Endoscopic neo-anastomosis by Rendez-vous technique for the treatment of complete occlusion of bilioenteric anastomoses and distal bile ducts (case series).

BACKGROUND AND AIMS: The complete occlusion of bilioenteric anastomoses is a rare and challenging clinical condition. Repeated surgery is burdened with technical difficulties and significant morbidity. We report the first series of completely occluded bilioenteric anastomoses resp. distal bile duct successfully treated by simultaneous percutaneous and retrograde endoscopic interventions. PATIENTS AND METHODS: This case series includes 4 patients with obstructive jaundice and/or recurring cholangitis and pain due to complete fibrotic occlusion of a hepaticojejunostomy (3 patients) and the distal bile duct (1 patient). After performing PTCD and stepwise dilation of the biliocutaneous tract, we tried to approach the occluded anastomosis from 2 sides by simultaneous percutaneous cholangioscopy and peroral device-assisted enteroscopy/duodenoscopy. By cutting through the separating tissue layer with a needle knife under endoscopic and fluoroscopic control using diaphanoscopy, a new anastomosis should be established followed by dilation of the neoanastomosis with subsequent percutaneous transhepatic drainage for a minimum of 1 year to prevent re-occlusion. RESULTS: The Rendez-vous maneuver was successful in 3/4 cases. In one case, the retrograde access to the anastomosis failed, so the neoanastomosis was cut under cholangioscopic and fluoroscopic guidance only. The neoanastomosis could be established successfully in all 4 cases. Jaundice, cholangitis, and pain disappeared. Minor periinterventional adverse events were cholangitis (n = 1) and pneumonia (n = 1) due to aspiration, which could be managed conservatively. No serious adverse events were observed, and no re-occlusion of any neoanastomosis occurred during the follow-up before and after removal of the percutaneous drainage. CONCLUSION: Simultaneous percutaneous cholangioscopy and device-assisted enteroscopy/duodenoscopy with endoscopic creation of a neoanastomosis is a possible concept for the treatment of completely occluded bilioenteric anastomoses and distal bile ducts. This case series confirms the feasibility, safety, and long-term effectiveness of this treatment.

The postsurgical pancreas. / Das postoperative Pankreas.

BACKGROUND: Partial pancreatic resections are among the most complex surgical procedures in visceral tumor medicine and are associated with a high postoperative morbidity with a complication rate of 40-50 % of patients even in specialized centers. METHODS: Description of typical surgical resection procedures and the resulting postoperative anatomy, typical normal postoperative findings, common postoperative complications, and radiological findings. RESULTS AND CONCLUSION: CT is the most appropriate imaging technique for rapid and standardized visualization of postoperative anatomy and detection of clinically suspected complications after partial pancreatic resections. The most common complications are delayed gastric emptying, pancreatic fistula, acute pancreatitis, bile leakage, abscess, and hemorrhage. Radiologists must identify the typical surgical procedures, the postoperative anatomy, and normal postoperative findings as well as possible postoperative complications and know interventional treatment methods for common complications. KEY POINTS: · Morbidity after pancreatic surgery remains high.. · CT is the best method for visualizing postoperative anatomy and is used for early detection of complications.. · Pancreatic fistula is the most common relevant complication after pancreatic resection.. · The ability of a center to manage complications is crucial to ensure the success of therapy.. CITATION FORMAT: · Fischbach R, Peller M, Perez D et al. The postsurgical pancreas. Fortschr Röntgenstr 2024; DOI: 10.1055/a-2254-5824.

Long-Term Follow-up and Mortality Rate of Patients of the Randomized Freeway Stent Study.

