Jens Altenbernd

Dual-energy-CT of hypervascular liver lesions in patients with HCC: investigation of image quality and sensitivity

ObjectiveTo investigate dual-energy CT of hypervascular liver lesions in patients with HCC.MethodsForty patients with hepatocellular carcinomas were investigated with abdominal dual-energy CT. In each patient unenhanced and contrast-enhanced imaging with arterial und portovenous delay were performed. Hypervascular lesions were documented on arterial phase 80-kVp images, 140-kVp images, and the averaged arterial images by two radiologists. Subjective image quality (5-point scale, from 5 [excellent] to 1 [not interpretable]) was rated on all images.ResultsThe mean number of hypervascular HCC lesions detected was 3.37 ± 1.28 on 80-kVp images (p < 0.05), 1.43 ± 1.13 on 140-kVp images (p < 0.05), and 2.57 ± 1.2 on averaged images. The image quality was 0.3 ± 0.5 for 80-kVp (p < 0.05), 1.6 ± 0.5 for 140-kVp (p < 0.05) and 3.2 ± 0.4 for the averaged images.ConclusionLow-kVp images of dual-energy datasets are more sensitive in detecting hypervascular liver lesions. However, this increase in sensitivity goes along with a decrease in the subjective image quality of low-kVp images.

Treatment response after radioembolisation in patients with hepatocellular carcinoma—An evaluation with dual energy computed-tomography

Purpose The aim of this prospective study was to examine the diagnostic value of dual-energy CT (DECT) in the assessment of response of HCC after radioembolisation (RE). Material and methods 40 HCC patients with 82 measurable target lesions were included in this study. At baseline and follow-up examination target lesions were evaluated with (IU), AASLD and Choi measurement criteria. Disease control was defined as the sum of complete response (CR), partial response (PR), progression disease (PD) and stable disease (SD). Results With Choi and IU more patients were considered than PR and less than PD and SD. According to AASLD more patients were measured as SD and PD than PR. 26/40 patients were classified as PR with IU. In contrast measurements with AASLD in only 8/26 patients were also classified as PR. 6/12 SD patients measured with IU were measured as PD with AASLD. 4/26 patients classified with IU as PR were described as SD with CHOI, 10/14 SD patients measured with CHOI were SD according to IU, the other 4 patients were PR with IU. 2/4 PD patients according to CHOI were SD with IU. Conclusion More patients by IU were classified as SD versus PD and PR versus SD. We attribute this to the more detailed consideration of the HU differences between the virtual native and contrast-enhanced series generated by DECT. Iodine uptake (IU) in HCC measured and visualized with DECT is a promising imaging method for the assessment of treatment response after radioembolisations. Key points —dual energy CT of hypervascular tumors such as HCC allows to quantify contrast enhancement without native imaging. —this can be used to evaluate the therapy response after Radioembolization.

Radiation exposure in perfusion CT of the brain.

Objective This study aimed to show the simulation of the radiation exposure of the brain during perfusion measurements multi-detector-CT. Material and Methods The effective dose and different organ doses were measured with thermoluminescent dosimeters in an Alderson-Rando phantom and compared with the data of a simulation program (CT-Expo V1.6) for varying scan protocols with different tube voltages (in kilovolts) and constant parameters for tube current (270 mAs), scan length (28.8 mm), scan time (40 seconds), slice thickness (24 × 1.2 mm), and number of scans (40) for multi-detector-CT perfusion measurements of the brain. Results The thermoluminescent dosimeter measurements yielded effective doses of 3.8 mSv (80 kV), 8.6 mSv (100 kV), 14.1 mSv (120 kV), and 22.2 mSv (140 kV). These values were in line with the data from the simulation program CT-Expo V1.6. The organ doses varied between 97 and 556 mGy (brain), 10.7 and 80.9 mGy (eye lens), 9.6 and 46 mGy (bone marrow), 1.2 and 6.7 mGy (thyroid gland), and 4.1 to 22.3 mGy (skin). The maximum local skin dose ranged from 355 mGy (80 kV) to 1855 mGy (140 kV) in the directly exposed part of the skin. Conclusions The radiation exposure during perfusion measurements of the brain is strongly dependent on the tube voltage and can vary widely even if the other exposure parameters remain constant. Maximum organ doses up to 556 mGy (brain) can be measured. Even if we never reached local organ doses that can cause a direct radiation injury, the review of the tube voltages implemented by the vendor is mandatory beside the limitation of the scanned area by clinical examination and the reduction of the number of scans. Simulation programs are a valuable tool for dose measurements.

