Seung Yon Baek

Computer-Aided Evaluation of Breast MRI for the Residual Tumor Extent and Response Monitoring in Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

Objective To evaluate the accuracy of a computer-aided evaluation program (CAE) of breast MRI for the assessment of residual tumor extent and response monitoring in breast cancer patients receiving neoadjuvant chemotherapy. Materials and Methods Fifty-seven patients with breast cancers who underwent neoadjuvant chemotherapy before surgery and dynamic contrast enhanced MRI before and after chemotherapy were included as part of this study. For the assessment of residual tumor extent after completion of chemotherapy, the mean tumor diameters measured by radiologists and CAE were compared to those on histopathology using a paired student t-test. Moreover, the agreement between unidimensional (1D) measurement by radiologist and histopathological size or 1D measurement by CAE and histopathological size was assessed using the Bland-Altman method. For chemotherapy monitoring, we evaluated tumor response through the change in the 1D diameter by a radiologist and CAE and three-dimensional (3D) volumetric change by CAE based on Response Evaluation Criteria in Solid Tumors (RECIST). Agreement between the 1D response by the radiologist versus the 1D response by CAE as well as by the 3D response by CAE were evaluated using weighted kappa (k) statistics. Results For the assessment of residual tumor extent after chemotherapy, the mean tumor diameter measured by radiologists (2.0 ± 1.7 cm) was significantly smaller than the mean histological diameter (2.6 ± 2.3 cm) (p = 0.01), whereas, no significant difference was found between the CAE measurements (mean = 2.2 ± 2.0 cm) and histological diameter (p = 0.19). The mean difference between the 1D measurement by the radiologist and histopathology was 0.6 cm (95% confidence interval: -3.0, 4.3), whereas the difference between CAE and histopathology was 0.4 cm (95% confidence interval: -3.9, 4.7). For the monitoring of response to chemotherapy, the 1D measurement by the radiologist and CAE showed a fair agreement (k = 0.358), while the 1D measurement by the radiologist and 3D measurement by CAE showed poor agreement (k = 0.106). Conclusion CAE for breast MRI is sufficiently accurate for the assessment of residual tumor extent in breast cancer patients receiving neoadjuvant chemotherapy. However, for the assessment of response to chemotherapy, the assessment by the radiologist and CAE showed a fair to poor agreement.

Usefulness of T1-weighted image with fast inversion recovery technique in intracranial lesions: comparison with T1-weighted spin echo image

To evaluate the usefulness of T1-weighted images using the fast inversion recovery (T1FIR) technique as compared with routine T1-weighted spin echo (T1SE) images in various intracranial lesions. Routine spin echo and T1FIR images were performed in 15 consecutive patients with 18 lesions, cerebral infarction in five, astrocytoma in four, vascular lesion in three, encephalomalacia and hemorrhage in each two, arachnoid cyst and meningioma in each one. T1FIR images were performed with 1.5-T Signa [repetition time (TR)/echo time (TE)/inversion time (TI) was 2000/34/800 in 14, 4000/34/1200 in four lesions] and qualitatively compared with the T1SE images in signal intensity, lesion detectability, determination of lesion extent and conspicuity, contrast between lesion and background. Additionally, gray-to-white matter and cerebrospinal fluid (CSF)-to-white matter contrast were evaluated. The signal intensity of the lesions was similar on both T1FIR and T1SE images in all cases. The lesion detectability was similar on both sequences in 15 lesions, and the determination of the lesion extent was definitely higher in 16 lesions on the T1FIR images. Lesion conspicuity was superior in 11, similar in 5, and inferior in 2 patients on the T1FIR images. And also, contrast of lesion-to-background, gray-to-white matter, and CSF-to-white matter was superior on the T1FIR images. The T1FIR technique improved the determination of lesion extent and lesion conspicuity and was qualitatively superior for image contrast as compared with T1SE, but it takes more time than T1SE. The clinical application of T1FIR images depends on whether the superior aspect of the T1FIR images outweighs the disadvantage of the longer time required for this technique.

Assessment of Musculoskeletal Infection in Rats to Determine Usefulness of SPIO-Enhanced MRI

OBJECTIVE The objective of our study was to evaluate the usefulness of superparamagnetic iron oxide (SPIO)-enhanced MRI in experimental models of infectious disease and to analyze the intracellular uptake of SPIO. MATERIALS AND METHODS Nine rats with infectious arthritis of the knee or soft-tissue infection were imaged on an MRI unit on days 4-6 after i.v. injection of a bacterial suspension. All animals were imaged on a T2-weighted fast spin-echo sequence before and 24 hours after administration of SPIO. The nine rats were classified into two groups according to the dose of SPIO. We calculated the relative signal-to-noise ratio (SNR) change and compared the relative SNR change with the histologic findings. We analyzed iron-loaded cells and the intracellular uptake of iron particles according to the dose of SPIO. RESULTS The SNR value decreased in proportion to the increase in the number of iron-laden macrophages or fibroblasts in the wall of the soft-tissue abscess (p < 0.01). The intracellular uptake of iron particles was shown in fibroblasts as well as in macrophages, and their uptake in the fibroblasts was greater than that in the macrophages (p < 0.05). There was no statistically significant difference in the intracellular uptake of iron particles according to the dose of SPIO (p > 0.1). CONCLUSION SPIO-enhanced MRI can be useful in evaluating infectious disease of the joint or soft tissue and is influenced by the uptake of iron particles in fibroblasts as well as macrophages.

