Renal artery assessment with nonenhanced steady-state free precession versus contrast-enhanced MR angiography

PURPOSE: To prospectively assess the diagnostic accuracy of nonenhanced three-dimensional (3D) steady-state free precession (SSFP) magnetic resonance (MR) angiography for detection of renal artery stenosis (RAS), with breath-hold contrast material-enhanced MR angiography performed as the reference standard. MATERIALS AND METHODS: The study was local ethics committee approved; all patients gave written informed consent. Fifty-three patients (30 male, 23 female; mean age, 58 years) with arterial hypertension and suspected of having RAS were examined with 1.5-T 3D SSFP renal MR angiography. Stenosis grade, maximal visible vessel length, and subjective image quality were compared. Sensitivity, specificity, accuracy, and negative predictive value (NPV) were calculated on artery-by-artery and patient-by-patient bases. The significance of the results was assessed with the paired two-sided t test for continuous variables and with the marginal homogeneity test for categorical variables. Cohen kappa statistics were used to estimate interobserver agreement. RESULTS: One hundred eight renal arteries with 20 significant (>or=50%) stenoses were detected with contrast-enhanced MR angiography. At artery-by-artery analysis, sensitivity, specificity, accuracy, and NPV of nonenhanced SSFP MR angiography for RAS detection were 100%, 93%, 94%, and 100%, respectively, for observer 1 and 95%, 95%, 95%, and 99%, respectively, for observer 2. Corresponding patient-by-patient values were 100%, 92%, 94%, and 100%, respectively, for observer 1 and 100%, 95%, 96%, and 100%, respectively, for observer 2. Overestimation of stenosis grade with SSFP MR angiography resulted in six and four false-positive findings for readers 1 and 2, respectively. Mean maximal visible lengths of the renal arteries were 69.9 mm at contrast-enhanced MR angiography and 61.1 mm at SSFP MR angiography (P<.001). Both techniques yielded good to excellent image quality. CONCLUSION: Slab-selective inversion-prepared 3D SSFP MR angiography had high sensitivity, specificity, accuracy, and NPV for RAS detection, without the need for contrast material. However, RAS severity was overestimated in some patients.

[ECG-gated chest CT angiography: value for atypical chest pain evaluation]

PURPOSE: The aim of this study was to evaluate ECG-gated whole chest CTA as a routine triage tool for patients with acute chest pain. MATERIAL AND METHODS: Whole chest CTA with retrospective ECG-gating was performed in 30 patients with acute atypical chest pain. The ten main segments of the coronary arteries, the pulmonary arteries, the aorta, and the myocardium (function, morphology) were independently analyzed by a resident and two senior radiologists. The inter-observer agreement between resident and senior radiologists was calculated. A final diagnosis was determined by consensus. RESULTS: Thirty patients were included. The coronary artery segments, myocardium and pulmonary arteries were considered analyzable in 84%, 90% and 97% of cases respectively. A final diagnosis for the cause of pain was retained in 19 patients: significant coronary artery stenosis (5), pulmonary embolus (5), aortic dissection (1), hypokinetic cardiomyopathy (2), lung parenchymal abnormalities (5), and hiatus hernia (1). Inter-observer agreement ranged from 0.76 to 1 between senior radiologists and from 0.76 to 1 between resident and senior radiologists. The average time of image interpretation ranged from 14 to 15 minutes. CONCLUSION: ECG-gated whole chest CT angiography appears as a promising tool for the evaluation of acute chest pain. Combined evaluation of appearance and function of the myocardium can reveal additional interesting information.