Dual-energy CT of liver metastases in patients with uveal melanoma

Objective To investigate the value of different kVp images of dual-energy CT (DECT) for the detection of liver metastases. Methods 20 Patients with uveal melanoma were investigated with DECT of the liver. In each patient contrast-enhanced DECT imaging with arterial delay was performed. Number and size of metastases were documented on arterial phase 80-kVp images, virtual 120-kVp images and following angiographic images (DSA) as part of hepatic chemoperfusion. Attenuation of metastases and several anatomic regions, subjective (image noise, image quality) and objective (SNR, CNR) parameters were documented. Results The mean number of liver metastases detected was significant higher on 80-kVp images than on virtual 120-kVp/DSA images (5.6 ± 2.1 vs. 4.1 ± 1.8/4.3 ± 1.6); (p < 0.001). All lesions sizes were significant better detected with 80 kVp images than with virtual 120 kVp and DSA-Images (80 kVp vs. 120 kVp: <10 mm: 34 vs. 19, p < 0.05; 10–20 mm:, 33 vs. 25, p < 0.05; >20 mm: 56 vs. 42, p < 0.05/80 kVp vs. DSA: <10 mm: 34 vs. 18 p < 0.05; 10–20 mm: 33 vs. 24, p < 0.05; >20 mm: 56 vs. 41, p < 0.05). Number of detected small lesions <10 mm with 120 kVp compared to DSA-images were significant higher (19 vs. 13; p < 0.05), lesions 10–20 mm and >20 mm were measured statistically equally. Noise, SNR and CNR of 80 kVp images were higher compared to 120 kVp images. Image quality of 120 kVp images was higher compared to 80 kVp images. Conclusion Low-kVp images of DECT datasets are more sensitive in detecting liver metastases of patients with uveal melanoma than virtual 120 kVp- and DSA images.

Dual-energy computed tomography for evaluation of pulmonary nodules with emphasis on metastatic lesions

Background The contrast enhancement of pulmonary nodules is a differential diagnostic criterion which can be helpful in staging investigations. Purpose To investigate the impact of dual-energy computed tomography (DECT) with regards to the evaluation of pulmonary nodules with emphasis on metastatic lesions. Material and Methods DECT scans of the thorax were performed in 70 consecutive patients. Data of the lung were acquired in the arterial and in delayed venous phase. The virtual native and overlay image data based on arterial and delayed venous phase of these lesions were compared using CT density values (HU) within the nodule tested for statistical significance. Results A total of 156 pulmonary lesions ≥5 mm were identified on 70 DECT scans. There were no significant differences between the CT-value measurements in the virtual native images based on the arterial and delayed venous phase (27.9+/–3.9 HU vs.28.1+/–4.2 HU, P = 0.89) and between the CT-value measurements in the overlay images based on the arterial und delayed venous phase (35.5+/–6.8 HU vs. 36.6+/–5.0 HU, P = 0.75). Metastases of colorectal carcinoma (51.4+/–9.4 HU vs. 32.5+/–8.9 HU, P = 0.0001), malignant melanoma (56.1+/–6.4 HU vs. 34.2+/–1.6 HU, P = 0.0045), and thyroid cancer (53.5+/–15.5 HU vs. 15.7+/–4.2 HU, P = 0.001) showed a distinct wash-out, whereas metastases of lung cancer (23.1+/–6.3 HU vs. 58.6+/–4.8 HU, P = 0.001), salivary gland cancer (41.4+/–20.3 HU vs. 65.7+/–15.7 HU, P = 0.023), and sarcoma (56.2+/–7.4 HU vs. 90.2+/–3.4 HU, P = 0.001) had an increased enhancement in the delayed venous phase. Conclusion The contrast enhancement behavior of pulmonary metastases can be evaluated with DECT and depends on the type of the primary malignant tumor.

Transjugular Intrahepatic Portosystemic Shunt in Patients with Portal Hypertension: Patency Depends on Coverage and Interventionalist’s Experience

Background and Aims: Transjugular intrahepatic portosystemic shunt (TIPS) is the treatment of choice in decompensated portal hypertension. TIPS revision due to thrombosis or stenosis increases morbidity and mortality. Our aim was to investigate patient- and procedure-associated risk factors for TIPS-revision. Patients and Methods: We retrospectively evaluated 189 patients who underwent the TIPS procedure. Only patients who required TIPS revision within 1 year (Group I, 34 patients) and patients who did not require re-intervention within the first year (Group II [control group], 54 patients) were included. Results: Out of 88 patients, the majority were male (69.3%) and mean age was 56 ± 11 years. Indications for TIPS were refractory ascites (68%), bleeding (24%), and Budd-Chiari syndrome (8%). The most frequent liver disease was alcohol-induced cirrhosis (60%). Forty-three patients (49%) received bare and 45 patients (51%) covered stents, thus resulting in reduction of hepatic venous pressure gradient (HVPG) from 19.0 to 9.0 mm Hg. When comparing patient- and procedure-related factors, the type of stent (p < 0.01) and interventionalist’s experience (number of performed TIPS implantations per year; p < 0.05) were the only factors affecting the risk of re-intervention due to stent dysfunction, while age, gender, indication, Child-Pugh, and model of end-stage liver disease score, platelet count, pre- and post-HVPG, additional variceal embolization, stent diameter, and number of stents did not significantly differ. Conclusion: Patients undergoing TIPS procedure should be surveilled closely for shunt dysfunction while covered stents and high-level experience are associated with increased patency.

Stellenwert der Dual-Energy-CT bei der Vorbereitung einer SIRT

Zielsetzung: Essentiell für eine technisch erfolgreiche selektive interne Radiotherapie (SIRT) ist die genaue Kenntnis der arteriellen hepatischen Versorgung der Leber sowie die Darstellung möglicher extrahepatischer Shunts. Hierfür wurde in einer prospektiven Studie die Dual-Energy-Computertomographie (DECT) mit der digitalen Subtraktionsangiographie (DSA) zur Darstellung der Oberbaucharterien verglichen.