Impact of Vaccination Status on Outcome of Patients With COVID-19 and Acute Ischemic Stroke Undergoing Mechanical Thrombectomy.

BACKGROUND: Data on impact of COVID-19 vaccination and outcomes of patients with COVID-19 and acute ischemic stroke undergoing mechanical thrombectomy are scarce. Addressing this subject, we report our multicenter experience. METHODS AND RESULTS: This was a retrospective analysis of patients with COVID-19 and known vaccination status treated with mechanical thrombectomy for acute ischemic stroke at 20 tertiary care centers between January 2020 and January 2023. Baseline demographics, angiographic outcome, and clinical outcome evaluated by the modified Rankin Scale score at discharge were noted. A multivariate analysis was conducted to test whether these variables were associated with an unfavorable outcome, defined as modified Rankin Scale score >3. A total of 137 patients with acute ischemic stroke (48 vaccinated and 89 unvaccinated) with acute or subsided COVID-19 infection who underwent mechanical thrombectomy attributable to vessel occlusion were included in the study. Angiographic outcomes between vaccinated and unvaccinated patients were similar (modified Thrombolysis in Cerebral Infarction ≥2b: 85.4% in vaccinated patients versus 86.5% in unvaccinated patients; P=0.859). The rate of functional independence (modified Rankin Scale score, ≤2) was 23.3% in the vaccinated group and 20.9% in the unvaccinated group (P=0.763). The mortality rate was 30% in both groups. In the multivariable analysis, vaccination status was not a significant predictor for an unfavorable outcome (P=0.957). However, acute COVID-19 infection remained significant (odds ratio, 1.197 [95% CI, 1.007-1.417]; P=0.041). CONCLUSIONS: Our study demonstrated no impact of COVID-19 vaccination on angiographic or clinical outcome of COVID-19-positive patients with acute ischemic stroke undergoing mechanical thrombectomy, whereas worsening attributable to COVID-19 was confirmed.

Results of interventional treatment of peripheral slow-flow malformations.

BACKGROUND: In recent years sclerotherapy has increasingly become the treatment of choice for peripheral slow-flow malformations. However, the long-term effectiveness of sclerotherapy is still a matter of debate, especially when it comes to new sclerosing agents like polidocanol. This study aims at gathering further information concerning its long-term effectiveness and safety. RESULTS: Most patients reported a reduction of symptoms which include pain (57,7%), swelling (65,4%) and functional impairment (60%). Cosmetic complaints were less likely to be reduced by sclerotherapy (44,4%). In most cases a relief of symptoms was stable for many years, especially after several consecutive treatment sessions. Complication rates were comparably low, with only 2 patients requiring additional treatment at hospital and no lasting damages. (…) (7) Most patients (70,9%) were at least partially satisfied with the treatment. Satisfaction was closely linked to a partial or complete relief of symptoms (p = 0.001). CONCLUSION: Sclerotherapy is a promising way of treating slow-flow-malformations. Polidocanol has proved to be a save sclerosing agent. The reduction of major symptoms was substantial in most cases and lasted for many years.

The DERIVO®2 Embolization Device in the treatment of ruptured and unruptured intracranial aneurysms: A multicenter analysis.

BACKGROUND: Flow diverters are an increasingly used treatment option for intracranial aneurysms. A recent addition to the European market is the DERIVO®2 Embolization Device (DED2), promising improved radiopacity. We aimed to assess the safety and efficacy of the DED2 regarding angiographic and clinical outcomes in ruptured and unruptured cerebral aneurysms. METHODS: We performed a multicenter trial at six interventional centers. Data were prospectively collected and all patients treated with the DED2 were included. The primary endpoint was angiographic aneurysm occlusion at 6 months as assessed by the O'Kelly Marotta (OKM) grading scale with a favorable outcome definition of OKM C + D. Clinical outcome was evaluated according to the modified Rankin scale (mRS). RESULTS: Between August 2020 and July 2021, 37 patients were treated with the DED2 and were included in our analysis. Five patients presented with ruptured aneurysms. Median age was 60 years, 27 patients were female, and 10 male. Median mRS was 0 (range 0-4). Mean aneurysm size was 8.9 ± 7.1 mm with a mean neck size of 6.5 ± 6.1. The DED2 fully opened at deployment in all cases. Clinical follow-up was available for 30 patients (81%). Twenty-five (83%) had an mRS of 0 or 1. Three patients with ruptured aneurysms died during the follow-up period. No treatment-related major morbidity was observed. Follow-up imaging was available in 27 (90%) patients, with 23 patients (85%) showing satisfactory aneurysm occlusion OKM grade C-D. CONCLUSION: In this small cohort, the DED2 provided safe and effective treatment of ruptured and unruptured intracranial aneurysms.

