Assessment of global right ventricular function on 64-MDCT compared with MRI.

OBJECTIVE: The aim of this study was to compare ECG-gated 64-MDCT with MRI for the assessment of global right ventricular (RV) function from coronary CT angiography data. SUBJECTS AND METHODS: Thirty-eight patients (25 men, 13 women; mean age +/- SD, 55.0 +/- 8.8 years) with suspected coronary artery disease underwent contrast-enhanced 64-MDCT (64 x 0.6 mm, 120 kV, 770 mAs(eff)) and 1.5-T MRI (balanced fast-field echo; TR/TE, 3.3/1.6; flip angle, 60 degrees ; 50 phases). Double oblique short-axis MDCT and MR images were used for further analysis. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were computed from manually drawn endocardial contours of the right ventricle. For statistical analysis, repeated-measures analysis of variance and Pearson's correlation coefficients were calculated. Bland-Altman plots were computed. RESULTS: In general, RV volumes calculated from 64-MDCT agreed well with those calculated from MRI. The mean EF (+/- SD) calculated from MDCT and MRI was 51.0% +/- 7.8% and 51.4% +/- 7.3%, respectively. An excellent correlation was observed for EDV (r = 0.99), ESV (r = 0.98), SV (r = 0.98), and EF (r = 0.97). Bland-Altman plots showed no systematic variation between MDCT and MRI data. No statistically significant differences (p < or = 0.05) between the techniques were found. CONCLUSION: Although contrast injection is optimized for visualization of the coronary arteries, retrospectively ECG-gated 64-MDCT permits reliable assessment of global RV function.

Absolute concentrations of high-energy phosphate metabolites in normal, hypertrophied, and failing human myocardium measured noninvasively with (31)P-SLOOP magnetic resonance spectroscopy.

OBJECTIVE: The purpose of the present study was to measure absolute concentrations of phosphocreatine (PCr) and adenosine triphosphate (ATP) in normal, hypertrophied, and failing human heart. BACKGROUND: Conflicting evidence exists on the extent of changes of high-energy phosphate metabolites in hypertrophied and failing human heart. Previous reports using phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) have quantified metabolites in relative terms only. However, this analysis cannot detect simultaneous reductions. METHODS: Four groups of subjects (n = 10 each), were studied: volunteers and patients with hypertensive heart disease (HHD), aortic stenosis, and dilated cardiomyopathy (DCM). Left ventricular (LV) function and mass were measured by cine magnetic resonance imaging. Absolute and relative concentrations of PCr and ATP were determined by (31)P-MRS with spatial localization with optimum point spread function. RESULTS: Left ventricular ejection fraction remained normal in HHD and aortic stenosis, but was severely reduced to 18% in DCM; LV mass was increased by 55%, 79%, and 68% respectively. In volunteers, PCr and ATP concentrations were 8.82 +/- 1.30 mmol/kg wet weight and 5.69 +/- 1.02 mmol/kg wet weight, and the PCr/ATP ratio was 1.59 +/- 0.33. High-energy phosphate levels were unaltered in HHD. In aortic stenosis, PCr was decreased by 28%, whereas ATP remained constant. In DCM, PCr was reduced by 51%, ATP by 35%, and reduction of the PCr/ATP ratio by 25% was of borderline significance (p = 0.06). Significant correlations were observed among energetic and functional variables, with the closest relations for PCr. CONCLUSIONS: In human heart failure due to DCM, both PCr and ATP are significantly reduced. Ratios of PCr to ATP underestimate changes of high-energy phosphate levels.

Flat-panel detector computed tomography for the assessment of coronary artery stents: phantom study in comparison with 16-slice spiral computed tomography.

PURPOSE: The evaluation of coronary artery stents is a major limitation of cardiac multislice spiral computed tomography (MSCT). The development of flat-panel detector computed tomography (FPCT) with truly isotropic spatial resolution may overcome this limitation. Thus, we evaluated the use of FPCT in comparison to MSCT for the assessment of coronary artery stents. MATERIAL AND METHODS: Eight different coronary artery stents with a diameter of 3 mm each were placed in a static chest phantom. The phantom was positioned in the CT gantry at angles of 0 degrees , 45 degrees , and 90 degrees toward the z-axis and examined with the prototype of a FPCT (Siemens, Forchheim, Germany) and a commercially available 16-detector row MSCT (Sensation 16, Siemens). Slice thickness was 0.25 mm with FPCT whereas for MSCT, an effective slice thickness of 1 mm with a reconstruction increment of 0.5 mm was used. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using a repeated-measures analysis of variance. RESULTS: When compared with MSCT, artificial lumen reduction was significantly less using FPCT. On average the visible stent lumen was reduced by 16.1% with FPCT, whereas the mean of the lumen reduction was 47.2% with 16-detector row MSCT. Visible lumen diameter as well as image noise significantly increased using FPCT (P < 0.001). With FPCT delineation of the different stent struts became possible. CONCLUSION: FPCT proved to be superior when compared with 16-detector row MSCT for the in vitro assessment of coronary artery stents. Improved spatial resolution allows for a detailed assessment of the coronary artery stent lumen.