Leg ischemia: assessment with MR angiography and spectroscopy

PURPOSE: To prospectively determine reproducibility of magnetic resonance (MR) angiography and MR spectroscopy of deoxymyoglobin in assessment of collateral vessels and tissue perfusion in patients with critical limb ischemia (CLI) and to follow changes in patients undergoing intramuscular vascular endothelial growth factor (pVEGF)-C gene therapy, percutaneous transluminal angioplasty, supervised exercise training, or no therapy. MATERIALS AND METHODS: Study and gene therapy protocols were approved, and all patients gave written informed consent. To determine repeatability and reproducibility, seven patients underwent MR angiography and five underwent MR spectroscopy. The techniques were used to judge disease progress in 12 other patients with or without therapy: MR angiography to help determine change in visualization of collateral vessels and MR spectroscopy to help assess change in perfusion at proximal and distal calf levels. MR angiographic results were subjectively analyzed by three blinded readers. Intraobserver variability was expressed as 95% confidence interval (CI) (n=7); interobserver variability, as kappa statistic (n=15). Reexamination variability of MR spectroscopy was given as 95% CI for subsequent recovery times, and correlation with disease extent was calculated with Kendall taub rank correlation. Fisher-Yates test was used to correlate changes with pressure measurements and clinical course. RESULTS: Intraobserver and interobserver concordance was sensitive for detection of collateral vessels. Intraobserver agreement was 85.7% (95% CI: 42.1%, 99.6%). Interobserver agreement was high for small collateral vessels (kappa=0.74, P <.001) and fair for large collateral vessels (kappa=0.36, P=.002). MR spectroscopy was reproducible (95% CI: +/-26 seconds for proximal, +/-21 seconds for distal) and showed a correlation with disease extent (proximal calf, taub=0.84, P <.001; distal calf, taub=0.68, P=.04). Small collateral vessels increased over time (P=.04) but did not correlate with pressure measurements and clinical course. Recovery time correlated with clinical course (proximal calf, P=.03; distal calf, P=.005). CONCLUSION: MR angiography and MR spectroscopy of deoxymyoglobin can help document changes in visualization of collateral vessels and tissue perfusion in patients with CLI.

Detection of pulmonary emboli with CT angiography at reduced radiation exposure and contrast material volume: comparison of 80 kVp and 120 kVp protocols in a matched cohort

The detection rate of pulmonary emboli (PE) with computed tomography angiography (CTA) using either a standard or a low-dose protocol, combining reduced radiation exposure and iodine delivery rate, was retrospectively analyzed in a matched cohort of 120 patients.

High-resolution three-dimensional 3 T magnetic resonance angiography for the evaluation of experimental aneurysm in the rabbit

OBJECTIVE: The standard technique of two-dimensional intra-arterial digital subtraction angiography (2D-DSA) for the imaging of experimental rabbit aneurysms is invasive and has considerable surgical risks. Therefore, minimally invasive techniques ideally providing three-dimensional imaging for intervention planning and follow-up are needed. This study evaluates the feasibility and quality of three-dimensional 3-T magnetic resonance angiography (3D-3T-MRA) and compares 3D-3T-MRA with 2D-DSA in experimental aneurysms in the rabbit. METHOD: Three microsurgically created aneurysms in three rabbits were evaluated using 2D-DSA and 3D-3T-MRA. Imaging of the aneurysms was performed 2 weeks after creation using 2D-DSA and contrast-enhanced (CE) MRA. Measurements included aneurysm dome (length and width) and aneurysm neck. Aneurysm volumes were determined using CE-MRA. RESULTS: The measurements of the aneurysms' dimensions and the evaluation of vicinity vessels with both techniques showed a good correlation. The mean aneurysm length, aneurysm width and neck width measured with DSA (6.9, 4.1 and 2.8 mm, respectively) correlated with the measurements performed in 3D-3T-MRA (6.9, 4 and 2.5 mm, respectively). The mean aneurysm volumes measured with CE-MRA was 46.7 mm(3). CONCLUSION: 3D-3T CE-MRA is feasible and less invasive and is a safer imaging alternative to DSA for experimental aneurysm. Additionally, aneurysm technique this precise offers the possibility of repetitive 3D aneurysm volumetry for long-term follow-up studies after endovascular aneurysm occlusion.

MR angiography of infrapopliteal arteries in patients with peripheral arterial occlusive disease by using Gadofosveset at 3.0 T: diagnostic accuracy compared with selective DSA

To prospectively compare the diagnostic accuracy of steady-state, high-spatial-resolution magnetic resonance (MR) angiography of the lower leg, performed with a blood pool contrast agent, with selective digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial disease.