PURPOSE: This follow-up study was designed as a reopen of the completed Freeway Stent Study and collected mortality and clinical outcome data for at least 5 years after enrollment to evaluate long-term patient safety and treatment efficacy. The primary study enrolled 204 patients with stenosis or occlusion in the superficial femoral artery and proximal popliteal artery. Patients were randomized to primary nitinol stenting followed by standard PTA or primary nitinol stenting followed by FREEWAY™ paclitaxel-eluting balloon PTA. METHODS: Previous patients were recontacted by phone or during a routine hospital visit, and medical records were reviewed. Vital and clinical status information was collected. RESULTS: No increased late mortality was observed at 5 years, with an all-cause mortality rate of 12.0% in the FREEWAY drug-eluting balloon group versus 15.0% in the non-paclitaxel PTA group. No accumulation of any cause of death was observed in either group, nor was there any correlation with the dose of paclitaxel used. Freedom from clinically driven target lesion revascularization at 5 years was significantly higher in the FREEWAY drug eluting balloon group (85.3%) compared to standard PTA group (72.7%) Log-rank p = 0.032. CONCLUSION: The safety results presented support the recent conclusions that the use of paclitaxel technology does not lead to an increase in mortality. At the same time, the efficacy results clearly demonstrate that the potential benefits of drug-eluting balloon treatment are maintained over a 5-year period.

Acute soft tissue injury to the temporomandibular joint and posttraumatic assessment after mandibular condyle fractures: a longitudinal prospective MRI study.

OBJECTIVE: Evaluation of acute soft tissue injury of the temporomandibular joint (TMJ) with type I-VI fractures immediately after trauma and investigation of the longitudinal evolution including response to conservative treatment using MRI. METHODS: The joints of 24 patients with 33 condylar fractures (15 unilateral, nine bilateral) were imaged on a 1 Tesla MR system within the first 24 h post-trauma. 12 of these patients with 16 condylar fractures (eight unilateral, four bilateral) were clinically re-evaluated using MRI after 3 months of closed treatment. The position, morphology, and signal intensities of the disc, capsule, retrodiscal tissue, and osseous structures were documented. RESULTS: In the acute phase, disc displacements (DDs) were diagnosed in 8 out of 33 joints with fracture, including posterior DDs in two joints and tears of the inferior retrodiscal lamina in 11 joints. The follow-up MRI in 12 patients revealed new DD in four joints on the fractured side (FS) including a posterior DD and an increased degree of displacement, and new DDs in two joints in the non-fractured side (NFS). CONCLUSION: Preexisting and traumatic DD and soft tissue injuries are frequent findings in patients with condylar fracture. Independent of the degree of trauma, condylar fractures may determine the subsequent development of DD on both FS and NFS. Early MR imaging may help initiate well-directed specific measures for better outcomes in the acutely injured TMJ.

Safety, efficacy, and indications of beta-adrenergic receptor blockade to reduce heart rate prior to coronary CT angiography.

For selected indications, coronary computed tomographic (CT) angiography is an established clinical technology for evaluation in patients suspected of having or known to have coronary artery disease. In coronary CT angiography, image quality is highly dependent on heart rate, with heart rate reduction to less than 60 beats per minute being important for both image quality and radiation dose reduction, especially when single-source CT scanners are used. ß-Blockers are the first-line option for short-term reduction of heart rate prior to coronary CT angiography. In recent years, multiple ß-blocker administration protocols with oral and/or intravenous application have been proposed. This review article provides an overview of the indications, efficacy, and safety of ß-blockade protocols prior to coronary CT angiography with respect to different scanner techniques. Moreover, implications for radiation exposure and left ventricular function analysis are discussed.

T1-weighted MRI for the detection of coronary artery plaque haemorrhage.

OBJECTIVE: Hyperintense areas in atherosclerotic plaques on pre-contrast T1-weighted MRI have been shown to correlate with intraplaque haemorrhage. We evaluated the presence of T1 hyperintensity in coronary artery plaques in coronary artery disease (CAD) patients and correlated results with multi-detector computed tomography (MDCT) findings. METHODS: Fifteen patients with CAD were included. Plaques detected by MDCT were categorised based on their Hounsfield number. T1-weighted inversion recovery (IR) MRI prepared coronary MRI for the detection of plaque and steady-state free-precession coronary MR-angiography for anatomical correlation was performed. After registration of MDCT and MRI, regions of interest were defined on MDCT-visible plaques and in corresponding vessel segments acquired with MRI. MDCT density and MR signal measurement were performed in each plaque. RESULTS: Forty-three plaques were identified with MDCT. With IR-MRI 5/43 (12%) plaques were hyperintense, 2 of which were non-calcified and 3 mixed. Average signal-to-noise and contrast-to-noise ratios of hyperintense plaques were 15.7 and 9.1, compared with 5.6 and 1.2 for hypointense plaques. Hyperintense plaques exhibited a significantly lower CT density than hypointense plaques (63.6 vs. 140.8). There was no correlation of plaque signal intensity with degree of stenosis. CONCLUSION: T1-weighted IR-MRI may be useful for non-invasive detection and characterisation of intraplaque haemorrhage in coronary artery plaques.