Predictors of Symptomatic Intracranial Hemorrhage after Endovascular Thrombectomy in Acute Ischemic Stroke Patients with Anterior Large Vessel Occlusion-Procedure Time and Reperfusion Quality Determine.

PURPOSE: We aimed to evaluate predictors of symptomatic intracranial hemorrhage (sICH) in acute ischemic stroke (AIS) patients following thrombectomy due to anterior large vessel occlusion (LVO). METHODS: Data on stroke patients from January 2018 to December 2020 in a tertiary care centre were retrospectively analysed. sICH was defined as intracranial hemorrhage associated with a deterioration of at least four points in the National Institutes of Health Stroke Scale (NIHSS) score or hemorrhage leading to death. A smoothed ridge regression model was run to analyse the impact of 15 variables on their association with sICH. RESULTS: Of the 174 patients (median age 77, 41.4% male), sICH was present in 18 patients. Short procedure time from groin puncture to reperfusion (per 10 min OR 1.24; 95% CI 1.071-1.435; p = 0.004) and complete reperfusion (TICI 3) (OR 0.035; 95% CI 0.003-0.378; p = 0.005) were significantly associated with a lower risk of sICH. On the contrary, successful reperfusion (TICI 3 and TICI 2b) was not associated with a lower risk of sICH (OR 0.508; 95% CI 0.131-1.975, p = 0.325). Neither the total time from symptom onset to reperfusion nor the intravenous thrombolysis was a predictor of sICH (per 10 min OR 1.0; 95% CI 0.998-1.001, p = 0.745) (OR 1.305; 95% CI 0.338-5.041, p = 0.697). CONCLUSION: Our findings addressed the paramount importance of short procedure time and complete reperfusion to minimize sICH risk. The total ischemic time from onset to reperfusion was not a predictor of sICH.

When Can an Emergency CTA Be Dispensed with for TIA Patients?

BACKGROUND: Transient ischemic attacks (TIAs) and minor strokes are often precursors of a major stroke. Therefore, diagnostic work-up of the TIA is essential to reduce the patient's risk of further ischemic events. PURPOSE: With the help of this retrospective study, we aim to determine for which TIA patients a CT angiography (CTA) is not immediately necessary in order to reduce radiation exposure and nephrotoxicity. MATERIAL AND METHODS: Clinical and imaging data from patients who presented as an emergency case with a suspected diagnosis of TIA at a teaching hospital between January 2016 and December 2021 were evaluated. The included 1526 patients were divided into two groups-group 1, with major pathologic vascular findings in the CTA, and group 2, with minor vascular pathologies. RESULTS: Out of 1821 patients with suspected TIA on admission, 1526 met the inclusion criteria. In total, 336 (22%) had major vascular pathologies on CTA, and 1190 (78%) were unremarkable. The majority of patients with major vascular pathologies were male and had a history of arterial hypertension, coronary heart disease, myocardial infarction, ischemic stroke, TIA, atherosclerotic peripheral vascular disease, smoking, antiplatelet medication, had a lower duration of TIA symptoms, and had lower ABCD2 scores. CONCLUSIONS: We were able to demonstrate a direct correlation between major CTA pathologies and a history of smoking, age, hyperlipidemia, history of peripheral arterial disease, and a history of stroke and TIA. We were able to prove that the ABCD2 score is even reciprocal to CTA pathology. This means that TIA patients without described risk factors do not immediately require a CTA and could be clarified in the course of treatment with ultrasound or MRI.

