MRI versus CT for the detection of coronary artery disease: Current state and future promises

CT and MR are two noninvasive imaging techniques that are capable of detecting different aspects of coronary artery disease (CAD). Both techniques can directly and noninvasively visualize the coronary artery tree, allowing detection of atherosclerotic plaques, coronary stenosis, or occlusion. In addition to direct anatomic visualization, MR also allows assessment of stress-induced ischemia. Both dobutamine stress and dipyridamole or adenosine perfusion MR can be used for this purpose with high sensitivity and specificity. Both MR and multidetector CT can also reveal the functional consequences of CAD, that is, reduced regional and global cardiac function, as well as the presence of myocardial infarction. Finally, there is promise that in the future, both techniques may predict individual risk of unstable CAD by identifying vulnerable plaques that are prone to rupture.     

Transgastric pancreatography and EUS-guided drainage of the pancreatic duct

Background/Purpose

Endoscopic transpapillary drainage of the retained pancreatic duct in symptomatic patients with chronic pancreatitis is considered an established treatment option. The aim of this study was to investigate, as an alternative, endoscopic ultrasound (EUS)-guided transgastric pancreatography and drainage of the pancreatic duct, in terms of their feasibility and outcome.

Methods

All consecutive symptomatic patients with failure of the traditional approach to catheterize and drain the pancreatic duct, over a 3-year time period, were enrolled in this prospective, observational single-center study (case series). Feasibility was characterized by success rate, outcome by complication rate (frequency of bleeding or perforation), mortality, and follow-up.

Results

Twelve patients underwent 14 interventions (sex ratio, M/F, 10?:?4; age range, 43–77 years) from November 2002 to October 2005. The main indication was retention of the pancreatic duct associated with pain, in particular: (i) papilla not reachable because of prior gastrointestinal surgery (n = 5); and (ii) not possible to introduce the catheter through the papilla in chronic pancreatitis or “pancreas divisum” (n = 7). Pancreatography was successful in all patients (normal finding with no therapeutic consequence, n = 1 [after pancreaticojejunostomy]), whereas drainage of the pancreatic duct was achieved in 9 patients (69%; attempts, n = 13). The transgastric route was used in 5 patients and the transpapillary route (rendezvous technique with endoscopic retrograde cholangiopancreatography [ERCP]) in 4. There was a complication rate of 42.9%, comprising postinterventional pain (n = 4; 28.6%); bleeding (n = 1); and perforation because of retriever problems (n = 1). The postinterventional pancreatitis rate was 0% and mortality was 0%. The follow-up investigation (range, 4 weeks ? 3 years) revealed that 4 patients (28.6%) subsequently underwent surgical intervention, because of duodenal stenosis (n = 1; 7.1%), suspicious tumor growth (n = 1; 7.1%), and insufficient drainage of the pancreatic duct (n = 2; 14.3%). In 2 subjects (14.3%), endoscopic reinterventions became necessary, which were subsequently successful. There were the following technical problems: 1) Too dense stenosis (n = 3); 2) inadequate equipment (insufficient infeed of the endoscopic tool because of its bending), in each case.

Conclusions

Transgastric pancreatography and EUS-guided drainage of the pancreatic duct are reasonable and feasible alternative options for diagnostic and therapeutic management for selected indications (chronic pancreatitis; anomaly of the congenital pancreatic or postoperative gastrointestinal anatomy), with an acceptable periinterventional risk, which broaden the therapeutic spectrum and may avoid surgery but need further evaluation and follow-up investigation.

     

Distribution of intracellular and secreted surfactant during postnatal rat lung development

Pulmonary surfactant prevents alveolar collapse via reduction of surface tension. In contrast to human neonates, rats are born with saccular lungs. Therefore, rat lungs serve as a model for investigation of the surfactant system during postnatal alveolar formation. We hypothesized that this process is associated with characteristic structural and biochemical surfactant alterations. We aimed to discriminate changes related to alveolarization from those being either invariable or follow continuous patterns of postnatal changes. Secreted active (mainly tubular myelin (tm)) and inactive (unilamellar vesicles (ulv)) surfactant subtypes as well as intracellular surfactant (lamellar bodies (lb)) in type II pneumocytes (PNII) were quantified before (day (d) 1), during (d 7), at the end of alveolarization (d 14), and after completion of lung maturation (d 42) using electron microscopic methods supplemented by biochemical analyses (phospholipid quantification, immunoblotting for SP-A). Immunoelectron microscopy determined the localization of surfactant protein A (SP-A). (1) At d 1 secreted surfactant was increased relative to d 7-42 and then decreased significantly. (2) Air spaces of neonatal lungs comprised lower fractions of tm and increased ulv, which correlated with low SP-A concentrations in lung lavage fluid (LLF) and increased respiratory rates, respectively. (3) Alveolarization (d 7-14) was associated with decreasing PNII size although volume and sizes of Lb continuously increased. (4) The volume fractions of Lb correlated well with the pool sizes of phospholipids in lavaged lungs. Our study emphasizes differential patterns of developmental changes of the surfactant system relative to postnatal alveolarization.     