Diagnostic value of 64-slice multi-detector row cardiac CTA in symptomatic patients.

Cardiac multi-detector-row computed tomography (MDCT) angiography has shown high levels of sensitivity and especially negative predictive value regarding the diagnosis of coronary artery disease (CAD). This study was designed to determine the value of a 64-slice-MDCT scanner in comparison to invasive coronary angiography for the detection of CAD in a population of symptomatic patients. Fifty-one patients with suspected CAD underwent conventional coronary angiography and ECG-gated cardiac 64-slice-MDCT angiography with a rotation time of 330 ms, a collimation of 64x0.6 mm and a slice thickness of 0.75 mm. Blinded patient- and segment-based analysis was performed for the detection of stenoses >or=70% of the vessel lumen. 95% of all coronary segments were assessable by MDCT angiography. Patient-based (segment-based) analysis revealed a sensitivity of 97.8% (86.7%), specificity of 50% (95.2%), positive predictive value of 93.6% (75.2%) and negative predictive value of 75% (97.7%). Inter-rater agreement revealed a kappa-value of 0.558 (0.722). In this symptomatic patient group a 64-slice-MDCT scanner shows good agreement on a segment-based analysis but only moderate agreement on a patient-based analysis. The diagnostic accuracy of 64-slice-MDCT coronary angiography is negatively influenced by the high pre-test probability of this symptomatic patient collective.

Vessel density ratio: A novel approach to identify "culprit" coronary lesion by spiral computed tomography.

BACKGROUND AND OBJECTIVE: We hypothesized that a "culprit" lesion in acute coronary syndrome (ACS) should have low overall vessel lumen and plaque density on multidetector computed tomography-assisted coronary angiography (MDCTA) because of lower calcification and the presence of occlusive thrombus. However, thrombi and calcification both can themselves blur the demarcation between vessel wall and lumen. If we calculated a "vessel density ratio" (VDR) obtained by measuring the mean density of contrast-enhancement within a region of interest (ROI), which includes the vessel wall, lumen, plaque, and thrombus, and comparing that with the aortic root mean density acting as a reference point, this ratio may be more convenient, standardized, and reproducible to test the feasibility of VDR in identifying "culprit" lesions in ACS. METHODS: Sixty-four patients-21 exertional angina; 17 unstable angina/non-ST elevation myocardial infarction (NSTEMI); 26 ST elevation myocardial infarction (STEMI)-provided 188 diseased segments on conventional angiography. All underwent MDCTA within a week of angiography. ROI was mapped out from maximum intensity projections of diseased segments in planar view. RESULTS: One hundred seventy-four segments were evaluated. Patients who presented with ACS (STEMI and unstable angina/non-ST elevation myocardial infarction) had lower mean VDR compared to patients with exertional angina (0.58 vs. 0.66 vs. 0.81; P < 0.001). Culprit lesions in ACS patients also had the lowest mean VDR when compared to nonculprit lesions and lesions in patients without ACS (0.51 vs. 0.68 vs. 0.81; P < 0.001). CONCLUSIONS: VDR is a new, convenient, and standardized approach in identifying "culprit" lesions by MDCTA.

Age and gender dependence of human cardiac phosphorus metabolites determined by SLOOP 31P MR spectroscopy.

The aim of this study was to apply (31)P magnetic resonance spectroscopy (MRS) using spatial localization with optimal point spread function (SLOOP) to investigate possible age and gender dependencies of the energy metabolite concentrations in the human heart. Thirty healthy volunteers (18 males and 12 females, 21-67 years old, mean = 40.7 years) were examined with the use of (31)P-MRS on a 1.5 T scanner. Intra- and interobserver variability measures (determined in eight of the volunteers) were both 3.8% for phosphocreatine (PCr), and 4.7% and 8.3%, respectively, for adenosine triphosphate (ATP). High-energy phosphate (HEP) concentrations in mmol/kg wet weight were 9.7 +/- 2.4 (age < 40 years, N = 16) and 7.7 +/- 2.5 (age >or= 40 years, N = 14) for PCr, and 5.1 +/- 1.0 (age < 40 years) and 4.1 +/- 0.8 (age >or= 40 years) for ATP, respectively. Separated by gender, PCr concentrations of 9.2 +/- 2.4 (men, N = 18) and 8.0 +/- 2.8 (women, N = 12) and ATP concentrations of 4.9 +/- 1.0 (men) and 4.2 +/- 0.9 (women) were measured. A significant decrease of PCr and ATP was found for volunteers older than 40 years (P < 0.05), but the differences in metabolic concentrations between both sexes were not significant. In conclusion, age has a minor but still significant impact on cardiac energy metabolism, and no significant gender differences were detected.

