Dae Jung Kim

Restaging of Rectal Cancer with MR Imaging after Concurrent Chemotherapy and Radiation Therapy

In patients with rectal cancer who have received concurrent chemotherapy and radiation therapy (CCRT) before surgery, magnetic resonance (MR) imaging has low accuracy in prediction of the pathologic stage owing to overstaging or understaging. The factors related to this problem include fibrosis, desmoplastic reaction, edema, inflammation, and viable tumor nets at a fibrotic scar from a previous tumor. Preoperative diagnosis with MR imaging of histologic variants of rectal adenocarcinoma, especially mucinous adenocarcinoma, is important because these variants tend to have a poor response to CCRT. In addition, these variants manifest with high signal intensity on T2-weighted images after CCRT; this finding makes it difficult to differentiate residual tumors from remaining mucin pools. MR volumetry and functional MR imaging may be helpful in prediction and assessment of tumor response to CCRT. Awareness of post-CCRT changes helps radiologists achieve appropriate restaging of irradiated rectal cancer with MR imaging and can lead to a reduction in understaging or overstaging. It is important to obtain and compare both pre- and post-CCRT images before interpreting the post-CCRT images.

Nodal staging of rectal cancer: high-resolution pelvic MRI versus ¹⁸F-FDGPET/CT.

Aim: To compare high-resolution pelvic magnetic resonance imaging (MRI) with positron emission tomography (PET)/computed tomography (CT) for the preoperative assessment of nodal staging in rectal cancer. Materials and Methods: Thirty patients who had surgery for rectal cancer were retrospectively enrolled during a 6-month period. Each patient underwent high-resolution pelvic MRI and PET/CT preoperatively within the same week. An experienced radiologist predicted nodal staging on MR, and an experienced nuclear medicine physician similarly predicted nodal staging on PET/CT. Their predictions were compared with pathologic staging results, retrospectively. Results: The accuracies of nodal status prediction from MR and PET/CT were 83% and 70%, respectively. Magnetic resonance imaging had a sensitivity of 94% and a specificity of 67%, whereas PET/CT had a sensitivity of 61% and a specificity of 83%. A combination of MRI and PET/CT revealed a sensitivity of 94%, a specificity of 83%, and an accuracy of 90%. Conclusion: High-resolution pelvic MRI was more accurate than PET/CT for the prediction of regional nodal status. Magnetic resonance imaging had a high sensitivity and PET/CT had a high specificity for N staging in rectal cancer.

Detection of small intrahepatic metastases of hepatocellular carcinomas using diffusion-weighted imaging: comparison with conventional dynamic MRI

PURPOSEnThe purpose of our study was to compare diffusion-weighted MR imaging (DWI) with conventional dynamic MRI in terms of the assessment of small intrahepatic metastases from hepatocellular carcinoma (HCC).nnnMATERIALS AND METHODSnIn 24 patients with multifocal, small (≤2 cm) intrahepatic metastatic foci of advanced HCC, a total of 134 lesions (≤1 cm, n=81; >1 cm, n=53) were subjected to a comparative analysis of hepatic MRI including static and gadopentetate dimeglumine-enhanced dynamic imaging, and DWI using a single-shot spin-echo echo-planar MRI (b values=50, 400 and 800 s/mm(2)), by two independent reviewers.nnnRESULTSnA larger number of the lesions were detected and diagnosed as intrahepatic metastases on DWI [Reviewer 1, 121 (90%); Reviewer 2, 117 (87%)] than on dynamic imaging [Reviewer 1, 107 (80%); Reviewer 2, 105 (78%)] (P<.05). For the 81 smaller lesions (≤1 cm), DWI was able to detect more lesions than dynamic imaging [Reviewer 1, 68 (84%) vs. 56 (69%), P=.008; Reviewer 2, 65 (80%) vs. 55 (68%), P=.031], but there was no statistically significant difference between the two image sets for larger (>1 cm) lesions.nnnCONCLUSIONnDue to its higher detection rate of subcentimeter lesions, DWI could be considered complementary to dynamic MRI in the diagnosis of intrahepatic metastases of HCCs.

Adrenocortical oncocytoma displaying intense activity on 18F-FDG-PET: a case report and a literature review

We report on the 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) findings in a case of adrenocortical oncocytoma, a rare tumor of the adrenal gland with the literature review of other imaging findings including ultrasonography, computed tomography, and magnetic resonance imaging. To our knowledge, there have been no reports published in the English literature about 18F-FDG-PET findings in adrenocortical oncocytoma.

Hypervascular hepatocellular carcinoma in the cirrhotic liver: diffusion-weighted imaging versus superparamagnetic iron oxide-enhanced MRI

PURPOSEnThe purpose of the study was to validate diffusion-weighted imaging (DWI) in the assessment of hypervascular hepatocellular carcinoma (HCC) compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the cirrhotic liver.nnnMATERIAL AND METHODSnForty-six consecutive patients with 106 hypervascular focal lesions in the cirrhotic liver who underwent DWI using three b factors and gadopentetate dimeglumine-enhanced dynamic MRI followed by SPIO-enhanced MRI were enrolled. Two independent radiologists evaluated two separated image sets (SPIO set, dynamic MRI and SPIO-enhanced T2*-weighted images; DWI set, DWI and dynamic MRI) and assigned confidence levels for diagnosis of HCC using a five-point scale for each lesion. Area under the receiver operating characteristic curve (A(z)) was calculated for each image set.nnnRESULTSnThe A(z) value of the DWI set was larger than the SPIO set by both readers (reader 1, 0.936 vs. 0.900, P=.050; reader 2, 0.938 vs. 0.905, P=.110). For the sensitivity (reader 1, 93.1% vs. 86.2%, P=.146; reader 2, 95.4% vs. 88.5%, P=.070) and specificity (reader 1, 89.5% vs. 73.7%, P=.250; reader 2, 79.0% vs. 73.7%, P=1.000) of HCC diagnosis, DWI sets were superior to SPIO sets without statistically significant differences.nnnCONCLUSIONnFor assessment of hypervascular HCC, DWI in combination with dynamic MRI provides comparable or slightly better information compared with the combination of dynamic and SPIO-enhanced MRI.

