Dual-energy CT immediately after endovascular stroke intervention: prognostic implications.

PURPOSE: Posttreatment intracerebral hemorrhage (ICH) after recanalization therapy of acute ischemic stroke increases morbidity and mortality. Dual-energy (DE) computed tomography (CT) allows differentiation of blood-brain barrier disruption (BBBD) and ICH. We evaluated the incidence of ICH and BBBD immediately after endovascular recanalization therapy, the correlation between BBBD and final infarction or ICH size, and the prognostic value of postinterventional BBBD. METHODS: Imaging data sets (pretreatment CT, posttreatment DE-CT, and follow-up imaging by CT and/or magnetic resonance imaging) of 60 consecutive patients after endovascular recanalization therapy of acute ischemic stroke were retrospectively analyzed. After material differentiation, areas of increase attenuation in posttreatment DE-CT were correlated to ICH and infarction in follow-up imaging. RESULTS: Areas of hyperattenuation were observed in 80.0 % (48 of 60) of all posttreatment CT. In 10.4 % (5 of 48) of these, hyperattenuating areas matched the hyperdensities on virtual nonenhanced CT and were rated as hemorrhage. The remaining 89.6 % (43 of 48) of scans with hyperattenuating areas demonstrated hyperdensities exclusively on iodine-only images and were rated as BBBD. All suspected ICH on DE-CT were proven in follow-up imaging. There were no false-positive or false-negative findings of ICH in DE-CT. In 98.3 % (59 of 60) of cases, at least small ischemic infarctions were identified in follow-up imaging. No correlation between the extent of BBBD and the final infarct size and/or early ICH size was found. CONCLUSION: BBBD is a frequent finding after endovascular revascularization therapy. DE-CT allows for a reliable differentiation between frequent BBBD and rare ICH immediately after endovascular recanalization therapy.

[Quality report 2011 of the German Society of Interventional Radiology (DeGIR)--part 2. Endovascular treatment of aortic aneurysms (EVAR)]. / Qualitätsreport 2011: Bericht über die Behandlungsqualität minimalinvasiver Methoden--Teil 2. Interventionelle Therapie (EVAR) von Aortenaneurysmen.

PURPOSE: To analyze the quality of treatment for endovascular aortic aneurysm repair using the data of the DeGIR quality management system. MATERIALS AND METHODS: A retrospective analysis of all data registered in the DeGIR quality management system of the year 2011 was performed regarding the treatment quality for endovascular aortic aneurysm repair. Registry of data within this system was voluntary. Quality aims of correct indication, treatment strategy and results were examined. Special interest was directed towards treatment success, complication rates and radiation exposure. RESULTS: Out of 82,881 data sets from the year 2011 overall 1167 cases of EVAR were registered. 12.4% of these cases encompassed emergency treatments. The most frequent indication was an abdominal aneurysm with 85% of cases. The median aortic diameter was 56.5 mm. 253 cases showed an aortic diameter between 50 and 55 mm. Technical success was achieved in 94.6% of all cases including emergency indications for aortic rupture. The overall complication rate of all cases was 4% with 2.5% major complications. Examining only the elective cases a mortality rate of 0.34% was found. EVAR of ruptured aneurysms yielded a mortality rate of 12%. Median dose area product and fluoroscopy time were 10,676.5 cGy × cm2 und 17.32 min respectively. CONCLUSION: Data analysis of the DeGIR quality management system proved a very high technical success rate for the registered cases of endovascular aortic aneurysm repair accompanied by a low complication rate. Improvement of data quality will need further mandatory fields within the software to be implemented. KEY POINTS: The voluntary DeGIR quality management system has reached a high acceptance among radiologists. Endovascular aortic aneurysm repair by radiologists has shown a very high technical success rate and a very low complication rate.

Optimal sequence timing of CT angiography and perfusion CT in patients with stroke.

