Gi Hyeon Kim

Locally Advanced Rectal Cancer: Added Value of Diffusion-weighted MR Imaging in the Evaluation of Tumor Response to Neoadjuvant Chemo- and Radiation Therapy

PURPOSE To investigate the added value of diffusion-weighted (DW) magnetic resonance (MR) imaging in the evaluation of complete response (CR) to neoadjuvant combined chemotherapy and radiation therapy (CRT) in patients with locally advanced rectal cancer. MATERIALS AND METHODS Institutional review board approval was obtained for this retrospective study, and the patient informed consent requirement was waived. Forty consecutive patients with locally advanced rectal cancer (>or=T3 or lymph node positive) who underwent CRT and subsequent surgery were enrolled in this study. All patients underwent pre- and post-CRT 1.5-T rectal MR imaging and post-CRT DW MR imaging. For qualitative analysis, two radiologists who were blinded to pathologic staging and prior imaging data retrospectively and independently reviewed conventional MR images and the combined set of MR images and DW MR images over a 2-week interval and recorded their confidence level with respect to the CR to neoadjuvant CRT. Diagnostic accuracy was calculated for each reviewer with receiver operating characteristic (ROC) curve analysis. For quantitative analysis, a third radiologist measured the apparent diffusion coefficient (ADC) of the region of interest three times. Mean ADCs in the CR group were compared with those in the non-CR group. Pathology reports served as the reference standard. RESULTS Diagnostic accuracy (area under the ROC curve [A(z)]) in the evaluation of CR was significantly improved after additional review of DW MR images for both reviewers: For reviewer 1, A(z) improved from 0.676 to 0.876 (P = .005), whereas for reviewer 2, A(z) improved from 0.658 to 0.815 (P = .036). Mean ADC ([1.62 +/- 0.36] x 10(-3) mm(2)/sec) (standard deviation) of the CR group (n = 11) was significantly higher than that ([1.04 +/- 0.24] x 10(-3) mm(2)/sec) of the non-CR group (n = 29) (P < .0001). CONCLUSION Adding DW MR imaging to conventional MR imaging yields better diagnostic accuracy than use of conventional MR imaging alone in the evaluation of CR to neoadjuvant CRT in patients with locally advanced rectal cancer.

Sonography Transmission Gel as Endorectal Contrast Agent for Tumor Visualization in Rectal Cancer

OBJECTIVE The purpose of our study is to show the usefulness and safety of sonography transmission gel as an endorectal contrast agent in preoperative rectal MRI for tumor visualization in rectal cancer. CONCLUSION Sonography transmission gel is an effective and safe endorectal contrast agent for rectal MRI.

Diagnostic accuracy of 3.0-Tesla rectal magnetic resonance imaging in preoperative local staging of primary rectal cancer.

Objectives:To evaluate the diagnostic accuracy of 3.0-T rectal magnetic resonance imaging (MRI) in the preoperative local staging of primary rectal cancer. Materials and Methods:Forty-two patients with surgically and pathologically proven primary rectal cancer who underwent preoperative gadobenate dimeglumine-enhanced 3.0-T rectal MRI, were enrolled in this retrospective study. Two radiologists, who were blinded to the pathology results, independently reviewed the MR images and recorded their confidence level for determination of perirectal extension, and regional lymph node (LN) involvement using a 5-point scale. The diagnostic accuracy of each reviewer for local staging was calculated by receiver operating characteristic (ROC) curve analysis. Interobserver agreement was also calculated using linear weighted &kgr; statistics. Results:The diagnostic accuracy (area under the ROC curve, Az) for determining perirectal extension was for reviewer 1, 0.860 (95% confidence interval, 0.72–0.95) and for reviewer 2, 0.853 (0.71–0.94), respectively. The Az for determination of regional LN involvement was for reviewer 1, 0.902 (0.77–0.97) and for reviewer 2, 0.843 (0.70–0.94), respectively. Interobserver agreement included, respectively, good, and moderate agreement for perirectal extension, and regional LN involvement (&kgr; = 0.662, and 0.522, respectively). Conclusions:3.0-T rectal MRI can provide accurate information of perirectal extension and regional LN involvement in the preoperative local staging of primary rectal cancer.

