Coronary MR angiography using citrate-coated very small superparamagnetic iron oxide particles as blood-pool contrast agent: initial experience in humans.

PURPOSE: To evaluate very small superparamagnetic iron oxide particles (VSOP-C184) as blood-pool contrast agent for coronary MR angiography (CMRA) in humans. MATERIALS AND METHODS: Six healthy volunteers and 14 patients with suspected coronary artery disease underwent CMRA after administration of VSOP-C184 at the following doses: 20 µmol Fe/kg (4 patients), 40 µmol Fe/kg (5 patients), 45 µmol Fe/kg (6 healthy volunteers), and 60 µmol Fe/kg (5 patients). In healthy volunteers, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and vessel edge definition (VED) of contrast-enhanced CMRA were compared with non-contrast-enhanced CMRA. In patients, a per-segment intention-to-diagnose evaluation of contrast-enhanced CMRA for detection of significant coronary stenosis (≥50%) was performed. RESULTS: Three healthy volunteers (45 µmol Fe/kg VSOP-C184) and two patients (60 µmol Fe/kg VSOP-C184) had adverse events of mild or moderate intensity. VSOP-C184 significantly increased CNR (15.1 ± 4.6 versus 6.9 ± 1.9; P = 0.010), SNR (21.7 ± 5.3 versus 15.4 ± 1.6; P = 0.048), and VED (2.3 ± 0.6 versus 1.2 ± 0.2; P < 0.001) compared with non-contrast-enhanced CMRA. In patients, contrast-enhanced CMRA yielded sensitivity, specificity, and diagnostic accuracy for detection of significant coronary stenosis of 86.7%, 71.0%, 73.1%, respectively. CONCLUSION: CMRA using VSOP-C184 was feasible and yielded moderate diagnostic accuracy for detection of significant coronary stenosis within this proof-of-concept setting.

Efficient whole-body MRI interpretation: evaluation of a dedicated software prototype.

The study investigates the performance of a dedicated whole-body magnetic resonance imaging (MRI) interpretation software with regard to diagnostic efficiency using quantitative and qualitative parameters. Forty-eight oncologic patients underwent whole-body computed tomography (WB-CT) and whole-body magnetic resonance imaging (WB-MRI). In a quantitative analysis, the times needed for interpretation of the CT and MRI datasets were measured. The MRI studies were read using a standard workstation and the whole-body MRI interpretation software, respectively. In the qualitative analysis, the numbers of metastases were separately recorded for 13 organ systems, again interpreting the MRI images on the standard workstation and with the dedicated software. Moreover, user friendliness and system usability were evaluated using a standardized questionnaire. Use of the whole-body MRI interpretation software significantly reduced the MRI interpretation time compared with the standard workstation. There was no significant difference between interpretation time of WB-CT and interpretation time of WB-MRI using the dedicated software. Comparison with WB-CT as the reference method demonstrated no significant difference between the whole-body MRI interpretation software prototype and the standard interpretation software in the number of metastases detected. In conclusion, the use of the dedicated whole-body reading software improves the interpretation process of WB-MRI studies with respect to time efficiency and system usability.

Multisegment and halfscan reconstruction of 16-slice computed tomography for detection of coronary artery stenoses.

RATIONALE AND OBJECTIVES: To compare the diagnostic accuracy and image quality of 2 reconstruction algorithms (multisegment and halfscan) for computed tomography (CT) coronary angiography in patients without beta-blocker medication. MATERIALS AND METHODS: Thirty-four patients with 42 significant coronary stenoses in 136 main coronary branches were examined using a 16-slice CT scanner (Aquilion, Toshiba, Otawara, Japan). Twenty-seven patients (79%) had heart rates above 65 beats/min. RESULTS: Without exclusion of branches the sensitivity, specificity, accuracy, and rate of nonassessable segments with multisegment versus halfscan reconstruction were 88 versus 74%, 91 versus 71%, 90 versus 72%, and 2 versus 21% (P < 0.01), respectively. Multisegment reconstruction improved the average vessel length free of motion artifacts by 56% compared with halfscan reconstruction (P < 0.01). Image quality in terms of vessel continuity and visibility of side branches (P < 0.005) was significantly better using multisegment reconstruction. CONCLUSIONS: Multisegment reconstruction has superior diagnostic accuracy and image quality compared with halfscan reconstruction in patients with normal heart rates.

Late diagnosis of pedicle screw malplacement with perforation of the thoracic aorta after posterior stabilization in a patient with multiple myeloma: case report.