CT and DSA for evaluation of spontaneous intracerebral lobar bleedings.

Purpose: This study retrospectively examined the extent to which computed tomography angiography (CTA) and digital subtraction angiography (DSA) can help identify the cause of lobar intracerebral bleeding. Materials and methods: In the period from 2002 to 2020, data from patients who were >18 years at a university and an academic teaching hospital with lobar intracerebral bleeding were evaluated retrospectively. The CTA DSA data were reviewed separately by two neuroradiologists, and differences in opinion were resolved by consensus after discussion. A positive finding was defined as an underlying vascular etiology of lobar bleeding. Results: The data of 412 patients were retrospectively investigated. DSA detected a macrovascular cause of bleeding in 125/412 patients (33%). In total, sixty patients had AVMs (15%), 30 patients with aneurysms (7%), 12 patients with vasculitis (3%), and 23 patients with dural fistulas (6%). The sensitivity, specificity, positive and negative predictive values, and accuracy of CTA compared with DSA were 93, 97, 100, and 97%. There were false-negative CTA readings for two AVMs and one dural fistula. Conclusion: The DSA is still the gold standard diagnostic modality for detecting macrovascular causes of ICH; however, most patients with lobar ICH can be investigated first with CTA, and the cause of bleeding can be found. Our results showed higher sensitivity and specificity than those of other CTA studies.

Mechanical thrombectomy for acute ischemic stroke in COVID-19 patients: multicenter experience in 111 cases.

BACKGROUND: Data on the frequency and outcome of mechanical thrombectomy (MT) for large vessel occlusion (LVO) in patients with COVID-19 is limited. Addressing this subject, we report our multicenter experience. METHODS: A retrospective cohort study was performed of consecutive acute stroke patients with COVID-19 infection treated with MT at 26 tertiary care centers between January 2020 and November 2021. Baseline demographics, angiographic outcome and clinical outcome evaluated by the modified Rankin Scale (mRS) at discharge and 90 days were noted. RESULTS: We identified 111 out of 11 365 (1%) patients with acute or subsided COVID-19 infection who underwent MT due to LVO. Cardioembolic events were the most common etiology for LVO (38.7%). Median baseline National Institutes of Health Stroke Scale score and Alberta Stroke Program Early CT Score were 16 (IQR 11.5-20) and 9 (IQR 7-10), respectively. Successful reperfusion (mTICI ≥2b) was achieved in 97/111 (87.4%) patients and 46/111 (41.4%) patients were reperfused completely. The procedure-related complication rate was 12.6% (14/111). Functional independence was achieved in 20/108 (18.5%) patients at discharge and 14/66 (21.2%) at 90 days follow-up. The in-hospital mortality rate was 30.6% (33/108). In the subgroup analysis, patients with severe acute COVID-19 infection requiring intubation had a mortality rate twice as high as patients with mild or moderate acute COVID-19 infection. Acute respiratory failure requiring ventilation and time interval from symptom onset to groin puncture were independent predictors for an unfavorable outcome in a logistic regression analysis. CONCLUSION: Our study showed a poor clinical outcome and high mortality, especially in patients with severe acute COVID-19 infection undergoing MT due to LVO.

Thrombectomy of symptomatic isolated occlusions of posterior cerebral arteries in segment P1 and P2 in acute stroke treatment.

BACKGROUND: Interventional stroke treatments for occlusions of the posterior circulation are established procedures. However, there are limited data on the treatment of isolated symptomatic P1 and P2 occlusions, which we have examined in this study. PURPOSE: To investigate the mechanical thrombectomy of distal posterior occlusions. MATERIAL AND METHODS: Retrospectively, data from patients with isolated P1 and P2 occlusions treated with MT were evaluated. Successful reperfusions have been defined as modified thrombolysis in cerebral infarct (mTICI) Grade 2b-3. A good clinical outcome was defined as a 90-day modified Rankin score 0-2. RESULTS: All 79 treated patients were primarily aspirated. Stent retrievers were used secondarily in nine patients. Successful reperfusion was achieved in 95% of patients. Of the patients, 57% had a favorable clinical outcome after 90 days. CONCLUSION: Mechanical thrombectomy with first line aspiration of symptomatic P1 and P2 occlusions is a safe and effective procedure.

