Hyo Soon Lim

FDG PET/CT for the Detection and Evaluation of Breast Diseases: Usefulness and Limitations

Positron emission tomography (PET) with fluorine 18 fluorodeoxyglucose (FDG) is used to diagnose, stage, and monitor breast cancer. FDG PET has the capability to depict abnormal metabolic activity before any anatomic change occurs; however, in the absence of identifiable anatomic structures on PET images, it may be impossible to identify the location of areas of increased radionuclide uptake. In such cases, the coregistration of PET images with images from computed tomography (CT) may help improve diagnostic accuracy and lead to better clinical management of patients with breast cancer. Although FDG PET/CT may have limited diagnostic value for detecting small primary breast tumors, well-differentiated breast cancer, or regional lymph node involvement, it is superior to conventional imaging modalities for detecting distant metastases and recurrences and for monitoring the response to therapy.

Imaging features of hepatocellular carcinoma after transcatheter arterial chemoembolization and radiofrequency ablation.

OBJECTIVE The purpose of this pictorial essay is to show the imaging features of hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) and radiofrequency thermal ablation on CT, MRI, and contrast-enhanced sonography and to describe the advantages and limitations of each imaging technique in evaluating the therapeutic effect on HCC. CONCLUSION CT is the standard imaging technique for monitoring the effectiveness of TACE and radiofrequency ablation. Contrast-enhanced sonography and MRI can complement CT in evaluating the therapeutic response.

Pre-Treatment Diffusion-Weighted MR Imaging for Predicting Tumor Recurrence in Uterine Cervical Cancer Treated with Concurrent Chemoradiation: Value of Histogram Analysis of Apparent Diffusion Coefficients

Objective To evaluate the value of apparent diffusion coefficient (ADC) histogram analysis for predicting tumor recurrence in patients with uterine cervical cancer treated with chemoradiation therapy (CRT). Materials and Methods Our institutional review board approved this retrospective study and waived informed consent from each patient. Forty-two patients (mean age, 56 ± 14 years) with biopsy-proven uterine cervical squamous cell carcinoma who underwent both pre-treatment pelvic magnetic resonance imaging with a 3.0 T magnetic resonance scanner and concurrent CRT were included. All patients were followed-up for more than 6 months (mean, 36.4 ± 11.9 months; range 9.0-52.8 months) after completion of CRT. Baseline ADC parameters (mean ADC, 25th percentile, 50th percentile, and 75th percentile ADC values) of tumors were calculated and compared between the recurrence and no recurrence groups. Results In the recurrence group, the mean ADC and 75th percentile ADC values of tumors were significantly higher than those of the no recurrence group (p = 0.043 and p = 0.008, respectively). In multivariate analysis, the 75th percentile ADC value of tumors was a significant predictor for tumor recurrence (p = 0.009; hazard ratio, 1.319). When the cut-off value of the 75th percentile ADC (0.936 × 10-3 mm2/sec) was used, the overall recurrence free survival rate above the cut-off value was significantly lower than that below the cut-off value (51.9% vs. 91.7%, p = 0.003, log-rank test). Conclusion Pre-CRT ADC histogram analysis may serve as a biomarker for predicting tumor recurrence in patients with uterine cervical cancer treated with CRT.

Diagnostic performance of 64-section CT using CT gastrography in preoperative T staging of gastric cancer according to 7th edition of AJCC cancer staging manual

ObjectivesTo evaluate the accuracy of 64-section multidetector CT with CT gastrography for determining the depth of mural invasion in patients with gastric cancer according to the 7th edition of the AJCC cancer staging manual.MethodsA total of 127 patients with gastric cancer and who had undergone both esophago-gastro-duodenoscopy and 64-section CT were included in this study. Two radiologists independently reviewed the preoperative CT images with respect to the detectability and T-staging of the gastric cancers. The sensitivity, specificity, accuracy and overall accuracy of each reviewer for the T staging of gastric cancer were calculated.ResultsOverall, gastric cancer was detected in 123 (96.9%) of the 127 cancers on the CT images. Reviewer 1 correctly staged 98 gastric cancers, and reviewer 2 correctly classified 105 gastric cancers. The overall diagnostic accuracy of the T staging was 77.2% (98/127) for reviewer 1 and 82.7% (105/127) for reviewer 2.Conclusion64-section CT using CT gastrography showed a reasonable diagnostic performance for determining the T staging in patients with gastric cancer according to the 7th edition of the AJCC cancer staging manual.Key Points64-section CT is useful for determining the T staging of gastric cancerVirtual gastroscopy is helpful for detecting early gastric cancerNew CT criteria may be applicable to the T stagingThe normal gastric wall frequently shows a multilayered pattern

