Yedaun Lee

Apparent diffusion coefficient for discriminating metastatic from non-metastatic lymph nodes in primary rectal cancer.

OBJECTIVE To investigate whether the apparent diffusion coefficient (ADC) could be used to discriminate metastatic from non-metastatic lymph nodes (LNs) in patients with primary rectal cancer. METHODS This study investigated 34 patients (male: 12, female: 22, mean: 62.7, range: 37-82) who underwent 1.5-T MRI with diffusion-weighted imaging (DWI) and subsequent surgical resection. A blinded radiologist measured the ADC value in each regional LN after referring to the T2-weighted images and DWI. The t-test was used to compare the mean ADC values of the metastatic and non-metastatic LNs. A ROC analysis was performed to calculate the diagnostic performance and obtain the optimal cut-off. The histopathological results were used as the reference standard. RESULTS 114 LNs (46 metastatic and 68 non-metastatic) were matched and analyzed. The mean ADC of the metastatic LNs was significantly lower than that of the non-metastatic LNs (0.9 ± 0.15 × 10(-3) mm(2)/s; 1.1 ± 0.22 × 10(-3) mm(2)/s, P<0.0001). The area under the ROC curve was 0.734 (95% confidence interval, 0.644-0.812). When an ADC value of 1.0 × 10(-3) mm(2)/s was used as the cut-off, a maximum accuracy of 72% was calculated (sensitivity, 78%; specificity, 67%). CONCLUSIONS Although ADC could be used to discriminate metastatic from non-metastatic LNs, the diagnostic accuracy is approximately 70%.

Intravoxel incoherent motion diffusion-weighted MRI of the abdomen: The effect of fitting algorithms on the accuracy and reliability of the parameters.

To evaluate the influence of fitting methods on the accuracy and reliability of intravoxel incoherent motion (IVIM) parameters, with a particular emphasis on the constraint function.

Association of non-alcoholic fatty liver disease with renal stone disease detected on computed tomography

Objective To evaluate the association between Non-alcoholic fatty liver disease (NAFLD) with renal stone disease detected on computed tomography (CT). Method A total 1812 patients who underwent abdomen-pelvis CT in July 2015 were included in this study. The inclusion criteria for NAFLD were as follows: (i) lower average Hounsfield unit (HU) of hepatic right lobe, left medial and lateral segment when compared with that of spleen, (ii) patients who having urolithiasis in kidneys, ureters and urinary bladder, and (iii) patients underwent abdomen-pelvis CT including noncontrast image. The statistical significance of the association between NAFLD and renal stone disease was assessed using Chi Square Test. The Odds ratios and 95% CI were calculated to assess the propensity of renal stones disease for NAFLD by using Logistic Regression analysis. Results The frequency of renal stone disease in patients with NAFLD was higher approximately 19% than those who having renal stone disease without NAFLD. In addition, the presence of NAFLD was linked with renal stone disease showing that detection rate of renal stone disease in patients with NAFLD was markedly high (odds ratio: 5, 95% CI, 3–8.2) (p < 0.05) in multivariate analysis. Conclusion The presence of significant association between NAFLD with renal stone disease and NAFLD may be considered to be an independent variable as a risk factor for renal stone disease.

Comparison of T2-weighted imaging, diffusion-weighted imaging and contrast-enhanced T1-weighted MR imaging for evaluating perianal fistulas

PURPOSE To compare the lesion conspicuity and diagnostic performance of three imaging data sets (T2WI, combined T2WI and DWI [combined DWI], contrast-enhanced (CE)-T1WI) in assessing perianal fistulas. METHODS Two radiologists with 7 and 15years of experience assessed 28 fistulas from 24 patients in each image set. RESULTS The lesion conspicuity was improved for only one reader after reading the combined DWI (P=0.0039) and CE-T1WI (P=0.0215). The accuracy was stationary for fistula type (reader 1, all 93%; reader 2, all 89%) or for direction of internal opening (96% for all sets; 92% for CE-T1WI). CONCLUSION Although combined DWI and CE-T1WI might improve fistula conspicuity, they showed comparable diagnostic performance to T2WI.

Metachronous colonic metastasis from pancreatic cancer presenting as mechanical obstruction: a case report

Colonic metastasis from pancreatic cancer is extremely rare. We present the case of a 64-year-old man who developed colonic metastasis of pancreatic cancer 2 years after distal pancreatectomy. The level of carbohydrate antigen 19-9 (CA19-9) was elevated to 5133.0 U/ml. Pathologic diagnosis was a metastasis from the primary pancreatic cancer. Based on the present case, colonic metastasis should be included in the differential diagnosis of colonic mass with elevated CA 19-9 and history of curative resection of primary pancreatic cancer.