Cardiac Imaging Within Emergency CT Angiography for Acute Stroke Can Detect Atrial Clots.

Cardiac embolism is presumed to cause a significant portion of cryptogenic strokes. Transesophageal echocardiography may detect intracardiac thrombi, but this remains a rare finding, possibly because remnant clots dissolve spontaneously or following thrombolysis. Cardiac imaging within cerebral CT angiography might offer an alternative method for thrombus detection within hyperacute stroke assessment. In a proof-of-concept study we analyzed records of patients aged ≥ 60 years that presented with suspected stroke and underwent extended cerebral CT angiography as part of their emergency assessment. CT imaging of patients with ischemic stroke or transient ischemic attack (TIA) and atrial fibrillation and of those with embolic strokes of undetermined source (ESUS) was reviewed for intracardiac clots and other cardiac or aortic pathology. Over a period of 3 months 59 patients underwent extended CT angiography for suspected stroke, 44 of whom received a final diagnosis of ischemic stroke or TIA. Of those, 17 had atrial fibrillation, and four fulfilled ESUS criteria. Thrombi were detected within atrial structures on CT angiography in three cases. In two ESUS patients complex atheromatosis of the proximal ascending aorta with irregular and ulcerating plaques was detected. Cardiac imaging within emergency cerebral CT angiography is feasible and can provide valuable diagnostic information in a patient group that might not routinely undergo transesophageal echocardiography. A small change to emergency assessment could potentially uncover cardioembolic pathology in cases that would have remained cryptogenic otherwise.

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.

Frontline ADAPT therapy to treat patients with symptomatic M2 and M3 occlusions in acute ischemic stroke: initial experience with the Penumbra ACE and 3MAX reperfusion system.

BACKGROUND: After a series of positive studies for mechanical thrombectomy in large vessel occlusion acute ischemic stroke, the question remains, can symptomatic patients with distal vessel occlusion benefit from mechanical thrombectomy? PURPOSE: To assess the safety and efficacy of the 3MAX reperfusion system as frontline therapy for M2 and M3 occlusions. METHODS: This study retrospectively collected data on 58 patients treated for M2 and M3 occlusions between January and September 2016. Of these 58 patients, 31 had an isolated M2 or M3 occlusion. Eligible patients were treated with 3MAX by adirect first pass aspiration (ADAPT) technique within 6 hours following stroke onset. Effectiveness was defined by functional independence (90-day modified Rankin Scale core 0-2) and revascularization to modified Thrombolysis in Cerebral Infarction (mTICI) 2b-3 scores adjudicated by a core laboratory, while complication rates were used to determine safety of the device and the procedure. RESULTS: Patients with an isolated M2 or M3 occlusion had a mean age of 68.6±13.3 years (range 18-90 years), a median National Institutes of Health Stroke Score of 15 (IQR 9-19), and ASPECTS score of 9 (IQR 8-10). After intervention, 100% (31/31) of patients were revascularized to mTICI 2b-3; 77.4% (24/31) of patients showed revascularization to mTICI 3. Aspiration alone led to revascularization in 83.9% (26/31) of patients. At 90 days, 96.8% (30/31) of patients had achieved functional independence. The incidence of symptomatic intracranial hemorrhage was 0% (0/31). CONCLUSIONS: Results suggest that the 3MAX reperfusion system is safe and effective in achieving successful revascularization and functional independence for patients with acute ischemic stroke secondary to M2 and M3 occlusions using ADAPT, either as frontline monotherapy, or in combination with adjunctive devices.

Improved Image Quality and Detectability of Hypovascular Liver Metastases on DECT with Different Adjusted Window Settings.