Radiofrequency Ablation Combined with Transcatheter Arterial Chemoembolization for the Treatment of Single Hepatocellular Carcinoma of 2 to 5 cm in Diameter: Comparison with Surgical Resection

Objective To compare the effectiveness of radiofrequency ablation (RFA) combined with transcatheter arterial chemoembolization (TACE) with surgical resection in patients with a single hepatocellular carcinoma (HCC) ranging from 2 to 5 cm. Materials and Methods The study participants were enrolled over a period of 29 months and were comprised of 37 patients in a combined therapy group and 47 patients in a surgical resection group. RFA was performed the day after TACE, and surgical resection was performed by open laparotomy. The two groups were compared with respect to the length of hospital stay, rates of major complication, and rates of recurrence-free and overall survival. Results Major complications occurred more frequently in the surgical resection group (14.9%) than in the combined therapy group (2.7%). However, there was no statistical significance (p = 0.059). The rates of recurrence-free survival at 1, 2, 3 and 4 years were similar between the combined therapy group (89.2%, 75.2%, 69.4% and 69.4%, respectively) and the surgical resection group (81.8%, 68.5%, 68.5% and 65%, respectively) (p = 0.7962, log-rank test). The overall survival rates at 1, 2, 3 and 4 years were also similar between groups (97.3%, 86.5%, 78.4% and 78.4%, respectively, in the combined therapy group, and 95.7%, 89.4%, 84.3% and 80.3%, respectively, in the surgical resection group) (p = 0.6321, log-rank test). Conclusion When compared with surgical resection for the treatment of a single HCC ranging from 2 to 5 cm, RFA combined with TACE shows similar results in terms of recurrence-free and overall survival rates.

Imaging of Actinomycosis in Various Organs: A Comprehensive Review

Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species. Actinomyces israelii is the organism most commonly found in human disease. Actinomycosis usually manifests with abscess formation, dense fibrosis, and draining sinuses. The disease is further characterized by the tendency to extensively spread beyond normal fascial and connective tissue planes. Actinomycosis occurs most commonly in the cervicofacial region (50%-65%), followed by the thoracic (15%-30%) and abdominopelvic (20%) regions, but rarely involves the central nervous system. Most cases of cervicofacial actinomycosis are odontogenic in origin. In the acute form, cervicofacial disease can manifest with soft-tissue swelling, a painful pyogenic abscess, or a mass lesion. In the subacute to chronic form, a painless indurated mass can spread to the skin, leading to draining sinus tracts. Thoracic manifestations include parenchymal, bronchiectatic, and endobronchial actinomycosis. At computed tomography, pulmonary actinomycosis usually appears as chronic segmental airspace consolidation containing necrotic low-attenuation areas with peripheral enhancement. Abdominopelvic actinomycosis preferentially involves the ileocecal region, ovary, and fallopian tube. The imaging findings favoring abdominopelvic actinomycosis include strong enhancement in the solid portion of the mass after contrast material administration, small rim-enhancing abscesses within the mass, and extensive inflammatory extensions. Actinomycosis in the central nervous system may produce brain abscess, meningitis, subdural empyema, actinomycetoma, and spinal and cranial epidural abscess. In general, actinomycosis responds well to antibiotic therapy, but long-term follow-up after treatment is needed because of frequent relapses.

