Radiofrequency Ablation of Lung Metastasis Not Suitable for Surgery: Experience in Siriraj Hospital.

BACKGROUND: Percutaneous image-guided radiofrequency ablation (RFA) is being promoted as a novel technique with low morbidity rate in treatment of inoperable lung tumor either primary lung tumor or metastatic disease. OBJECTIVE: To report our experiences of RFA treated for lung metastasis in Siriraj Hospital and to evaluate the efficacy and complication of RFA. MATERIAL AND METHOD: All patients who underwent RFA for lung metastasis at Siriraj Hospital, between January 2007 and December 2013, were included in the present study. Clinical data, pre-procedure image findings including lesion size, location, post-procedure image findings, complications, and outcome were retrospectively reviewed. RESULTS: Fourteen patients (10 male, 4 female) with 27 lung metastasis were treated with RFA. The ablated lung nodules consist of metastasis from hepatocellular carcinoma (n = 13), colorectal adenocarcinoma (n = 9), insular cell thyroid carcinoma (n = 3), and adenocarcinoma of prostate gland (n = 2). Mean patient age was 50 years (age range 28-67 years). Size of the ablated nodules range from 0.5 to 5.0 cm (median = 1.3 cm). The most common complication was pneumothorax, occurring in 71% (10 of 14 patients). Other complications included surgical site infection, atelectasis, loculated hemothorax, loculated empyema, and bronchopleural fistula, occurred in one patient each. Post-procedure image findings showed complete ablations without local tumor recurrence in 81% (22 of 27 nodules). Local tumor recurrences were seen in 19% (5 of 27 nodules). CONCLUSION: Radiofrequency ablation for lung metastasis can be considered as a relatively safe, effective alternative treatment for lung metastasis. Risk factors that may associate with local recurrence include large size nodules and subpleural location.

Evaluation of standard liver volume in adult Thai population using CT volumetric measurement.

OBJECTIVE: 1) to assess the various existing formulas and the simple, diameter-base equation for calculation of standard liver volume (SLV) in a Thai population, using CT volumetric measurement (CTV) as gold standard. 2) to develop a new formula for calculation of SLV in a Thai population. MATERIAL AND METHOD: Liver volume of 117 patients who underwent abdominal MDCT for various indications was measured, using CTV. Correlation between CTV and calculated liver volume, acquired from the simple, diameter-base equation and six previously reported formulas, were analyzed. The new formula correlating body weight (BW) or body surface area (BSA) to the measured liver volume from CTV were established using regression analysis. RESULTS: All existing formulas offer fair to moderate agreement with the measured liver volume from CTV with intra-class correlation (ICC) ranging from 0.280 to 0.576. BW was found to correlate with the measured liver volume from CTV more closely than BSA, then the new formula based on BW was constructed; 21.127 x BW (kg). However our new formula still has only moderate agreement with measured liver volume from CTV (ICC = 0.598). Liver volume calculated from simple, diameter-base equation offer very strong agreement with the measured liver volume from CTV (ICC = 0.829). CONCLUSION: All formulas based on BW and BSA offer only fair to moderate agreement with measured liver volume CTV, which can lead to high degree error in liver volume estimation. The present study supports that liver volume can be more accurately estimated on CT scan using simple, diameter-based equation. This simple, reproducible method can be used as a good alternative for liver volume calculation. It is particularly useful in case where there is no Digital Imaging and Communications in Medicine (DICOM) data or dedicated 3D software with volumetric measurement application available.

A study of wall thickness of gastric antrum: comparison among normal, benign and malignant gastric conditions on MDCT scan.

OBJECTIVE: To evaluate the normal antral wall thickness on MDCT and to determine the optimal cut-off value for differentiating normal and benign from malignant gastric wall thickening. MATERIAL AND METHOD: MDCT scans of 154 patients, 22 malignancies, 66 benign conditions, and 66 normal findings, whose underwent both gastroscopy and MDCT within 30 days were retrospectively reviewed. The degree of gastric distention, antral wall thickness, pattern of wall thickness, and enhancement, the presence or absence of perigastric fat stranding and perigastric lymphadenopathy were evaluated. ROC curve analysis was used to determine the optimal cut-off value of antral wall thickness to differentiate normal and benign from malignant antral wall thickening. RESULTS: The antral wall thickness in malignancy, benign and normal groups were 16.64 +/- 7.28 mm, 5.265 +/- 2.21 mm, and 5.68 +/- 2.13 mm, respectively. There was statistically significant difference between the normal and malignant group (p < 0.001) as well as benign and malignant group (p < 0.001). Whereas, there was no significant difference between normal and benign group (p = 0.78). By using a 10 mm-cutoff value, the sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) for prediction of gastric malignancy were 81.8%, 97.7%, 97.0%, 85.7%, and 95.5%, respectively. Most gastric malignancies had diffused irregular gastric antral wall thickening (87.7%), heterogeneous enhancement with obliterated normal gastric wall layering (88.1%), perigastric fat stranding (72.7%), and perigastric lymphadenopathy (72.7%). CONCLUSION: Normal antral wall thickness ranges from 1 to 16 mm, depends on degree of antral luminal distention. The authors suggest 10 mm antral wall thickness as the optimal cut-off point for differentiating malignancy and non-malignancy conditions. Moreover the diffuse irregular wall thickening, heterogeneous wall enhancement, presence of perigastric fat stranding and perigastric lymphadenopathy often associate with malignancy. These findings are particularly helpful in interpreting MDCT of patients with inadequate antral luminal distention.