OBJECTIVE: Standard stroke CT protocols start with non-enhanced CT followed by perfusion-CT (PCT) and end with CTA. We aimed to evaluate the influence of the sequence of PCT and CTA on quantitative perfusion parameters, venous contrast enhancement and examination time to save critical time in the therapeutic window in stroke patients. METHODS AND MATERIALS: Stroke CT data sets of 85 patients, 47 patients with CTA before PCT (group A) and 38 with CTA after PCT (group B) were retrospectively analyzed by two experienced neuroradiologists. Parameter maps of cerebral blood flow, cerebral blood volume, time to peak and mean transit time and contrast enhancements (arterial and venous) were compared. RESULTS: Both readers rated contrast of brain-supplying arteries to be equal in both groups (p=0.55 (intracranial) and p=0.73 (extracranial)) although the extent of venous superimposition of the ICA was rated higher in group B (p=0.04). Quantitative perfusion parameters did not significantly differ between the groups (all p>0.18), while the extent of venous superimposition of the ICA was rated higher in group B (p=0.04). The time to complete the diagnostic CT examination was significantly shorter for group A (p<0.01). CONCLUSION: Performing CTA directly after NECT has no significant effect on PCT parameters and avoids venous preloading in CTA, while examination times were significantly shorter.

[Quality report 2011 of the Germyn Society of Interventional Radiology (DeGIR) - report about treatment quality of minimal invasive procedures]. / DeGIR-Qualitätsreport 2011 - Bericht über die Behandlungsqualität minimalinvasiver Methoden.

In 1994 the German Society of Interventional Radiology (DeGIR) introduced a voluntary quality mangement program. Out of a total of 82 881 of the year 2011, 36 467 patients, who received interventional recanalisation of pelvic or lower extremity arteries were chosen for an in depth analysis. In 33 104 (90.8 %) cases indication for interventional treatment was determined by at least one further discipline or even a multidisciplinary conference. Most treated patients were classified as Fontaine II or higher. Technical success rate over all procedures and regions was 96.2 % showing a very low failure rate of only 3.8 %. The overall complication rate was 3.2 %, periinterventional morbidity (complication C, D or E according to SIR classification) was 1.37 % and periinterventional mortality was 0.07 % (24 cases). X-ray exposure was recorded as well showing an average fluoroscopy time of 12 minutes and a dose-area product of 5034 cG × cm2. The voluntary quality management system was well accepted by the interventional radiologists. The software allows to compare the individual data of a single institution with the pooled data of all 192 participating radiology departments.

Intraoperative computed tomography.

Intraoperative computed tomography (iCT) has gained increasing impact among modern neurosurgical techniques. Multislice CT with a sliding gantry in the OR provides excellent diagnostic image quality in the visualization of vascular lesions as well as bony structures including skull base and spine. Due to short acquisition times and a high spatial and temporal resolution, various modalities such as iCT-angiography, iCT-cerebral perfusion and the integration of intraoperative navigation with automatic re-registration after scanning can be performed. This allows a variety of applications, e.g. intraoperative angiography, intraoperative cerebral perfusion studies, update of cerebral and spinal navigation, stereotactic procedures as well as resection control in tumour surgery. Its versatility promotes its use in a multidisciplinary setting. Radiation exposure is comparable to standard CT systems outside the OR. For neurosurgical purposes, however, new hardware components (e.g. a radiolucent headholder system) had to be developed. Having a different range of applications compared to intraoperative MRI, it is an attractive modality for intraoperative imaging being comparatively easy to install and cost efficient.

[Neurologic emergencies and multislice computed tomography]. / Neurologische Notfälle in der Mehrschichtcomputertomographie.

Modern MSCT with its broad availability and rapid examination times is the preferred modality in the initial evaluation of neurologic emergencies and by its continual development has become more important within recent years. With increased spatial resolution and new post-processing techniques, non-invasive MSCT angiography is seen to increasingly replace diagnostic DSA. Multidetector CTA is a suitable method for the evaluation of intracranial aneurysms, carotid artery stenoses, arterial dissections, as well as cerebral venous and basilar artery thromboses. Multimodal CT (non-enhanced CCT, CTA and perfusion CT) is used more frequently in the assessment of acute stroke patients, it increases the detection rate of early ischemia and is likely to improve the treatment of acute stroke.