Paget Disease of the Breast: Mammographic, US, and MR Imaging Findings with Pathologic Correlation

Paget disease is a rare malignancy of the breast characterized by infiltration of the nipple epidermis by adenocarcinoma cells. The clinical features of Paget disease are characteristic and should increase the likelihood of the diagnosis being made. An important point is that more than 90% of cases of Paget disease are associated with an additional underlying breast malignancy. Paget disease is frequently associated with ductal carcinoma in situ (DCIS) in the underlying lactiferous ducts of the nipple-areolar complex; it may even be associated with DCIS or invasive breast cancer elsewhere in the breast, at least 2 cm from the nipple-areolar complex. Nevertheless, mammographic findings may be negative in up to 50% of cases. Magnetic resonance (MR) imaging can be useful in patients with Paget disease for evaluation of the nipple-areolar complex and identification of an additional underlying malignancy in the breast. The appropriate surgical treatment must be carefully selected and individualized on the basis of radiologic findings, especially those obtained with breast MR imaging.

Review of Ovarian Tumors in Children and Adolescents: Radiologic-Pathologic Correlation

The incidence, histologic distribution, and clinical manifestations of ovarian tumors in the pediatric population are distinct from those in adults. Although ovarian neoplasms in childhood and adolescence are rare, the diagnosis should be considered in young girls with abdominal pain and a palpable mass. Differential diagnosis in children and adolescents with ovarian tumors should be conducted on the basis of unique clinical manifestations, elevated serum tumor marker levels, and distinctive imaging findings. Although the clinical manifestations are nonspecific and may overlap, they may assist in diagnosis of some types of ovarian tumors. Children who present with a palpable mass or symptoms of precocious puberty have a high likelihood of malignancy. Many ovarian tumors are associated with abnormal hormonal activity and/or abnormal sexual development. Elevated levels of serum tumor markers, including α-fetoprotein, the beta subunit of human chorionic gonadotropin, and CA-125, raise concern for ovarian malignancies. However, negative tumor markers do not exclude the possibility of malignancy. Identification of imaging features at ultrasonography, computed tomography, and magnetic resonance imaging can help differentiate benign from malignant ovarian tumors and, in turn, plays a crucial role in determining treatment options. At imaging, malignant ovarian tumors usually appear predominantly solid or heterogeneous and are larger than benign tumors. Because surgery is the primary treatment for ovarian tumors, ovarian salvage with fertility preservation and use of a minimally invasive surgical technique are important in children and adolescents.

Ultrasound-Guided Percutaneous Radiofrequency Ablation of Liver Tumors: How We Do It Safely and Completely.

Ultrasound-guided percutaneous radiofrequency (RF) ablation has become one of the most promising local cancer therapies for both resectable and nonresectable hepatic tumors. Although RF ablation is a safe and effective technique for the treatment of liver tumors, the outcome of treatment can be closely related to the location and shape of the tumors. There may be difficulties with RF ablation of tumors that are adjacent to large vessels or extrahepatic heat-vulnerable organs and tumors in the caudate lobe, possibly resulting in major complications or treatment failure. Thus, a number of strategies have been developed to overcome these challenges, which include artificial ascites, needle track ablation, fusion imaging guidance, parallel targeting, bypass targeting, etc. Operators need to use the right strategy in the right situation to avoid the possibility of complications and incomplete thermal tissue destruction; with the right strategy, RF ablation can be performed successfully, even for hepatic tumors in high-risk locations. This article offers technical strategies that can be used to effectively perform RF ablation as well as to minimize possible complications related to the procedure with representative cases and schematic illustrations.

The Role of Three-Dimensional Multidetector CT Gastrography in the Preoperative Imaging of Stomach Cancer: Emphasis on Detection and Localization of the Tumor

Multidetector CT (MDCT) gastrography has been regarded as a promising technique for the preoperative imaging of gastric cancer. It has the ability to produce various three-dimensional (3D) images. Because 3D reconstruction images are more effective and intuitive for recognizing abnormal changes in the gastric folds and subtle mucosal nodularity than two-dimensional images, 3D MDCT gastrography can enhance the detection rate of early gastric cancer, which, in turn, contributes to the improvement of the accuracy of preoperative tumor (T) staging. In addition, shaded surface display and tissue transition projection images provide a global view of the stomach, with the exact location of gastric cancer, which may replace the need for barium studies. In this article, we discuss technical factors in producing high-quality MDCT gastrographic images and present cases demonstrating the usefulness of MDCT gastrography for the detection and T staging of gastric cancer while emphasizing the significance of preoperative localization of gastric cancer in terms of surgical margin.