Prospective study of access site complications of automated contrast injection with peripheral venous access in MDCT.

OBJECTIVE: The purpose of this article is to prospectively assess the frequency and type of IV injection site complications associated with high-flow power injection of nonionic contrast medium in MDCT. SUBJECTS AND METHODS: Contrast-enhanced (300-370 mg iodine/mL) MDCT examinations with high flow rates (up to 8 mL/s) using automatic CT injectors were performed according to standardized MDCT protocols. The location, type, and size (16-24 gauge) of IV catheters and volumes, iodine concentration, and flow rates of contrast medium were documented. Patients were questioned about associated discomfort, IV catheter sites were checked, and adverse effects were recorded. RESULTS: Prospectively, 4,457 patients were studied. The injection rate ranged from 1-2.9 mL/s (group 1; n = 1,140) to 3-4.9 mL/s (group 2; n = 2,536) to 5-8 mL/s (group 3; n = 781); 1.2% of the patients experienced extravasations (n = 52). Contrast medium iodine concentration, flow rates, and volumes were not related to the frequency of extravasation. The extravasation rate was highest with 22-gauge IV catheters (2.2%; p < 0.05) independently of the anatomic location. For 20-gauge IV catheters, extravasation rates were significantly higher in the dorsum of the hand than in the antecubital fossa (1.8% vs 0.8%; p = 0.018). Extravasation rates were higher in older patients (≥ 50 vs < 50 years, 0.6% vs 1.4%; p = 0.019). Different iodine concentrations did not trigger significant differences in contrast material reactions (p = 0.782). CONCLUSION: Automated IV contrast injection applying high flow rates (i.e., up to 8 mL/s) is performed without increased risk of extravasation. The overall extravasation rate was 1.2% and showed no correlation with iodine concentration, flow rates, or contrast material reactions. Performing high flow rates with low-diameter IV catheters (e.g., 22-gauge catheters) and a location of IV catheter in the hand is associated with a higher extravasation rate.

Update on multidetector coronary CT angiography of coronary stents: in vitro evaluation of 29 different stent types with dual-source CT.

The aim of this study was to test a large sample of the latest coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in dual-source multidetector row CT (DSCT) in vitro and to provide a CT catalogue of currently used coronary artery stents. Twenty-nine different coronary artery stents (19 steel, 6 cobalt-chromium, 2 tantalum, 1 iron, 1 magnesium) were examined in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density -70 HU). Stents were imaged in axial orientation with standard parameters: 32 x 0.6 collimation, pitch 0.24, 400 mAs, 120 kV, rotation time 0.33 s. Image reconstructions were obtained with four different convolution kernels (soft, medium-soft, standard high-resolution, stent-dedicated). To evaluate visualization characteristics of the stent, the lumen diameter, intraluminal density, and noise were measured. The stent-dedicated kernel offered best average lumen visualization (54 +/- 8.3%) and most realistic lumen attenuation (222 +/- 44 HU) at the expense of increased noise (23.9 +/- 1.9 HU) compared with standard CTA protocols (p < 0.001 for all). The magnesium stent showed the least artifacts with a lumen visibility of 90%. The majority of stents (79%) exhibited a lumen visibility of 50-59%. Less than half of the stent lumen was visible in only six stents. Stent lumen visibility largely varies depending on the stent type. Magnesium is by far more favorable a stent material with regard to CT imaging when compared with the more common materials steel, cobalt-chromium, or tantalum. The magnesium stent exhibits a lumen visibility of 90%, whereas the majority of the other stents exhibit a lumen visibility of 50-59%.

Sonographic follow-up of the access site after arterial angiography: Impact on the detected complication rate.