Restaging of patients with lymphoma. Comparison of low dose CT (20 mAs) with contrast enhanced diagnostic CT in combined [18F]-FDG PET/CT.

AIM: Assessment of the clinical benefit of i.v. contrast enhanced diagnostic CT (CE-CT) compared to low dose CT with 20 mAs (LD-CT) without contrast medium in combined [(18)F]-FDG PET/CT examinations in restaging of patients with lymphoma. PATIENTS, METHODS: 45 patients with non-Hodgkin lymphoma (n=35) and Hodgkin's disease (n=10) were included into this study. PET, LD-CT and CE-CT were analyzed separately as well as side-by-side. Lymphoma involvement was evaluated separately for seven regions. Indeterminate diagnoses were accepted whenever there was a discrepancy between PET and CT findings. Results for combined reading were calculated by rating indeterminate diagnoses according the suggestions of either CT or PET. Each patient had a clinical follow-up evaluation for >6 months. RESULTS: Region-based evaluation suggested a sensitivity/specificity of 66/93% for LD-CT, 87%/91% for CE-CT, 95%/96% for PET, 94%/99% for PET/LD-CT and 96%/99% for PET/CE-CT. The data for PET/CT were obtained by rating indeterminate results according to the suggestions of PET, which turned out to be superior to CT. Lymphoma staging was changed in two patients using PET/CE-CT as compared to PET/LD-CT. CONCLUSION: Overall, there was no significant difference between PET/LD-CT and PET/CE-CT. However, PET/CE-CT yielded a more precise lesion delineation than PET/LD-CT. This was due to the improved image quality of CE-CT and might lead to a more accurate investigation of lymphoma.

[The diagnostic value of dual-energy CT and 3 Tesla MRI in the diagnosis of German Mardi Gras donuts--where is the mustard, where is the custard and where is the jam?]. / Die diagnostische Wertigkeit von Dual-Energy-CT und 3 Tesla-MRT in der Diagnose von Faschingskrapfen (Berliner Pfannekuchen)--Wo ist die Marmelade, wo der Senf und wo der Pudding?

PURPOSE: As a Mardi Gras joke, the original jam or custard fillings of German Mardi Gras donuts are frequently replaced with mustard which cannot be identified on the outside of the donut. The aim of our study was to evaluate the impact of modern CT and MRI techniques on the diagnostic evaluation of donuts filled with mustard, jam or custard. MATERIALS AND METHODS: 4 commercially available donuts were included in the study. One was filled with custard (PK) and one with jam (MK). Two donuts were specifically prepared and filled with Bavarian mustard (SK1) or extra-hot (SK2) mustard. 3 Tesla MRI was performed with T 2- and T 1-weighted STIR, diffusion and susceptibility-weighted (SWI) sequences. In addition, the donuts underwent dual-energy CT. RESULTS: PK was able to be easily differentiated from the other donuts due to its hyperintensity in the STIR sequences and hypointensity in the T 1-weighted sequences. MK was able to be differentiated from S 1K and S 2K on the basis of its diffusion properties. S 1K demonstrated a pronounced heterogeneity of its matrix, especially in SWI. In CT, PK showed a pronounced hypoattenuation with negative Hounsfield units in contrast to the strongly hyperdense MK, S 1K and S 2K. S 1K and S 2K demonstrated X-ray attenuation considerably dependent on the X-ray energy. CONCLUSION: Donuts filled with jam, custard or mustard can be readily differentiated by modern MRI and CT techniques. Therefore, eating a mustard-filled donut can be reliably avoided.

Dual-energy CT angiography of the lung in patients with suspected pulmonary embolism: initial results.