Objective To investigate dual-energy CT of hypovascular liver metastases (LMs) with special focus on window settings (WSs). The aim of the study is to investigate the extent to which adapted WSs and the low-energy images of DECT improve the visibility especially of smaller LMs. Materials and Methods 30 patients with LMs of colorectal cancer were investigated with DECT of the liver. In each patient contrast-enhanced DECT imaging with portal-venous delay was performed. The total number, mean number and conspicuity (1 = excellent - 5 = poor) of LMs were documented on 80-kVp images and virtual 120-kVp images with different WSs (25/200 HU, 50/200, 75/200 HU, 25/350 HU, 50/350 HU, 75/350 HU, 25/500 HU, 50/500 HU, 75/500 HU). The attenuation (HU) of LMs and several anatomic regions and the background noise on 80 kVp images and virtual 120 kVp images were documented. Signal (liver)/noise and liver/LM ratio (SNR/LLMR) were calculated. The total number of LMs depending on size (< 1 cm, 1 - 2 cm, > 2 cm) on 80 kVp images and virtual 120 kVp images with previously investigated best and regular WSs were documented. Results The highest total number, mean number per patient and total number of LMs < 1 cm were detected with the WS 25/350 HU on 80kVp images (7.0; p = 0.02/218; p = 0.01/64;p < 0.001) compared to the WS 75/200 HU on virtual 120 kVp images and the regular WS 50/350 HU on 80 kVp images and virtual 120 kVp images. The best conspicuity of LMs on 80 kVp images was documented with the WS 25/350 HU compared to the best WS on virtual 120 kVp images with 75/200 HU (1.2 vs. 2.5; p = 0.01). HU of normal liver, aorta, SNR and LLMR differed significantly between 80 kVp images and virtual 120 kVp images (128.1 vs. 93.6; < 0.05/192.8 vs. 131.4; < 0.05/10.3 vs. 8.1; p < 0.05/2.8 vs. 2.1; p < 0.05). Conclusion Low kVp images of DECT datasets are more precise in detecting hypovascular liver metastases than virtual 120 kVp images. Dedicated window settings have a relevant influence on conspicuity. Key points: · DECT is a promising tool for detecting hypovascular liver metastases.. · The diagnostic value of low kVp image data can be significantly increased by using special window settings.. · Use of only the low kVp images would lead to reduced radiation exposure.. Citation Format · Altenbernd Jens, Forsting Michael, Lauenstein Thomas et al. Improved Image Quality and Detectability of Hypovascular Liver Metastases on DECT with Different Adjusted Window Settings. Fortschr Röntgenstr 2017; 189: 228 - 232.

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.

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.

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.

Impact of dual-energy CT prior to radioembolization (RE).

BACKGROUND: Depiction of the exact arterial liver anatomy as well as identifying potential extrahepatic non-target vessels is crucial for a successful preparation of radioembolization (RE). PURPOSE: To compare the diagnostic impact of dual-energy computed tomography (DECT) to digital subtraction angiography prior to RE. MATERIAL AND METHODS: DECT was applied in 46 patients with hepatocellular carcinoma (HCC) prior to RE. Eighty kV DE as well as reconstructed 120 kV equivalent DE datasets were evaluated in comparison to correlating digital subtraction angiography (DSA) datasets. Two radiologists evaluated in consensus the delineation of liver arteries and extrahepatic non-target vessels utilizing a 4-point scale (4 = excellent delineation; 1 = non-diagnostic). In addition, the arterial vascularization of liver segment IV was evaluated and classified: signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR; liver arteries to adjacent liver tissue) were obtained via ROI analysis. RESULTS: Both imaging techniques (DECT, DSA) enabled high-quality assessment of all analyzed liver arteries. Out of the two CT datasets, 80 kVp-DE datasets offered superior delineation of the right gastric artery (3.5 ± 0.7 vs. 2.5 ± 0.5), the vascularization of segment IV (3.9 ± 0.2 vs. 3.3 ± 0.5) as well as potential extrahepatic non-target vessels (3.9 ± 0.1 vs. 3.3 ± 0.5). In accordance to the results of the qualitative analysis, 80 kVp-DE datasets also yielded higher SNR (34.84 vs. 29.31) and CNR (28.29 vs. 21.8) values in comparison to the 120 kVp datasets. CONCLUSION: Eighty kVp DECT enables a significantly better assessment of the arteries of the upper abdomen for therapy planning in comparison to correlating 120 kVp datasets. This may allow for identification of potential extrahepatic non-target vessels and assessment of target volume for therapy planning prior to DSA.