STUDY DESIGN: A case report. OBJECTIVE: To demonstrate delayed diagnosis of screw malpositioning with perforation of the thoracic aorta after posterior stabilization of a Th7-vertebral collapse due to multiple myeloma. Relevant diagnostic and therapeutic strategies are outlined in the context of a rather unfortunate series of interventional events. SUMMARY OF BACKGROUND DATA: Pedicle screw instrumentation has become a well-established standard in the surgical treatment of various disorders of the spinal column. Particularly at the upper-thoracic level, the close anatomic relationship of the spine to the aorta places it and other major structures at high risk. Although iatrogenic vascular injuries are rare, a few cases have been described. METHODS: A 64-year-old female patient remarked progressive back pain after 2 years of uneventful recovery from a multilevel posterior stabilization by pedicle screw and rod instrumentation because of an osteolytic collapse of the Th7 vertebra. The subsequent computed tomographic scan demonstrated kyphotic deformity of the thoracic spine with transspinal and periaortic screw malplacement. RESULTS: The revision strategy was an interdisciplinary single session two-phase operation. The primary phase included a left-sided thoracotomy, mobilization of the thoracic aorta, and posterior implant removal under vascular monitoring in right lateral position. The initially planned corporectomy of Th7 and subsequent vertebral body replacement by cage implantation via the anterior approach was dismissed because of critical tissue adhesions of the thoracic aorta to the anterior vertebral column. Finally, the thoracotomy was closed, the patient transferred into prone position and stabilized by a multilevel posterior reinstrumentation under fluoroscopy guidance. CONCLUSION: Although the clinical course in malpositioned pedicle screw instrumentation may stay unremarkable, this case illustrates that in a proven injury to the thoracic aorta revision is mandatory to prevent further vascular damage. The appropriate strategy demands exact and provident planning using a preferably interdisciplinary approach.

Computer-aided detection in computed tomography colonography with full fecal tagging: comparison of standalone performance of 3 automated polyp detection systems.

PURPOSE: We sought to compare the performance of 3 computer-aided detection (CAD) polyp algorithms in computed tomography colonography (CTC) with fecal tagging. METHODS: CTC data sets of 33 patients were retrospectively analysed by 3 different CAD systems: system 1, MedicSight; system 2, Colon CAD; and system 3, Polyp Enhanced View. The polyp database comprised 53 lesions, including 6 cases of colorectal cancer, and was established by consensus reading and comparison with colonoscopy. Lesions ranged from 6-40 mm, with 25 lesions larger than 10 mm in size. Detection and false-positive (FP) rates were calculated. RESULTS: CAD systems 1 and 2 could be set to have varying sensitivities with higher FP rates for higher sensitivity levels. Sensitivities for system 1 ranged from 73%-94% for all lesions (78%-100% for lesions > or =10 mm) and, for system 2, from 64%-94% (78%-100% for lesions > or =10 mm). System 3 reached an overall sensitivity of 76% (100% for lesions > or =10 mm). The mean FP rate per patient ranged from 8-32 for system 1, from 1-8 for system 2, and was 5 for system 3. At the highest sensitivity level for all polyps (94%), system 2 showed a statistically significant lower FP rate compared with system 1 (P = .001). When analysing lesions > or =10 mm, system 3 had significantly fewer FPs than systems 1 and 2 (P < .012). CONCLUSIONS: Standalone CTC-CAD analysis in the selected patient collective showed the 3 systems tested to have a variable but overall promising performance with respect to sensitivity and the FP rate.

Evaluation of left and right ventricular diastolic function by electron-beam computed tomography in patients with passive epicardial constraint.

OBJECTIVE: Previous investigations have shown the usefulness of electron-beam computed tomography (EBCT) to describe ventricular diastolic function and to detect constrictive filling pattern. We used EBCT to analyze diastolic function in patients who underwent passive epicardial constraint because data describing ventricular filling in these patients are still incomplete. METHODS: Ten patients with dilated cardiomyopathy (group 1) underwent EBCT examination before and again 6 months after surgery. Ten patients with normal diastolic function (group 2) and 5 male patients with constrictive pericarditis (group 3) served for comparison. Volume-time curves throughout the entire diastole were generated, and the rapidity of diastolic filling was assessed by calculating the percent filling fraction at consecutive EBCT frames throughout the diastole. Pericardial thickness was measured in a standardized fashion at different locations around both ventricles. RESULTS: Early left ventricular filling pattern in group 1 did not change postoperatively (filling fraction at third diastolic frame was 50.0 +/- 15.4% and 53.8 +/- 14.4% before and after surgery, respectively) and was not significantly different from group 2 (48.7 +/- 8.5%). In contrast, in group 3, early left ventricular filling was significantly accelerated (71.4 +/- 9.3%) when compared with groups 1 and 2. A similar pattern was observed for the right ventricle. Pericardial thickness between groups 1 (1.22 +/- 4.22 and 1.43 +/- 0.39 mm before and after surgery, respectively) and 2 (1.38 +/- 0.43 mm) did not differ significantly. In contrast, pericardium in group 3 was significantly thickened (4.93 +/- 1.11 mm) when compared with both groups 1 and 2. CONCLUSIONS: The EBCT identified an abnormal accelerated diastolic filling and thickened pericardium in patients with constrictive pericarditis. Conversely, a normal diastolic filling pattern and pericardial thickness seem to be preserved in patients after passive epicardial constraint, when compared with baseline values and with normal subjects.

Electrocardiographic-gated multislice computed tomography for visualization of cardiac morphology in congenitally corrected transposition of the great arteries.

A case of congenitally corrected transposition of the great arteries in a 64-old-woman is presented. Diagnosis was missed by invasive angiocardiography. Electrocardiographic-gated multislice computed tomography not only demonstrated switching of the aortic root and pulmonary trunk but clearly identified fine morphologic details of the cardiac chambers, including the atypical coronary artery pattern.