OBJECTIVE: This study prospectively evaluated the impact of sonographic follow-up on the detection rate of access site complications in arterial angiography and determined parameters associated with major complications of the access site after arterial angiography. METHODS: Sonographic follow-up (mean +/- SD, 1.46 +/- 1.11 days after) of the access site (transfemoral, n = 896; and transbrachial, n = 44) was obtained prospectively in 940 arterial angiographies and included evaluations for hematoma, pseudoaneurysm, arteriovenous fistula, arterial dissection, and venous/arterial thrombosis. Clotting parameters, anticoagulation therapy, and several patient and procedure characteristics were recorded. Univariate and multivariate logistic regression analyses were performed. RESULTS: Sonography depicted major access site complications in 39 of 940 angiographies (4.2%). Major access site complications (major local hematoma, n = 13; retroperitoneal hematoma, n = 1; pseudoaneurysm, n = 18; arterial dissection, n = 1; arteriovenous fistula, n = 1; arterial thrombosis, n = 2; and venous thrombosis, n = 3) required conservative (n = 32 [3.4%]) or surgical (n = 7 [0.7%]) treatment. Independent factors significantly associated with major access site complications were age older than 60.33 years and sheath size greater than 5F (P < .05). CONCLUSIONS: Major access site complications were detected in 4.2% of cases and were significantly associated with age and sheath size.

The Randomized Freeway Stent Study: Drug-Eluting Balloons Outperform Standard Balloon Angioplasty for Postdilatation of Nitinol Stents in the SFA and PI Segment.

PURPOSE: The prospective randomized multicenter Freeway study evaluated the possible hemodynamic and clinical benefits of primary stent insertion followed by percutaneous transluminal angioplasty (PTA) with drug-eluting balloons (DEB) over post-stent insertion PTA with standard balloons in the treatment of symptomatic femoropopliteal arteriosclerotic lesions. METHODS: In total, 204 patients in 13 centers in Germany and Austria were enrolled and randomized to primary stenting followed by either FREEWAY™ drug-eluting balloon or standard PTA balloon angioplasty. The primary endpoint was the rate of clinically driven target lesion revascularization (TLR) at 6 months; the secondary endpoints include TLR rate at 12 months and primary patency, shift in Rutherford classification, ankle-brachial index (ABI) and major adverse events (MAE) at 6 and 12 months. Lesion characteristics and vessel patency were analyzed by an independent and blinded corelab. RESULTS: At 6-month and 12-month follow-up, TLR rate was lower in the DEB arm compared to standard PTA but did not reach statistical significance (4.1% vs. 9.0% p = 0.234 and 7.9% vs. 17.7% p = 0.064, respectively). Primary patency was significantly better for patients treated with the DEB at 6 months (90.3% vs. 69.8% p = 0.001) and 12 months (77.4% vs. 61.0% p = 0.027). Improvement in Rutherford classifications was likewise significantly better for patients in the DEB group at 6 (94.9% vs. 84.3% p = 0.027) and 12 months (95.5% vs. 79.9% p = 0.003). The percentage of patients with an improved ABI of 1.0-1.2 was significantly higher in the DEB group compared to the PTA group at 6 months (55.3% vs. 35.3%; p = 0.015) but without significant difference at 12 months (48.2% vs. 32.9%; p = 0.055). At 6 months, rate of major adverse events (MAE) was 1% in both arms, and at 12 months 2.2% for the DEB and 3.8% for the PTA group. CONCLUSION: The Freeway Stent Study shows that the usage of DEB as a restenosis prophylaxis seems to be safe and feasible. The 12-month follow-up results give a clear sign in favor of the DEB group.

Automated threshold-based 3D segmentation versus short-axis planimetry for assessment of global left ventricular function with dual-source MDCT.