Added value of 80 kVp images to averaged 120 kVp images in the detection of hepatocellular carcinomas in liver transplantation candidates using dual-source dual-energy MDCT: Results of JAFROC analysis

BACKGROUND To assess the added value of 80 kVp images to weighted average 120 kVp images for detecting hepatocellular carcinomas (HCCs) using dual-source, dual-energy MDCT. MATERIALS AND METHODS Forty-one HCCs in 42 patients who underwent liver transplantation (LT) were included. All patients underwent quadruple-phase CT using a 64-row dual-source, dual-energy MDCT with 80 kVp and 140 kVp. For 120 kVp, a linear blending ratio of 0.3 was chosen. Interval reviews for both simulated 120 kVp images without and with pure 80 kVp data were performed independently by two radiologists. They detected HCCs using a 4-point confidence scale. Tumor-to-liver contrast-to-noise ratio (CNR) was calculated and compared between the 80 kVp and simulated 120 kVp images. The additional diagnostic value of 80 kVp images was evaluated by jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis. RESULTS There were 41 HCCs on pathology and 37 of the 41 HCCs were depicted on CT scan. The mean CNR of the 37 HCCs in late arterial and portal-phase images was significantly better in the 80 kVp images than in 120 kVp images. The average JAFROC figure of merit, however, was not significantly improved when 80 kVp was added. Furthermore, the number of false-positives was significantly increased in reader 1 when adding 80kVp data. CONCLUSION The addition of 80 kVp CT images to simulated 120 kVp images did not significantly improve the detection of HCCs despite of the significantly better CNR of 80 kVp images.

Detection of hepatocellular carcinoma on CT in liver transplant candidates : Comparison of PACS tile and multisynchronized stack modes

OBJECTIVE The objective of our study was to compare CT image interpretation using PACS tile and multisynchronized stack modes with respect to speed and observer performance for the detection of hepatocellular carcinoma (HCC) in liver transplant candidates. MATERIALS AND METHODS Institutional review board approval was obtained, but informed consent was not required for this retrospective study. Sixty-seven patients underwent dynamic multiphasic CT within 3 months before liver transplantation. Interval reviews using tile and multisynchronized stack modes were performed independently by four reviewers with various levels of experience to determine the presence of HCC using a five-point confidence scale. Observer performance was compared using jackknife free-response receiver operating characteristic (ROC) analysis. The time required to interpret the CT scans using each mode was recorded and compared using the paired Students t test. RESULTS Twenty-seven patients had 48 HCC nodules. The mean free-response ROC figures of merit for detecting HCC were significantly higher using the multisynchronized stack mode (0.731) than using the tile mode (0.662) (F-statistic = 6.603, p = 0.012). The 95% CIs for the task were -0.125 - -0.016. The time used for image analysis was also significantly shorter with the stack mode (63 to approximately 75 seconds) than with the tile mode (94 to approximately 191 seconds) for all four reviewers (p < 0.0001). CONCLUSION Multisynchronized stack viewing of multiphasic dynamic CT scans significantly increases the detection rate of HCC in liver transplant candidates. It also significantly shortens the interpretation time compared with tile viewing.

A narrow internal auditory canal with duplication in a patient with congenital sensorineural hearing loss.

A narrow internal auditory canal (IAC) with duplication is a rare anomaly of the temporal bone. It is associated with congenital sensorineural hearing loss. Aplasia or hypoplasia of the vestibulocochlear nerve may cause the hearing loss. We present an unusual case of an isolated narrow IAC with duplication that was detected by a CT scan. In this case, the IAC was divided by a bony septum into an empty stenotic inferoposterior portion and a large anterosuperior portion containing the facial nerve that was clearly delineated on MRI.

A Tailgut Cyst—Cystic Mass Diagnosed by Prenatal Ultrasonography

Tailgut cysts are congenital lesions found in the presacral space. These have been mainly identified in adults and are rare in children, especially neonates. Here, we present the case of a neonate with a presacral cystic mass detected by prenatal ultrasonography that was diagnosed as a tailgut cyst after postnatal surgical removal. When a presacral cyst is encountered, tailgut cyst should be considered in the differential diagnosis.

Endovascular management of hemosuccus pancreaticus, a rare case report of gastrointestinal bleeding.

BackgroundHemorrhage from the pancreatic duct, or hemosuccus pancreaticus (HP), is an unusual cause of intermittent gastrointestinal bleeding. HP is most often diagnosed in patients with chronic pancreatitis, and is usually due to the rupture of an aneurysm in the splenic artery. The traditional treatment for HP is surgery, although most cases can be managed by angioembolization.Case PresentationWe present a case of HP in a patient with no history or evidence of chronic pancreatitis. Repeated endoscopy revealed fresh bleeding from the papilla of Vater. Angiography revealed an aneurysm of the splenic artery, which was the suspected cause of the intermittent bleeding from the pancreatic duct. Angiography demonstrated extravasation of contrast from the aneurysm. A peripheral Jostent stent-graft was hand-mounted on an angioplasty balloon and then inserted into the aneurysm. Arteriography revealed successful occlusion of the aneurysm with the stent-graft. No recurrent gastrointestinal bleeding was observed during the five years follow-up periods.ConclusionHP should be included in the differential diagnosis of intermittent gastrointestinal bleeding in patients with histories of chronic alcoholism, even when they do not have a history of chronic pancreatitis. We recommend an interventional procedure with a metal stent for the initial treatment of HP.