Hans Rigauts

Pulmonary vein varix: diagnosis with multi-slice helical CT

Abstract. The diagnosis of a pulmonary vein varix with a recently introduced new CT technology, multi-slice helical CT, is discussed. The advantage of multi-slice helical CT lies in increased thin-slice coverage during a single breath hold, which is the predominant factor limiting scan time. This CT technique facilitates the diagnosis of vascular pulmonary pathology.

Improved focal liver lesion detection: comparison of single-shot spin-echo echo-planar and superparamagnetic iron oxide (SPIO)-enhanced MRI.

To prospectively compare single‐shot spin‐echo echo‐planar imaging (SSSE‐EPI) using b = 0, 10, 150, and 400 seconds/mm2 with standard MRI techniques after intravenous super paramagnetic iron oxide (SPIO) in the detection and characterization of focal liver lesions with focus on small (<10 mm) focal liver lesions.

Focal liver lesion detection and characterization: Comparison of non-contrast enhanced and SPIO-enhanced diffusion-weighted single-shot spin echo echo planar and turbo spin echo T2-weighted imaging

PURPOSE To compare lesion conspicuity and image quality between single-shot spin echo echo planar imaging (SS SE-EPI) before, immediately and 5min after intravenous (IV) injection of superparamagnetic iron oxide (SPIO) for detecting and characterizing focal liver lesions (FLLs). MATERIALS AND METHODS Twenty-five patients suspected for colorectal liver metastases were prospectively included. Lesion detection and characterization were compared between all SS SE-EPI and T2-weighted turbo spin echo (T2w TSE) sets (two-sided Fishers exact test). Image quality and lesion conspicuity were compared for SS SE-EPI sets using rank order statistic (RIDIT). Reference standard comprised of surgery, biopsy and/or follow-up. RESULTS Reference standard demonstrated 18 benign and 43 malignant FLLs. Best lesion detection (p<0.05) was achieved with non-contrast-enhanced SS SE-EPI. Lesion characterization was best using all T2w TSE sequences. Best image quality and lesion conspicuity (p<0.05) was achieved with non-contrast-enhanced SS SE-EPI. CONCLUSION Non-contrast-enhanced SS SE-EPI was best for lesion detection. SS SE-EPI sequences were not useful for lesion characterization (differentiation between benign and malignant lesions). Unenhanced SS SE-EPI did not allow differentiation especially as many benign FLLs were hyperintense on the highest b-value images. Combining unenhanced and SPIO-enhanced SS SE-EPI performed better but still was not clinically useful due to variable degree of uptake and vascular pooling of SPIO for (especially) benign FLLs. T2w TSE with SPIO-enhancement was needed for characterization.

Prediction of aortoiliac stent graft length: comparison of a semiautomated computed tomography angiography method and calibrated aortography.

Objective The aim of this study is to compare multislice computed tomography (MSCT) in combination with a newly developed semiautomated software program with calibrated aortography in patients who are scheduled for endovascular aortic stent graft placement. Methods From November 2000 until December 2001, seven patients with an abdominal aortic aneurysm (AAA) underwent both calibrated aortography and MSCT for preoperative endovascular stent graft planning. Both studies were performed within 14 days. Further, length measurements were performed with a semiautomated computerized tomographic angiography (CTA) calibration method and a conventional calibrated aortography technique using three differently configured tubes with variable tortuosity. The AAA length measurements of the semiautomated CTA calibration method and the calibrated aortography were compared. Results Statistical analysis included linear regression analysis and revealed a probability value of 0.000381 and an r2 value of 0.93. Using phantoms, it is proven by the authors that the accuracy of the semiautomated CTA calibration method increases with increasing tortuosity when compared with the conventional calibrated aortography technique. Conclusions Our preliminary results show that the semiautomated CTA calibration method has a potentially advantageous role in preoperative stent graft planning regarding the aortic length measurements and seems to be more accurate than calibrated aortography, especially in extremely tortuous vessels. Further studies have to be performed, however.