Dual-Energy CT in the Assessment of Mediastinal Lymph Nodes: Comparative Study of Virtual Non-Contrast and True Non-Contrast Images

Objective To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. Materials and Methods A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation ≤ the aorta; 1, > the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. Results CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 ± 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (κ value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). Conclusion VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

Reticular infiltrations alone without mass in the mesentery and omentum identified at contrast-enhanced CT: efficacy of US-guided percutaneous core biopsy.

PURPOSE To evaluate the diagnostic efficacy of ultrasonographically (US) guided percutaneous core biopsy of reticular infiltrations alone without mass in the mesentery and omentum at contrast material-enhanced abdominal computed tomography (CT). MATERIALS AND METHODS This study was approved by the institutional review board, and the need for obtaining signed informed consent was waived for this retrospective analysis. From March 2004 to May 2009, 45 patients (mean age, 52.3 years; age range, 21-89 years) with reticular infiltrations alone without mass in the mesentery and omentum at contrast-enhanced abdominal CT underwent US-guided percutaneous core biopsy. Twenty-one men and 24 women were included. The area with the severest infiltrations at CT was targeted during real-time US-guided percutaneous biopsy. Biopsy results were compared with the final results of surgery or follow-up. The diagnostic accuracy of US-guided percutaneous biopsy was then calculated. RESULTS One patient had an insufficient biopsy specimen. Among the 44 patients with sufficient biopsy specimens, 17 patients had malignancy, 12 had tuberculosis, and 15 had nonspecific inflammation. All 29 patients with malignancy and tuberculosis at biopsy had that confirmed with surgery or follow-up results. Two of 15 patients with nonspecific inflammation at percutaneous biopsy were confirmed as having malignancy at surgery and four as having tuberculosis after improvement with empirical antituberculosis therapy. The diagnostic accuracy of US-guided percutaneous biopsy of reticular infiltrations in the mesentery and omentum was 84%; the sensitivity and specificity was, respectively, 89% and 100% for malignancy, 75% and 100% for tuberculosis, and 90% and 83% for nonspecific inflammation. CONCLUSION US-guided percutaneous core biopsy is a feasible diagnostic method with high specificity for confirmative diagnosis of reticular infiltrations alone in the mesentery and omentum at contrast-enhanced CT.

Extrahepatic Soft Tissue Mimicking Applicator-Tract Implantation After Percutaneous Radiofrequency Ablation of Hepatic Malignancy

OBJECTIVE The purpose of our study was to identify extrahepatic soft tissue mimicking applicator-tract implantation after percutaneous radiofrequency ablation of hepatic malignancy on triple-phase dynamic CT. MATERIALS AND METHODS A database was reviewed for 131 patients who underwent percutaneous radiofrequency ablation for treatment of a hepatic tumor over a 3-year period. Patients who developed extrahepatic soft tissue adjacent to the previous ablation zone mimicking applicator-tract implantation were identified. The clinical features of patients, characteristics of extrahepatic soft tissue on CT, soft-tissue changes on follow-up CT, and histopathologic results were evaluated. RESULTS Extrahepatic soft tissue developed in five patients (3.8%) at 2-8 months after percutaneous radiofrequency ablation. Extrahepatic soft tissue showed progressive enhancement during the delayed phase of dynamic CT. Four lesions were completely resolved without any treatment. However, one lesion was enlarged and xanthogranulomatous inflammation was diagnosed by percutaneous biopsy. Univariate analysis showed that an index tumor with a subcapsular location and a prior biopsy had high odds ratios. CONCLUSION The possibility of a benign inflammatory lesion should be considered when extrahepatic soft tissue showing radiologic findings similar to applicator-tract implantation develops after radiofrequency ablation of a hepatic tumor.

Post-Traumatic Arterial Priapism: Colour Doppler Examination and Superselective Arterial Embolization

PURPOSE To evaluate selective embolization for management of post-traumatic priapism and colour Doppler sonography for the diagnosis of the causative lesion and for planning embolization. MATERIALS AND METHODS Six male patients with post-traumatic priapism underwent selective angiography and embolization. Colour Doppler sonography with grey-scale was performed in all six patients before angiography. RESULTS Selective angiography showed intracavernosal arteriovenous fistulas in all patients and pseudoaneurysm of the cavernosal artery (or common penile artery) in three patients. After successful embolization, detumescence was achieved in all patients. Colour Doppler sonography enabled localization and characterization of the lesion causing priapism in four patients. Grey-scale ultrasonography showed the dilated cavernosal sinuses in all patients. CONCLUSION Angiography with selective embolization is safe and effective method to correct post-traumatic priapism. Colour Doppler sonography with grey scale is a useful preangiographic study, as it allows for characterization and localization of the causative lesion except lesions at the proximal cavernosal or distal penile artery near the symphysis pubis.