OBJECTIVE: The purpose of this study was to evaluate software for threshold-based 3D segmentation of the left ventricle in comparison with traditional 2D short axis-based planimetry (Simpson method) for measurement of left ventricular (LV) volume and global function with state-of-the-art dual-source CT. SUBJECTS AND METHODS: Fifty patients with known or suspected coronary artery disease underwent coronary CT angiography. LV end-diastolic, end-systolic, and stroke volumes and ejection fraction were determined from axial images to which 3D segmentation had been applied and from short-axis reformations from 2D planimetry. Interobserver variability was assessed for both approaches. RESULTS: Threshold-based 3D LV segmentation had excellent correlation with 2D short-axis results (end-diastolic volume, R = 0.99; end-systolic volume, R = 0.99; stroke volume, R = 0.90; ejection fraction, R = 0.97; p < 0.0001). Bland-Altman analyses revealed systematic underestimation of LV end-diastolic volume (-7.4 +/- 8.9 mL) and LV end-systolic volume (-7.0 +/- 4.4 mL) with the 3D segmentation approach and 2.8 +/- 3.3% overestimation of LV ejection fraction. Interobserver variation with 3D segmentation analysis was significantly (p < 0.001) less (e.g., LV ejection fraction, 0.1 +/- 1.7%) than with the 2D technique, and mean analysis time was significantly shorter (172 +/- 20 vs 248 +/- 29 seconds; p < 0.05). CONCLUSION: Automated threshold-based 3D segmentation enables accurate and reproducible dual-source CT assessment of LV volume and function with excellent correlation with results of 2D short-axis analysis. Exclusion of papillary muscles from LV volume results in small systematic differences in quantitative values.

Effective methods to correct contrast agent-induced errors in PET quantification in cardiac PET/CT.

UNLABELLED: In combined PET/CT studies, x-ray attenuation information from the CT scan is generally used for PET attenuation correction. Iodine-containing contrast agents may induce artifacts in the CT-generated attenuation map and lead to an erroneous radioactivity distribution on the corrected PET images. This study evaluated 2 methods of thresholding the CT data to correct these contrast agent-related artifacts. METHODS: PET emission and attenuation data (acquired with and without a contrast agent) were simulated using a cardiac torso software phantom and were obtained from patients. Seven patients with known coronary artery disease underwent 2 electrocardiography-gated CT scans of the heart, the first without a contrast agent and the second with intravenous injection of an iodine-containing contrast agent. A 20-min PET scan (single bed position) covering the same axial range as the CT scans was then obtained 1 h after intravenous injection of (18)F-FDG. For both the simulated data and the patient data, the unenhanced and contrast-enhanced attenuation datasets were used for attenuation correction of the PET data. Additionally, 2 threshold methods (one requiring user interaction) aimed at compensating for the effect of the contrast agent were applied to the contrast-enhanced attenuation data before PET attenuation correction. All PET images were compared by quantitative analysis. RESULTS: Regional radioactivity values in the heart were overestimated when the contrast-enhanced data were used for attenuation correction. For patients, the mean decrease in the left ventricular wall was 23%. Use of either of the proposed compensation methods reduced the quantification error to less than 5%. The required time for postprocessing was minimal for the user-independent method. CONCLUSION: The use of contrast-enhanced CT images for attenuation correction in cardiac PET/CT significantly impairs PET quantification of tracer uptake. The proposed CT correction methods markedly reduced these artifacts; additionally, the user-independent method was time-efficient.

High-resolution magnetic resonance imaging of the temporomandibular joint: image quality at 1.5 and 3.0 Tesla in volunteers.

PURPOSE: To assess the image quality of a high-resolution imaging protocol for the temporomandibular joint (TMJ) at 3.0 T and to compare it with our standard 1.5 T protocol. MATERIALS AND METHODS: Fifteen volunteers without history of TMJ dysfunction underwent bilateral magnetic resonance imaging (MRI) of the TMJ with the jaw in closed and open position. MRI was performed with using a 1.5 T (standard TMJ coil) and 3.0 T (purpose build phased array coil) MR system (Gyroscan Intera 1.5 T and 3.0 T; Philips Medical Systems, Best, the Netherlands). Imaging protocols consisted of a parasagittal PDw-TSE sequence and a coronal PDw-TSE sequence in closed mouth position and a sagittal PDw-TSE sequence in open mouth position. Acquisition parameters were adjusted for 3.0 T and voxel size was reduced from 0.29 x 0.29 x 3.0 mm (1.5 T) to 0.15 x 0.15 x 1.5 mm (3.0 T). Total examination time (15 minutes) was similar for both systems. Two observers assessed in consensus delineation, image quality, and artifacts of anatomic landmarks (disk, bilaminar zone, capsular attachment, cortical bone) and ranked them qualitatively on a 5-point scale from 1 (optimal) to 5 (nondiagnostic). Disk position and motility was noted. For CNR analysis, signal intensity from disk and retrodiscal tissue was measured. RESULTS: Disk position and mobility was identical at both field strengths. All anatomic landmarks were visualized significantly better at 3.0 T. In particular, the capsular attachment was depicted in more detail. Overall image quality was ranked significantly higher at 3.0 T, whereas artifact score was similar. Quantitative evaluation showed significantly higher CNR for 3.0 T (10.23 vs. 8.08, P < 0.0001). CONCLUSION: Depiction of the normal anatomy of the TMJ benefits significantly when investing the higher SNR at 3.0 T into better spatial resolution. We anticipate that this advantage of 3.0 T MRI will also permit a more detailed analysis of capsular and disk pathology.