Perfusion maps of the whole liver based on high temporal and spatial resolution contrast-enhanced MRI (4D THRIVE): Feasibility and initial results in focal liver lesions

PURPOSE To prospectively evaluate a new imaging sequence (4D THRIVE) for whole liver perfusion in high temporal and spatial resolution. Feasibility of parametric mapping and its potential for characterizing focal liver lesions (FLLs) are investigated. MATERIALS AND METHODS Fifteen patients suspected for colorectal liver metastases (LMs) were included. Parametric maps were evaluated qualitatively (ring-enhancement and lesion heterogeneity) and compared to three-phased contrast-enhanced MRI. Quantitative analysis was based on average perfusion values of entire FLLs. Reference standard comprised surgery with histopathology or follow-up imaging. Fishers exact test was used for qualitative and Kruskal-Wallis test for quantitative analysis. RESULTS In total 29 LMs, 17 hemangiomas and 4 focal nodular hyperplasias were evaluated. FLLs could be differentiated by qualitative assessment of parametric maps respectively three-phased contrast-enhanced MRI (Fishers p<0.001 for comparisons between LMs and hemangiomas and LMs and FNHs for both ring-enhancement and lesion heterogeneity) rather than by quantitative analysis of parametric maps (Chi-square for Kep=0.33 (p=0.847) and Chi-square for Kel=1.35 (p=0.509)). CONCLUSION This preliminary study shows potential of 4D THRIVE for whole liver imaging enabling calculation of parametric maps. Qualitative rather than quantitative analysis was accurate for differentiating malignant and benign FLLs.

Prediction and monitoring of treatment effect using T1-weighted dynamic contrast-enhanced magnetic resonance imaging in colorectal liver metastases: Potential of whole tumour ROI and selective ROI analysis

PURPOSE To evaluate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for prediction and early monitoring of treatment in colorectal liver metastases. MATERIALS AND METHODS Ten patients were included. Baseline and follow-up DCE-MRI examinations were evaluated by whole tumour and selected ROI placements calculating Kep-values. Selective ROIs, concentric-like and hot spot, were drawn on early arterial phase images. Monitoring of treatment was performed comparing RECIST1.1 criteria with whole tumour and selected ROI placement. To evaluate treatment effect between responders and non-responders, independent samples t-test was used on Kep-values. RESULTS In each patient largest lesion was evaluated totalling 10 target lesions. At baseline, for whole tumour ROI placements mean Kep-values in responders were significantly higher than mean Kep-values in non-responders (t=7.481, p<0.001). Selective ROI placement comparison of mean Kep-values at baseline and after 6 weeks of treatment (first follow-up measurement) showed significant decrease in responding patients (t=4.706, p=0.003) whereas increase in Kep-values in non-responding patients was not statistically significant. CONCLUSION This preliminary study shows that baseline Kep for whole tumour ROI is a predictor for treatment outcome. Decrease of Kep using selective ROIs allows early identification of response after 6 weeks of treatment.

Traumatic pseudo-aneurysm and dissection of the thoracic aorta in the presence of an aberrant right subclavian artery: value of multi-slice helical CT

Abstract. A case of traumatic pseudo-aneurysm and dissection of the proximal descending thoracic aorta in association with an aberrant right subclavian artery and a common trunk for both common carotid arteries is presented. The diagnosis of this traumatic pseudo-aneurysm and dissection in association with these congenital anomalies by means of a multi-slice helical CT is discussed. To our knowledge, this is the first such case reported in the literature.

Lipiodol-Cisplatin embolisation in hepatocellular carcinoma. Radiological techinique and evaluation

In a 1-year period, 14 patients with inoperable, biopsy-proven hepatocellular cacinoma (HCC) underwent 18 superselective catheterisations of the proper hepatic artery with combined injection of Cisplatin and Liodol. According to Okuda et al. [1], patients were classified into clinical Stages I (2), II (7) and III (5). All 5 Stage III patients died during follow-up. Distal superselective catheterisation of the proper hepatic artery, in order to avoid Lipiodol embolism to the gastroduodenal, gastric or other anastomotic arteries was possible with conventional diagnostic catheters use and inexpensive coaxial (5 cases) or, an easry-to-use an inexpensive coaxial catheterisation system (13 cases). Radiological follow-up was by means of computed tomography (CT) 24 h and 6 weeks after chemoembolisation. Further CT studies were performed depending on the patients progress. Twelve patients had CT follow-up over at least 6 weeks. Hypervascular hepatocellular carcinomas tend to diminish in volume, especially those which retain Lipiodol after 6 weeks, and survival after intra-arterial chemotheraphy is shorter in patients with hypovascular tumours which do not retain Lipiodol. We have treated only a limited number of patients, but consider chemoembolisation okf inoperable HCC with Lipiodol and Cisplatin as useful treatment for Okuda Stage 1 and II patients, but not for those in Stage III. Hypervascularity and Lipiodol retention on follow-up CT could indicate a favourable prognosis.

Addison's disease due to bilateral post-traumatic adrenal haemorrhage: CT and MR findings

In a patient with Addisons disease, who gave a history of a severe car accident, CT showed bilateral enlargement of the adrenal glands. MRI, by demonstrating paramagnetic T1 shortening due to methaemoglobin and haesmosiderin on T2-weighted images, confirmed the haemorrhagic nature of the lesions.