Fatal liver mass rupture in a common-variable-immunodeficiency patient with probable nodular regenerating hyperplasia.

BACKGROUND: Nodular regenerating hyperplasia (NRH) is the most common liver involvement in common variable immunodeficiency (CVID). Most patients are asymptomatic with gradually increasing alkaline phosphatase (ALP) and mildly elevated transaminase enzymes over the years. We report the first case of fatal liver mass rupture in a CVID patient with probable NRH. CASE PRESENTATION: A 24-year-old man was diagnosed with CVID at the age of 1.25 years. Genetic testing revealed a transmembrane activator and calcium-modulator and cyclophilin-ligand interactor (TACI) mutation. He had been receiving intravenous immunoglobulin (IVIg) replacement therapy ever since then. The trough level of serum IgG ranged between 750-1200 mg/dL. However, he still had occasional episodes of lower respiratory tract infection until bronchiectasis developed. At 22 years old, computed tomography (CT) chest and abdomen as an investigation for lung infection revealed incidental findings of numerous nodular arterial-enhancing lesions in the liver and mild splenomegaly suggestive of NRH with portal hypertension. Seven months later, he developed sudden hypotension and tense bloody ascites. Emergency CT angiography of the abdomen showed NRH with intrahepatic hemorrhage and hemoperitoneum. Despite successful gel foam embolization, the patient died from prolonged shock and multiple organ failure. CONCLUSIONS: Although CVID patients with NRH are generally asymptomatic, late complications including portal hypertension, hepatic failure, and hepatic rupture could occur. Therefore, an evaluation of liver function should be included in the regular follow-up of CVID patients.

The value of MDCT scans in differentiation between benign and malignant gallbladder wall thickening.

OBJECTIVE: To evaluate the value of MDCT in differentiation of gallbladder carcinoma from other benign conditions in patients with thickened gallbladder wall. MATERIAL AND METHOD: MDCT of 125 patients, 18 gallbladder carcinomas and 107 other benign conditions were retrospectively reviewed. Various direct and indirect CT findings of benign and malignant gallbladder diseases were evaluated. Differences in CT findings between benign and malignancy were calculated using Chi-square test and odds ratio. Additionally, the wall enhancement pattern was evaluated and categorized into five types, according to the presence of striation, thickness of the outer and inner layers, and degree of enhancement of each layer compared with that of normal liver parenchyma. The diagnostic performance of enhancement pattern analysis on MDCT was analyzed. RESULTS: Five direct and five indirect CT findings including wall irregularity focal wall thickening, discontinuous mucosa, submucosal edema, polypoid mass, direct invasion to adjacent organ, biliary obstruction, regional and paraaortic lymphadenopathy and distant metastasis show significant differences between benign and malignancy. The thickened gallbladder wall with one-layer heterogeneous enhancement (type 1) was significantly associated with malignancy. By using type 1 enhancement pattern as the predictor for malignancy, the sensitivity, specificity, and accuracy of MDCT for detection of malignancy was 78%, 94% and 92%, respectively. CONCLUSION: MDCT is a reliable diagnostic method for differentiating between benign and malignant thickened gallbladder wall. Focal and irregular wall thickening are two direct signs that most associated with malignancy. Moreover, the one-layer heterogeneous enhancement of gallbladder wall is suggestive of malignancy.

Accuracy of multidetector computed tomography cholangiography in evaluation of cause of biliary tract obstruction.

OBJECTIVE: To evaluate accuracy of multidetector computed tomography (MDCT) cholangiography in evaluation of cause of biliary tract obstruction. MATERIAL AND METHOD: MDCT cholangiographs of 50 patients with clinically suspected biliary tract obstruction were retrospectively reconstructed and reviewed. The causes of obstruction identified by MDCT were divided into three groups including calculus, benign stricture, and malignancy. Final diagnosis was based on pathological diagnosis or endoscopic retrograde cholangiopancreatography or follow-up. The MDCT diagnosis and final diagnosis were compared RESULTS: The sensitivity, specificity, positive predictive value, and negative redictive value of MDCT cholangiography for detection of calculus, benign stricture, and malignancy were 91.7-100%, except for sensitivity and positive predictive value for detection of benign stricture, which were 66.7% and 66.7% respectively. CONCLUSION: MDCT cholangiography is a fast, noninvasive technique that offers high diagnostic accuracy in evaluation of cause of biliary tract obstruction.