Retrospective motion gating in small animal CT of mice and rats

OBJECTIVES: Implementation and evaluation of retrospective respiratory and cardiac gating of mice and rats using a flat-panel volume-CT prototype (fpVCT). MATERIALS AND METHODS: Respiratory and cardiac gating was implemented by equipping a fpVCT with a small animal monitoring unit. ECG and breathing excursions were recorded and 2 binary gating signals derived. Mice and rats were scanned continuously over 80 seconds after administration of blood-pool contrast media. Projections were chosen to reconstruct volumes that fall within defined phases of the cardiac/respiratory cycle. RESULTS: Multireader analysis indicated that in gated still images motion artifacts were strongly reduced and diaphragm, tracheobronchial tract, heart, and vessels sharply delineated. From 4D series, functional data such as respiratory tidal volume and cardiac ejection fraction were calculated and matched well with values known from literature. DISCUSSION: Implementation of retrospective gating in fpVCT improves image quality and opens new perspectives for functional cardiac and lung imaging in small animals.     

A new self-expanding nitinol stent (Enterprise) for the treatment of wide-necked intracranial aneurysms: initial clinical and angiographic results in 31 aneurysms

Introduction We report the results of a prospective clinical study using a new self-expanding nitinol stent (Enterprise) designed for the treatment of wide-necked intracranial aneurysms. Methods We treated 31 saccular, wide-necked intracranial aneurysms in 30 patients. Ten aneurysms had recanalized after prior endovascular treatment without a stent, and 21 aneurysms had not been treated before. Results Stent deployment was successful in all procedures. Additional coil embolization was performed in all aneurysms. Initial complete angiographic occlusion was achieved in 6 aneurysms, a neck remnant was left in 18 aneurysms and there were 7 residual aneurysms. Angiographic follow-up examinations of 30 lesions after 6 months demonstrated 15 complete occlusions, 8 neck remnants and 7 residual aneurysms. One patient refused the 6-month angiographic follow-up. Spontaneous occlusion of the aneurysm had occurred in 14 patients, and 6 aneurysms showed recanalization. Four of these residual aneurysms were retreated. At the 6-month follow-up, 29 parent arteries were unaffected, whereas two parent vessels demonstrated minor asymptomatic narrowing at the stent site. Two patients experienced one or more possible or probable device-related serious adverse events during the 6-month follow-up period. There was no procedural morbidity or mortality at 6 months after the procedure. Conclusion The reported results demonstrated the safety and feasibility of the Cordis Neurovascular Enterprise stent in the treatment of wide-necked intracranial aneurysms. Initial clinical and angiographic results are favorable. Werner Weber and Martin Bendszus contributed equally to this work.     

MR myocardial perfusion imaging with k-space and time broad-use linear acquisition speed-up technique: feasibility study

The purpose of this study was to prospectively evaluate the diagnostic accuracy of a cardiovascular magnetic resonance (MR) k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) accelerated perfusion sequence for depicting clinically relevant coronary artery disease (CAD), with use of coronary angiography as the reference standard. The local ethics committee approved this study, and informed consent was obtained from 40 patients (28 men, 12 women; mean age, 61 years +/- 8 [standard deviation]) scheduled for coronary catheterization. A balanced steady-state free precession pulse sequence (2.6 x 2.6 x 10 mm) with a net k-t acceleration factor of 3.8 (repetition time msec/echo time msec, 3.2/1.6; flip angle, 50 degrees ) was applied. Visual analysis of perfusion images and quantitative analysis of signal-time curves obtained in the myocardium were performed by using segmental myocardial upslope, peak enhancement, and their respective ratios. Visual analysis revealed sensitivity, specificity, and diagnostic accuracy of 86%, 78%, and 83%, respectively, in the detection of coronary stenoses with at least 50% luminal narrowing. Significant (P < .05) changes between ischemic and remote segments could be shown for all perfusion indexes applied. Use of myocardial perfusion imaging with k-t BLAST for accelerated data acquisition is feasible in the identification of patients with substantial CAD (coronary stenosis >or= 50%). Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/245/3/863/DC1.