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.

Evaluation of the PET component of simultaneous [(18)F]choline PET/MRI in prostate cancer: comparison with [(18)F]choline PET/CT.

PURPOSE: The aim of this study was to evaluate the positron emission tomography (PET) component of [(18)F]choline PET/MRI and compare it with the PET component of [(18)F]choline PET/CT in patients with histologically proven prostate cancer and suspected recurrent prostate cancer. METHODS: Thirty-six patients were examined with simultaneous [(18)F]choline PET/MRI following combined [(18)F]choline PET/CT. Fifty-eight PET-positive lesions in PET/CT and PET/MRI were evaluated by measuring the maximum and mean standardized uptake values (SUVmax and SUVmean) using volume of interest (VOI) analysis. A scoring system was applied to determine the quality of the PET images of both PET/CT and PET/MRI. Agreement between PET/CT and PET/MRI regarding SUVmax and SUVmean was tested using Pearson's product-moment correlation and Bland-Altman analysis. RESULTS: All PET-positive lesions that were visible on PET/CT were also detectable on PET/MRI. The quality of the PET images was comparable in both groups. Median SUVmax and SUVmean of all lesions were significantly lower in PET/MRI than in PET/CT (5.2 vs 6.1, p<0.05 and 2.0 vs 2.6, p<0.001, respectively). Pearson's product-moment correlation indicated highly significant correlations between SUVmax of PET/CT and PET/MRI (R=0.86, p<0.001) as well as between SUVmean of PET/CT and PET/MRI (R=0.81, p<0.001). Bland-Altman analysis revealed lower and upper limits of agreement of -2.77 to 3.64 between SUVmax of PET/CT vs PET/MRI and -1.12 to +2.23 between SUVmean of PET/CT vs PET/MRI. CONCLUSION: PET image quality of PET/MRI was comparable to that of PET/CT. A highly significant correlation between SUVmax and SUVmean was found. Both SUVmax and SUVmean were significantly lower in [(18)F]choline PET/MRI than in [(18)F]choline PET/CT. Differences of SUVmax and SUVmean might be caused by different techniques of attenuation correction. Furthermore, differences in biodistribution and biokinetics of [(18)F]choline between the subsequent examinations and in the respective organ systems have to be taken into account.

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

OBJECTIVE: To investigate dual-energy CT of hypervascular liver lesions in patients with HCC. METHODS: Forty 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. RESULTS: The 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. CONCLUSION: Low-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.

Impermeability to blood of the E-vita open plus hybrid stent-graft: experimental and clinical evaluation.

PURPOSE: To evaluate the impermeability to blood of the modified E-vita open plus hybrid stent-graft in animal experiments and initial clinical applications in the replacement of the ascending aorta and aortic arch combined with antegrade stent-grafting of the descending aorta. METHODS: In 3 acute pig experiments, a tightly woven hybrid stent-graft (18 x 50-mm) was implanted in the descending aorta. Blood loss was measured after clamp release in fully heparinized animals by wrapping the aortic segment in a polyethylene bag. For histological examination, 12-mm-diameter stent-grafts were interposed in the abdominal aorta of 6 minipigs. The animals were sacrificed and studied after 3, 6, and 9 weeks. Between October 2008 and October 2009, 9 patients were treated for 6 type I dissections and 3 thoracic aortic aneurysms using the new prosthesis. Blood loss and blood replacement were evaluated. RESULTS: Mean blood loss under heparinization was 35+/-4 mL/min in the animal model. Histological examination of the explanted grafts demonstrated buildup of neointima. In the clinical cases, the mean blood loss within the first 24 hours was 489 mL; no re-exploration for bleeding was required. During a 6-month follow-up, no thrombus formation was seen within the vascular graft and no embolic event occurred. CONCLUSION: The new low-porosity hybrid prosthesis proved to be absolutely tight in animal experiments; histological examination demonstrated endothelial cell ingrowth with a trend to hyperplasia in this small-diameter graft. These results were confirmed in the clinical cases by the extremely minimal blood loss and an uneventful course.