Computer-assisted detection of pulmonary nodules: evaluation of diagnostic performance using an expert knowledge-based detection system with variable reconstruction slice thickness settings.

The purpose of this study was to evaluate the performance of a computer-assisted diagnostic (CAD) tool using various reconstruction slice thicknesses (RST). Image data of 20 patients undergoing multislice CT for pulmonary metastasis were reconstructed at 4.0, 2.0 and 0.75 mm RST and assessed by two blinded radiologists (R1 and R2) and CAD. Data were compared against an independent reference standard. Nodule subgroups (diameter >10, 4-10, <4 mm) were assessed separately. Statistical methods were the ROC analysis and Mann-Whitney U test. CAD was outperformed by readers at 4.0 mm (Az = 0.18, 0.62 and 0.69 for CAD, R1 and R2, respectively; P<0.05), comparable at 2.0 mm (Az = 0.57, 0.70 and 0.69 for CAD, R1 and R2, respectively), and superior using 0.75 mm RST (Az = 0.80, 0.70 and 0.70 and sensitivity = 0.74, 0.53 and 0.53 for CAD, R1 and R2, respectively; P<0.05). Reader performances were significantly enhanced by CAD (Az = 0.93 and 0.95 for R1 + CAD and R2 + CAD, respectively, P<0.05). The CAD advantage was best for nodules <10 mm (detection rates = 93.3, 89.9, 47.9 and 47.9% for R1 + CAD, R2 + CAD, R1 and R2, respectively). CAD using 0.75 mm RST outperformed radiologists in nodules below 10 mm in diameter and should be used to replace a second radiologist. CAD is not recommended for 4.0 mm RST.

Accidental small bowel perforation after antegrade femoral artery access for percutaneous thromboembolectomy and angioplasty.

PURPOSE: To report a rare complication of antegrade femoral access for percutaneous aspiration thromboembolectomy and transluminal angioplasty. CASE REPORT: A 73-year-old obese woman underwent antegrade femoral aspiration thromboembolectomy for lower limb arterial embolism. Fifteen hours later, she presented with acute abdomen and decreased hemoglobin. Computed tomography showed small bowel obstruction, incarcerated femoral hernia, and free peritoneal air and fluid suggesting bowel perforation. Emergent laparotomy revealed an incarcerated, perforated femoral bowel loop and 4-quadrant peritonitis. CONCLUSIONS: Femoral hernia injury is an exceptional complication of vascular interventions. Knowledge of this potential hazard may help to avoid its occurrence.

Computer-assisted detection of pulmonary nodules: performance evaluation of an expert knowledge-based detection system in consensus reading with experienced and inexperienced chest radiologists.

To evaluate the performance of experienced versus inexperienced radiologists in comparison and in consensus with an interactive computer-aided detection (CAD) system for detection of pulmonary nodules. Eighteen consecutive patients (mean age: 62.2 years; range 29-83 years) prospectively underwent routine 16-row multislice computed tomography (MSCT). Four blinded radiologists (experienced: readers 1, 2; inexperienced: readers 3, 4) assessed image data against CAD for pulmonary nodules. Thereafter, consensus readings of readers 1+3, reader 1+CAD and reader 3+CAD were performed. Data were compared against an independent gold standard. Statistical tests used to calculate interobserver agreement, reader performance and nodule size were Kappa, ROC and Mann-Whitney U. CAD and experienced readers outperformed inexperienced readers (Az=0.72, 0.71, 0.73, 0.49 and 0.50 for CAD, readers 1-4, respectively; P<0.05). Performance of reader 1+CAD was superior to single reader and reader 1+3 performances (Az=0.93, 0.72 for reader 1+CAD and reader 1+3 consensus, respectively, P<0.05). Reader 3+CAD did not perform superiorly to experienced readers or CAD (Az=0.79 for reader 3+CAD; P>0.05). Consensus of reader 1+CAD significantly outperformed all other readings, demonstrating a benefit in using CAD as an inexperienced reader replacement. It is questionable whether inexperienced readers can be regarded as adequate for interpretation of pulmonary nodules in consensus with CAD, replacing an experienced radiologist.