Comparison of different iodine concentration contrast media in perfusion computed tomography of the brain: is high iodine concentration useful?

OBJECTIVES: To investigate maximum enhancement and visual map quality in cerebral perfusion computed tomography (PCT) with variation of iodine concentration of contrast media (CM). MATERIALS AND METHODS: Two groups of 45 patients each, underwent PCT with either 370 mg iodine/mL (30 mL; 6 mL/s) or 300 mg iodine/mL (40 mL; 8 mL/s) CM, respectively, and similar total iodine dose. Parenchymal and vascular enhancement as well as contrast-to-noise ratio of superior sagittal sinus was measured on PCT source images. PCT maps were rated visually with dichotomized scale for diagnostic quality. RESULTS: Enhancement and contrast-to-noise ratio of the superior sagittal sinus was significantly higher for the 370 mg iodine/mL protocol (P < 0.0002 and P < 0.007), whereas parenchymal enhancement was not significantly different. Diagnostic quality of PCT maps did not differ between both protocols (P < 0.557). CONCLUSIONS: PCT using 370 mg iodine/mL CM can be reliably performed with reduced injection rate and less total volume enabling smaller diameter of intravenous canula compared with 300 mg iodine/mL CM.

Optimal systolic and diastolic reconstruction windows for coronary CT angiography using dual-source CT.

OBJECTIVE: The purpose of this study was to determine the position of the optimal systolic and diastolic reconstruction intervals for coronary CT angiography using dual-source CT. SUBJECTS AND METHODS: In 90 patients, coronary dual-source CT angiography was performed without beta-blocking agents. Data were reconstructed in 5% steps throughout the R-R interval. Two independent readers selected optimal systolic and diastolic reconstruction windows for each major coronary vessel--the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX)--using a 3D viewer and volume-rendering displays. The motion score for each vessel was graded from 1 (no motion artifacts) to 5 (severe motion artifacts over entire vessel). RESULTS: The average heart rate of all patients was 68.7 beats per minute (bpm) (range, 43-119 bpm). The median optimal systolic reconstruction windows were at 35%, 30%, and 35% for the RCA, LAD, and LCX, respectively. The median optimal diastolic reconstruction window was at 75% for all vessels. The mean motion scores (+/- SD) in the systolic reconstructions were 1.9 +/- 0.8 (RCA), 1.7 +/- 0.5 (LAD), and 2.0 +/- 0.6 (LCX). The mean motion scores for the diastolic reconstructions were 1.7 +/- 0.9, 1.5 +/- 0.6, and 1.6 +/- 0.7, respectively. In patients with a heart rate of < 70 bpm, motion scores were significantly lower in diastole versus systole (1.3 +/- 0.4 and 1.9 +/- 0.5, respectively; p < 0.01). In most patients with a heart rate of > 80 bpm, motion scores were lower in systolic than in diastolic reconstructions (2.1 +/- 0.6 and 2.6 +/- 0.8, respectively; p < 0.05). CONCLUSION: Using dual-source CT, the overall optimal reconstruction window is at 75% of the R-R interval in patients with low or intermediate heart rates. In patients with heart rates of > 80 bpm, systolic reconstructions often yield superior image quality compared with diastolic reconstructions.