A simple method for the removal of thiols on gold surfaces using an NH4OH-H2O2-H2O solution.

The removal behavior of self-assembled monolayers (SAMs) of thiol molecules on a gold substrate by an NH(4)OH-H(2)O(2)-H(2)O solution was studied using attenuated total reflectance infrared spectroscopy (ATR-IR) and atomic force microscopy (AFM). Furthermore, the impact of the concentration of NH(4)OH and H(2)O(2) in the solution and reaction temperature on the SAM removal rate and efficiency was explored. The SAM removal rate and efficiency were significantly influenced by the concentration of NH(4)OH rather than H(2)O(2). The solution containing the 2 : 1 molar ratio of NH(4)OH : H(2)O(2) among three different solutions showed the highest removal rate and efficiency in the removal of 11-mercapto-1-undecanol. The increase in the reaction temperature resulted in the enhancement on the SAM removal rate, but it led to the fast delamination of the gold layer. These results may be useful in the regeneration of sensor surfaces relying on gold/thiol chemistry.

Localized cystic disease of the kidney: CT findings

AbstractBackground: We assessed the clinical and computed tomographic (CT) features of localized cystic disease of the kidney and how these features differentiate this disease from other renal cystic diseases.nMethods: Medical records and CT scans of seven patients with localized cystic disease were reviewed retrospectively. Pathologic confirmation in five patients was done by surgery. The subjects consisted of four males and three females, with an age range of 29–74 years.nResults: Localized cystic disease in five patients was an incidental finding. Clinical presentations in the other two patients included dark urine color, palpable flank mass, and generalized weakness. There was no patient with impairment of renal function associated with renal cystic disease. Six patients had cystic renal lesions in the left kidneys, and one patient had lesions in the right kidney. Six patients had cysts in a localized area in the affected kidney, and the remaining patient had diffuse involvement of the entire kidney. The upper pole was most frequently involved. CT appearance was characterized by multiple, variable size cysts conglomerated to islets of cysts that were separated by the normal renal parenchymal band.nConclusion: Localized cystic disease of the kidney has characteristic CT findings that distinguish it from other renal cystic diseases, making follow-up without surgical intervention possible.

Diagnosis of hepatocellular carcinoma with gadoxetic acid-enhanced MRI: 2016 consensus recommendations of the korean society of abdominal radiology

Diagnosis of hepatocellular carcinoma (HCC) with gadoxetic acid-enhanced liver magnetic resonance imaging (MRI) poses certain unique challenges beyond the scope of current guidelines. The regional heterogeneity of HCC in demographic characteristics, prevalence, surveillance, and socioeconomic status necessitates different treatment approaches, leading to variations in survival outcomes. Considering the medical practices in Korea, the Korean Society of Abdominal Radiology (KSAR) study group for liver diseases has developed expert consensus recommendations for diagnosis of HCC by gadoxetic acid-enhanced MRI with updated perspectives, using a modified Delphi method. During the 39th Scientific Assembly and Annual Meeting of KSAR (2016), consensus was reached on 12 of 16 statements. These recommendations might serve to ensure a more standardized diagnosis of HCC by gadoxetic acid-enhanced MRI.

Evaluation of Lateral Pelvic Nodes in Patients With Advanced Rectal Cancer

OBJECTIVEnThe purpose of this article is to discuss the importance of lateral pelvic lymph node metastasis as a predictor of local recurrence and survival in patients with advanced rectal cancer.nnnCONCLUSIONnPrediction of lateral pelvic nodal staging on MRI shows high accuracy compared with the other imaging modalities. Diffusion-weighted MRI or (18)F-FDG PET/CT may be helpful to assesses lateral pelvic lymph node metastasis.

Usefulness of a lead shielding device for reducing the radiation dose to tissues outside the primary beams during CT

PurposeThis study was done to investigate the efficacy of a lead shield in protecting the tissues outside the primary beams, such as the breast and thyroid, by measurement of the entrance skin dose during CT of the brain, neck, abdomen, and lumbar spine.Materials and methodsInstitutional Review Board approval was obtained. This study included 150 patients (male:femalexa025:125, age range 15–45xa0years). In females, brain, lumbar spine, and abdominal CT scans, pre-/post-contrast neck CT scans, and post-contrast liver dynamic CT scans were performed. In males, brain CT scans only were performed. Breast shielding was performed in all females, and thyroid shielding was conducted in patients with brain CT. During all CT studies, the left breast or left thyroid was shielded using a lead shield, and the contralateral side was left unshielded. Thus, each breast or thyroid measurement had its own control for the same demographic data. The efficacy of the shielding of both breasts and thyroids during CT was assessed.ResultsDuring brain, abdominal, lumbar, pre-/post-contrast neck, and post-contrast liver dynamic CT, 33.5, 26.0, 17.4, 26.5, and 16.2xa0% of the breast skin dose were reduced, respectively. During brain CT, the thyroid skin dose was reduced by 17.9xa0% (females) and 20.6xa0% (males). There were statistically significant differences in the skin doses of shielded organs (pxa0<xa00.05). Breast shielding during neck and liver dynamic CT was the most effective compared with breast or thyroid shielding during other CT scans.ConclusionsWe recommend breast shielding during neck and liver dynamic CT in young female patients to avoid unnecessary radiation exposure.