Hybrid peripheral 3D contrast-enhanced MR angiography of calf and foot vasculature.

OBJECTIVE: The objective of our study was to describe hybrid peripheral (HyPer) 3D contrast-enhanced MR angiography (CE-MRA) using sagittal acquisition with parallel imaging of the calf and foot station. The benefit of a dedicated sagittal 3D CE-MRA acquisition of the calf and foot was evaluated by assessing the degree of venous contamination and its diagnostic quality compared with standard bolus chase 3D CE-MRA alone. MATERIALS AND METHODS: Fifty-three patients (99 legs) were scanned with a 1.5-T MR system equipped with a dedicated bilateral lower extremity phased-array coil. First, high-resolution 3D CE-MRA images of the calves and feet were obtained using two separate sagittal slabs with parallel imaging, with a resulting voxel size of 1.4 x 1.0 x 1.0 mm3. Second, standard bolus chase 3D CE-MRA was performed from the abdomen and pelvis station to the calf-foot station. Images were interpreted by two radiologists. The calf-foot arterial trees were divided into 12 segments. Each segment was characterized as diagnostic or nondiagnostic. The degree of venous contamination was assessed as interfering with the diagnosis or not. Paired Student's t test and Wilcoxon's signed rank test were used to test for statistically significant differences between the techniques. RESULTS: For the left leg (n = 48), the mean number (+/- SD) of diagnosed arterial segments for HyPer 3D CE-MRA was 9.2 +/- 2.3 and for bolus chase 3D CE-MRA, 7.1 +/- 4.2 (p < or = 0.0004). For the right leg (n = 51), the corresponding values were 9.4 +/- 2.2 and 7.6 +/- 3.5 (p < or = 0.0005), respectively. For bolus chase 3D CE-MRA, venous contamination interfered with the diagnosis in 24 of 99 legs, whereas with HyPer 3D CE-MRA, there was no interference. Selective analysis of the dorsalis pedis arteries showed that the number of diagnostic vessels was 62 (62.6%) of 99 for HyPer 3D CE-MRA and 13 (13.1%) of 99 for bolus chase 3D CE-MRA. CONCLUSION: HyPer 3D CE-MRA is an alternative method for time-resolved high-resolution peripheral CE-MRA in evaluating the trifurcation and feet vessels with no venous contamination.

MR and MRCP in the evaluation of primary sclerosing cholangitis: current applications and imaging findings.

Primary sclerosing cholangitis is a progressive cholestatic disease of unknown etiology leading to cirrhosis and liver failure. Several imaging modalities have been used to study this disease, including ultrasonography, computed tomography and hepatobiliary scintigraphy, but accurate diagnosis was found to be best made with endoscopic retrograde cholangiopancreatography or direct cholangiography. However, these 2 methods are invasive and may produce serious complications. Magnetic resonance cholangiopancreatography is a noninvasive imaging technique that has become very useful for diagnosing primary sclerosing cholangitis. Contrast enhanced magnetic resonance imaging provides pertinent information of extraductal abnormalities in addition to biliary ductal changes.

Volumetric measurement of synthetic lung nodules with multi-detector row CT: effect of various image reconstruction parameters and segmentation thresholds on measurement accuracy.

PURPOSE: To evaluate the effect of various multi-detector row computed tomographic (CT) reconstruction parameters and nodule segmentation thresholds on the accuracy of volumetric measurement of synthetic lung nodules. MATERIALS AND METHODS: Synthetic lung nodules of four different diameters (3.2, 4.8, 6.4, and 12.7 mm) were scanned with multi-detector row CT. Images were reconstructed at various section thicknesses (0.75, 1.0, 2.0, 3.0, and 5.0 mm), fields of view (30, 20, and 10 cm), and reconstruction intervals (0.5, 1.0, and 2.0 mm). The nodules were segmented from the simulated background lung region by using four segmentation thresholds (-300, -400, -500, and -600 HU), and their volumes were estimated and compared with a reference standard (measurements according to fluid displacement) by computing the absolute percentage error (APE). APE was regressed against nodule size, and multivariate analysis of variance (MANOVA) was performed with APE as the dependent variable and with four within-subject factors (field of view, reconstruction interval, threshold, and section thickness). RESULTS: The MANOVA demonstrated statistically significant effects for threshold (P = .02), section thickness (P < .01), and interaction of threshold and section thickness (P = .04). The regression of mean APE values on nodule size indicates that APE progressively increases with decreasing synthetic nodule size (R2 = 0.99, P < .01). CONCLUSION: For accurate measurement of lung nodule volume, it is critical to select a section thickness and/or segmentation threshold appropriate for the size of a nodule.