Intraindividual comparison of 3D coronary MR angiography and coronary CT angiography.

RATIONALE AND OBJECTIVES: To compare the diagnostic value of magnetic resonance (MR) and computed tomography (CT) for the detection of coronary artery disease (CAD) with special regard to calcifications. MATERIALS AND METHODS: Twenty-seven patients with known CAD were examined with a targeted, navigator-gated, free-breathing, steady-state free precession MR angiography sequence (repetition time = 5.6 milliseconds, echo time = 2.8 milliseconds, flip angle 110 degrees ) and 16-slice coronary CT angiography. Segment-based sensitivity, specificity, and accuracy for the detection of stenoses larger than 50% were determined as defined by the gold standard catheter coronary angiography along with the subjective image quality (Grade 1-4). The degree of calcifications in each segment was quantified using a standard calcium scoring tool. RESULTS: Of 115 possible segments, 7% had to be excluded in MR imaging because of poor image quality. In CT, 3% were nondiagnostic because of image quality and 15% were not evaluable because of calcifications. Values for the detection of relevant coronary artery stenoses in the evaluated segments were: sensitivity: MR imaging 85% versus CT 96%; specificity: 88% versus 96%; accuracy: 87% versus. 96%. Average subjective image quality was 1.8 for MR imaging and 1.6 for CT. Of the 15% of segments that had to be excluded from CT evaluation because of calcifications, MR imaging provided the correct diagnosis segments in 67%. CONCLUSIONS: CT provided a better image quality with superior accuracy for the detection of CAD. Despite its overall inferiority, MR imaging proved to be helpful method in interpreting coronary stenosis in severely calcified segments.

64- Versus 16-slice CT angiography for coronary artery stent assessment: in vitro experience.

OBJECTIVES: We sought to assess the visualization of different coronary artery stents and the delineation of in-stent stenoses using 64- and 16-slice multidector computed tomography (MDCT). MATERIALS AND METHODS: A total of 15 different coronary stents with a simulated in-stent stenosis were placed in a vascular phantom and scanned with a 16-slice and a 64-slice MDCT at orientations of 0 degree, 45 degrees, and 90 degrees relative to the scanner's z-axis. Visible lumen diameter and attenuation in the stented and the unstented segment of the phantom were measured. Three readers assessed stenosis delineation and visualization of the residual lumen using a 5-point scale. RESULTS: Artificial lumen narrowing (ALN) was significantly reduced with 64-slice CT compared with 16-slice CT. At an angle of 0 degree, 45 degrees, and 90 degrees relative to the scanner's z-axis, the ALN for 16-slice CT was 42.2%, 39.8%, and 44.0% using a slice-thickness of 1.0 mm and 40.9%, 40.4%, and 41.6% using a slice thickness of 0.75 mm, respectively. With 64-slice CT, the ALN was 39.1%, 37.3%, and 36.0% at the respective angles. The differences between attenuation values in the stented and unstented segment of the tube were significantly lower for 64-slice CT. Mean visibility scores were significantly higher for 64-slice CT. CONCLUSION: Use of the 64-slice CT results in superior visualization of the stent lumen and in-stent stenosis compared with 16-slice CT, especially when the stent is orientated parallel to the x-ray beam.

Electrocardiogram-independent image reconstruction in cardiac multidetector computed tomography using retrospective motion synchronization.

OBJECTIVE: We sought to evaluate an electrocardiogram (ECG)-independent image reconstruction technique for coronary computed tomography (CT)-angiography based on cardiac motion. MATERIALS AND METHODS: The raw data from 20 patients was reconstructed with both an ECG-gated algorithm and a motion-dependent algorithm that calculates the cardiac motion-function directly from the CT raw data using a center of mass technique. Images were reconstructed in 5% steps over the R-R interval and the cardiac motion-cycle. For both approaches multiplanar reformations were created and the set of images with the least motion artifacts was used for the evaluation. Motion artifacts affecting the ascending aorta, the left main coronary artery and the entire course of the LAD, LCX and RCA were scored using a 5-point scale. RESULTS: The mean optimal reconstruction window was at 60% of the R-R interval and 30% of the cardiac motion cycle. A total of 73 of 100 vascular regions showed no motion artifacts in ECG-gated images, with the motion-synchronized algorithm only 41 regions were free of motion artifacts. The mean motion-score was 1.4 (+/-0.6) and 2.4 (+/-1.2) respectively (P < 0.05). CONCLUSION: In the currently implemented form the motion-gated algorithm is inferior to ECG-gated image reconstruction but can be used in patients with an incomplete or corrupt ECG-signal.