Added value of morphologic characteristics on diffusion-weighted images for characterizing lymph nodes in primary rectal cancer

To evaluate the added value of the morphologic features of lymph nodes (LNs) on diffusion-weighted images (DWI), an interval reading was performed for the T2-weighted images (T2WI) and the combined image set (T2WI and DWI) using extracted imaging characteristics from 54 metastatic and 172 benign LNs in 44 patients with primary rectal cancer. The specificity and accuracy increased after adding DWI to T2WI for both readers (specificity: from 59% to 73% and from 41% to 68% for readers 1 and 2, respectively; accuracy: from 58% to 68% and from 44% to 64% for readers 1 and 2, respectively, P<.0001).

Detection of an accidentally implanted wooden foreign body using CT: case report and literature review

Regardless of advancement in imaging techniques, the recognition of vegetative foreign bodies in the abdomen remains a difficult task. Simple radiography and computed tomography will ignore radiolucent foreign bodies. Here, we report the case of a 34-year-old man with a penetrating injury to the abdomen caused by a radiolucent wooden foreign body that was not initially detected. However, imaging can be specific and reliably diagnostic when performed in the appropriate clinical setting. Multidetector computed tomography is frequently underused but has proven useful for the assessment of retained wooden foreign bodies in the abdomen.

Merkel Cell Carcinoma of the Axilla and Adrenal Gland: A Case Report with Imaging and Pathologic Findings

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine carcinoma of the skin. MCC is characterized by a high incidence of locoregional recurrence, and distant metastasis, and often requires short-term follow-up after treatment. In this present paper, we describe a rare case of MCC, which presented as a palpable axillary mass and an incidental adrenal mass, and report on the ultrasonography, computed tomography, and 18F-fluorodeoxyglucose-positron emission tomography findings. The patient underwent surgery and adjuvant radiation therapy. Seven months after the initial diagnosis, distant metastasis was detected during a follow-up examination.

Study on the feasibility of the HgI2 dosimeter for quality assurance of radiotherapy

In radiotherapy, a variety of detectors such as ionization chambers, films, TLDs, diodes, and OSL, are being used for quality assurance (QA). Owing to its high sensitivity and feasibility to operate at low voltages, silicon (Si) photoconductors, which are used as detection material of a diode, are currently being used as relative dosimeters. In addition, other materials such as amorphous selenium (a-Se), cadmium telluride (CdTe), lead iodide (PbI2), and mercury iodide (HgI2) were also being investigated for their feasibility as diagnostic radiation detector. Among these materials, HgI2 has been reported to show remarkable properties including high spatial resolution and high stopping power. Hence In this study, we have verified the feasibility of HgI2 dosimeter for quality assurance of radiotherapy. In order to fabricate the detector, HgI2 was mixed with TiO2 to minimize the signal reduction. Following this, the resulting mixture was deposited onto indium tin oxide (ITO) coated glass by particle-in binder (PIB) method. Finally, the top ITO electrode was coated by magnetron sputterring system. Subsequently, we measured the electrical properties generated by high-energy radiation from linear accelerator (LINAC), and analyzed the reproducibility, linearity, and percent depth dose (PDD) of the fabricated detoctor. In addition, we have determined the build-up materials in experimental setup, since the thickness of build-up region, where the secondary electron emission equilibrium occurs, changes depending on radiation energy. It was observed that the relative variations measured as standard deviation divided by the average value among repeated measurements was approximately 1%. Deviations from linearity are smaller than 5%. Finally, we compared the experimental data of the detector fabricated in this study with those of the farmer-type ionization chamber. Base on the results obtained from this study, it could be realized that HgI2 could be used as dosimeter for QA of radiotherapy.

Comparison of Model-Based Iterative Reconstruction, Adaptive Statistical Iterative Reconstruction, and Filtered Back Projection for Detecting Hepatic Metastases on Submillisievert Low-Dose Computed Tomography.

Objective The aim of the study was to compare the diagnostic performance of model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP) on submillisievert low-dose computed tomography (LDCT) for detecting hepatic metastases. Methods Thirty-eight patients having hepatic metastases underwent abdomen CT. Computed tomography protocol consisted of routine standard-dose portal venous phase scan (120 kVp) and 90-second delayed low-dose scan (80 kVp). The LDCT images were reconstructed with FBP, ASIR, and MBIR, respectively. Two readers recorded the number of hepatic metastases on each image set. Results A total of 105 metastatic lesions were analyzed. For reader 1, sensitivity for detecting metastases was stationary between FBP (49%) and ASIR (52%, P = 0.0697); however, sensitivity increased in MBIR (66%, P = 0.0035). For reader 2, it was stationary for all the following sets: FBP (65%), ASIR (68%), and MBIR (67%, P > 0.05). Conclusions The MBIR and ASIR showed a limited sensitivity for detecting hepatic metastases in submillisievert LDCT.