To evaluate the feasibility of dual-energy CT angiography (CTA) of the lung in patients with suspected pulmonary embolism (PE). 24 patients with suspected PE were examined with a single-acquisition, dual-energy CTA protocol (A-system: 140 kV/65 mAsref, B-system: 80kV/190 mAsref) on a dual-source CT system. Lung perfusion was visualized by color-coding voxels containing iodine and air using dedicated dual-energy postprocessing software. Perfusion defects were classified by two blinded radiologists as being consistent or non-consistent with PE. Subjective image quality of perfusion maps and CTA was rated using a 5-point scale (1: excellent, 5: poor). The reading of a third independent radiologist served as the standard of reference for the diagnosis of PE. In all patients with PE (n=4), perfusion defects classified as being consistent with PE were identified in lung areas affected by PE. Both readers did not record perfusion defects classified as being consistent with PE in any of the patients without PE. Thus, on a per patient basis the sensitivity and specificity for the assessment of PE was 100% for both readers. On a per segment basis the sensitivity and specificity ranged between 60-66.7% and 99.5-99.8%. The interobserver agreement was good (k= 0.81). Perfusion defects rated as non-consistent with PE were most frequently caused by streak artifacts from dense contrast material in the great thoracic vessels. The median score of the image quality of both the perfusion maps and CTA was 2. In conclusion, dual-energy CTA of pulmonary embolism is feasible and allows the assessment of perfusion defects caused by pulmonary embolism. Further optimization of the injection protocol is required to reduce artifacts from dense contrast material.

Deconvolution of bolus-tracking data: a comparison of discretization methods.

Model-free measurement of perfusion from bolus-tracking data requires a discretization of the tracer kinetic model. In this study a classification is provided of existing approaches to discretization, and the accuracy of these methods is compared. Two methods are included which are delay invariant (circulant and time shift) and three methods which are not (volterra, singular and hybrid). Simulations of magnetic resonance imaging (MRI) in the brain are performed for two tissue types (plug flow and compartment) with variable delay and dispersion times, temporal resolution and signal to noise. Simulations were compared to measurements in a patient data set. Both delay-invariant methods are equally accurate, but the circulant method is sensitive to data truncation. Overall volterra produces highest estimates of perfusion, followed by hybrid, singular and delay-invariant methods. Volterra is most accurate except in plug-flow without delay or dispersion, which represents an unrealistic tissue type. Differences between methods vanish when delay or dispersion times increase above the temporal resolution. It is concluded that when negative delays cannot be avoided or when an accurate estimate of left-right perfusion ratios is required, the time shift is the method of choice. When delays are certain to be positive and absolute accuracy is the objective, the volterra method is to be preferred.

Intraprocedural thrombus formation during coil placement in ruptured intracranial aneurysms: treatment with systemic application of the glycoprotein IIb/IIIa antagonist tirofiban.

BACKGROUND AND PURPOSE: When using detachable coils to treat intracranial aneurysms, thromboembolism is the most feared and frequently reported complication during or after endovascular therapy. The purpose of this study was to document the therapeutic effect of tirofiban on patency of the parent vessel, rate of rebleedings, and outcome of the patients in the setting of acute subarachnoidal hemorrhage. METHODS: A patient data base was retrospectively reviewed to identify patients in whom thrombus occurred during endovascular treatment of ruptured cerebral aneurysms within a 34-month period and who were treated with tirofiban. All patients underwent anticoagulation with heparin during endovascular treatment procedures. Sixteen patients (age range, 52.9 +/- 10.7 years; 10 women, 6 men) were identified with intraprocedural thrombus formation. The patency of the parent vessel was assessed in a retrospective analysis blinded to outcome. Eight patients received ventriculostomy and had a follow-up CT. RESULTS: Local nonocclusive thrombus at the coil surface was detected in 5 patients, in all of whom the thrombus was dissolved. In 10 patients, partial or total occlusion of the parent vessel occurred during the intervention; in 8 of these, the vessel was recanalized completely and in 2 drug administration was assisted by mechanical means. In 1 patient, however, the occlusion persisted. No periprocedural rebleedings of the ruptured aneurysm occurred; 3 of 8 ventriculostomies had clinically silent small local bleedings. CONCLUSION: The use of tirofiban in the setting of endovascular treatment of ruptured intracranial aneurysms to dissolve platelet aggregation seems relatively safe and effective.