MDCT determination of volume and function of the left ventricle: are short-axis image reformations necessary?

OBJECTIVE: Determination of left ventricular (LV) volumes and global function parameters from MDCT data sets is usually based on short-axis reformations from primarily reconstructed axial images, which prolong postprocessing time. The aim of this study was to evaluate the feasibility of LV volumetry and global LV function assessment from axial images in comparison with short-axis image reformations. SUBJECTS AND METHODS: This study consisted of 20 patients with either coronary artery disease or dilated cardiomyopathy. We evaluated MDCT results using cine MRI as the reference technique. RESULTS: LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were significantly overestimated by the axial MDCT approach in comparison with volume measurements from short-axis CT image reformations. The mean LV ejection fraction (LVEF) was not significantly different (41.2% vs 42.7%). Short-axis and axial MDCT determination of LVEF revealed a systematic underestimation by a mean +/- SD of -2.1% +/- 3.6% versus -3.6% +/- 8.2%, respectively, when compared with LVEF values based on cine MRI. The interobserver variability for volume and function measurements from axial images (LVEDV = 8.5%, LVESV = 10.8%, LVEF = 9.6%) was slightly higher than those measurements from short-axis reformations (LVEDV = 7.2%, LVESV = 9.5%, LVEF = 8.7%). The mean total evaluation time was significantly shorter using axial images (14.1 +/- 3.9 min) compared with short-axis reformations (16.9 +/- 5.2 min) (p < 0.05). CONCLUSION: Determination of LV volumes and assessment of global LV function from axial MDCT image reformations is feasible and time efficient. This approach might be a clinically useful alternative to established short-axis-based measurements in patients with normal or near-normal LV function. A progressive underestimation of LVEF with increasing LV volumes may limit the clinical applicability of the axial approach in patients with dilated cardiomyopathy.

Improved coronary artery stent visualization and in-stent stenosis detection using 16-slice computed-tomography and dedicated image reconstruction technique.

OBJECTIVE: The aim of this study was to compare the visualization of different coronary artery stents and the detectability of in-stent stenoses during 4-slice and 16-slice computed tomography (CT) angiography in a vessel phantom. MATERIAL AND METHODS: Ten coronary stents were introduced in a coronary artery vessel phantom (plastic tubes with an inner diameter of 3 mm, filled with iodinated contrast material diluted to 220 Hounsfiled Units [HU], surrounded by oil [60 HU]). CT scans were obtained perpendicular to the stent axes on a 4-slice scanner (detector collimation 4x1 mm; table feed 1.5 mm/rotation, mAs 300, kV 120, medium-smooth kernel) and a 16-slice scanner (detector collimation 12x0.75 mm; table feed 2.8 mm/rotation, mAs 370, kV 120, reconstruction with a standard and an optimized sharp kernel). Longitudinal multiplanar reformations were evaluated regarding visible lumen diameters and intraluminal attenuation values. Additionally, the stents were scanned with the same parameters after implantation of 60% stenoses (HU 30). RESULTS: Using the same medium-smooth kernel reconstruction with 4-slice and 16-slice CT, there was a slight increase in the average visible lumen area (26% versus 31%) and less increase of average intraluminal attenuation values (380 HU versus 349 HU). Significant improvement of lumen visualization (54%, P<0.01) and attenuation values (250, P<0.01) was observed for the 16-slice scans using the sharp kernel reconstruction. In-stent stenoses could be more reliably identified (or ruled out) by 16-slice CT and sharp reconstruction kernel when compared with the other 2 methods. CONCLUSION: 16-slice CT using a dedicated sharp kernel for image reconstruction facilitates improved visualization of coronary artery stent lumen and detection of in-stent stenoses.