (SB-RFA) using three internally cooled wet (ICW) electrodes can induce coagulations >5 cm in porcine livers with better efficiency than consecutive monopolar (CM) or switching monopolar (SM) modes. METHODS:A total of 60 coagulations were made in 15 in vivo porcine livers using three 17-gauge ICW electrodes and a multichannel radiofrequency (RF) generator. RF energy (approximately 200 W) was applied in CM mode (Group A, n = 20) for 24 min, SM mode for 12 min (Group B, n = 20) or switching bipolar (SB) mode for 12 min (Group C, n = 20) in in vivo porcine livers. Thereafter, the delivered RFA energy, as well as the shape and dimension of coagulations were compared among the groups. RESULTS:Spherical- or oval-shaped ablations were created in 30% (6/20), 85% (17/20) and 90% (18/20) of coagulations in the CM, SM and SB groups, respectively (p = 0.003). SB-RFA created ablations >5 cm in minimum diameter (Dmin) in 65% (13/20) of porcine livers, whereas SM- or CM-RFA created ablations >5 cm in only 25% (5/20) and 20% (4/20) of porcine livers, respectively (p = 0.03). The mean Dmin of coagulations was significantly larger in Group C than in Groups A and B (5.1 ± 0.9, 3.9 ± 1.2 and 4.4 ± 1.0 cm, respectively, p = 0.002) at a lower delivered RF energy level (76.8 ± 14.3, 120.9 ± 24.5 and 114.2 ± 18.3 kJ, respectively, p < 0.001). CONCLUSION/CONCLUSIONS:SB-RFA using three ICW electrodes can create coagulations >5 cm in diameter with better efficiency than do SM- or CM-RFA. ADVANCES IN KNOWLEDGE/CONCLUSIONS:SB-RFA can create large, regular ablation zones with better time-energy efficiency than do CM- or SM-RFA.

PURPOSE/OBJECTIVE:This study was designed to evaluate the efficacy and safety in performing chemoembolization of extrahepatic collateral arteries (EHC) for hepatocellular carcinoma (HCC) located in the caudate lobe. METHODS:Between January 2006 and November 2013, chemoembolization via EHC was performed in 35 patients with 35 caudate HCCs. Preprocedural and follow-up CT or MR scans, angiographic images, and medical records were reviewed retrospectively in consensus. Chi-square analysis was used to evaluate the relationship between tumor characteristics and type of EHC and that between tumor response and the characteristics of the tumor and chemoembolization. RESULTS:In 31 (88.6 %) patients, EHCs supplying the caudate HCC originated from the right inferior phrenic artery (RIPA). The remaining four HCCs were supplied by the gastroduodenal artery, dorsal pancreatic artery, and right and left gastric arteries. Superselective catheterization of tumor-feeding vessels from the EHC was achieved in 27 patients (77.1 %). There were no major complications. Individual tumor response supplied by the EHC at follow-up contrast-enhanced CT were as follows: complete response (n = 18), partial response (n = 9), stable disease (n = 3), and progressive disease (n = 3). Non-RIPA EHCs were significantly more common in patients who had previously received chemoembolization via the RIPA (50 %) than those who had not (6.5 %; P = 0.01). There was no significant predictive factor associated with tumor response. CONCLUSIONS:HCC in the caudate lobe can be supplied by several EHCs. Chemoembolization via these arteries can be performed safely and effectively.

Comparison between single- and the poly-crystalline structures provides essential information on the role of long-range translational symmetry and grain boundaries. In particular, by comparing single- and poly-crystalline transition metal oxides (TMOs), one can study intriguing physical phenomena such as electronic and ionic conduction at the grain boundaries, phonon propagation, and various domain properties. In order to make an accurate comparison, however, both single- and poly-crystalline samples should have the same quality, e.g., stoichiometry, crystallinity, thickness, etc. Here, by studying the surface properties of atomically flat poly-crystalline SrTiO3 (STO), we propose an approach to simultaneously fabricate both single- and poly-crystalline epitaxial TMO thin films on STO substrates. In order to grow TMOs epitaxially with atomic precision, an atomically flat, single-terminated surface of the substrate is a prerequisite. We first examined (100), (110), and (111) oriented single-crystalline STO surfaces, which required different annealing conditions to achieve atomically flat surfaces, depending on the surface energy. A poly-crystalline STO surface was then prepared at the optimum condition for which all the domains with different crystallographic orientations could be successfully flattened. Based on our atomically flat poly-crystalline STO substrates, we envision expansion of the studies regarding the TMO domains and grain boundaries.