Thoracoabdominal-aortoiliac multidetector-row CT angiography at 80 and 100 kVp: assessment of image quality and radiation dose

OBJECTIVE: To compare image quality and radiation dose of thoracoabdominal computed tomography (CT) angiography at 80 and 100 kVp and to assess the feasibility of reducing contrast medium volume from 60 to 45 mL at 80 kVp. MATERIALS AND METHODS: This retrospective study had institutional review board approval; informed consent was waived. Seventy-five patients who had undergone thoracoabdominal 64-section multidetector-row CT angiography were divided into 3 groups of 25 patients each. Patients of groups A (tube voltage, 100 kVp) and B (tube voltage, 80 kVp) received 60 mL of contrast medium at 4 mL/s. Patients of group C (tube voltage, 80 kVp) received 45 mL of contrast medium at 3 mL/s. Mean aortoiliac attenuation, image noise, and contrast-to-noise ratio were assessed. The measurement of radiation dose was based on the volume CT dose index. Three independent readers assessed the diagnostic image quality. RESULTS: Mean aortoiliac attenuation for group B (621.1 +/- 90.5 HU) was significantly greater than for groups A and C (485.2 +/- 110.5 HU and 483.1 +/- 119.8 HU; respectively) (P < 0.001). Mean image noise was significantly higher for groups B and C than for group A (P < 0.05). The contrast-to-noise ratio did not significantly differ between the groups (group A, 35.0 +/- 13.8; group B, 31.7 +/- 10.1; group C, 27.3 +/- 11.5; P = 0.08). Mean volume CT dose index in groups B and C (5.2 +/- 0.4 mGy and 4.9 +/- 0.3 mGy, respectively) were reduced by 23.5% and 27.9%, respectively, compared with group A (6.8 +/- 0.8 mGy) (P < 0.001). The average overall diagnostic image quality for the 3 groups was graded as good or better. The score for group A was significantly higher than that for group C (P < 0.01), no difference was seen between group A and B (P = 0.92). CONCLUSIONS: Reduction of tube voltage from 100 to 80 kVp for thoracoabdominal CT angiography significantly reduces radiation dose without compromising image quality. Reduction of contrast medium volume to 45 mL at 80 kVp resulted in lower but still diagnostically acceptable image quality.

Is body weight the most appropriate criterion to select patients eligible for low-dose pulmonary CT angiography? Analysis of objective and subjective image quality at 80 kVp in 100 patients

The objective of this retrospective study was to assess image quality with pulmonary CT angiography (CTA) using 80 kVp and to find anthropomorphic parameters other than body weight (BW) to serve as selection criteria for low-dose CTA. Attenuation in the pulmonary arteries, anteroposterior and lateral diameters, cross-sectional area and soft-tissue thickness of the chest were measured in 100 consecutive patients weighing less than 100 kg with 80 kVp pulmonary CTA. Body surface area (BSA) and contrast-to-noise ratios (CNR) were calculated. Three radiologists analyzed arterial enhancement, noise, and image quality. Image parameters between patients grouped by BW (group 1: 0-50 kg; groups 2-6: 51-100 kg, decadally increasing) were compared. CNR was higher in patients weighing less than 60 kg than in the BW groups 71-99 kg (P between 0.025 and <0.001). Subjective ranking of enhancement (P = 0.165-0.605), noise (P = 0.063), and image quality (P = 0.079) did not differ significantly across all patient groups. CNR correlated moderately strongly with weight (R = -0.585), BSA (R = -0.582), cross-sectional area (R = -0.544), and anteroposterior diameter of the chest (R = -0.457; P < 0.001 all parameters). We conclude that 80 kVp pulmonary CTA permits diagnostic image quality in patients weighing up to 100 kg. Body weight is a suitable criterion to select patients for low-dose pulmonary CTA.

Endoleak detection with CT angiography in an abdominal aortic aneurysm phantom: effect of tube energy, simulated patient size, and physical properties of endoleaks

To analyze the detection of endoleaks with low-tube-voltage computed tomographic (CT) angiography.

Effect of automatic tube current modulation on radiation dose and image quality for low tube voltage multidetector row CT angiography: phantom study

RATIONALE AND OBJECTIVES: To evaluate the effect of automatic tube current modulation on radiation dose and image quality for low tube voltage computed tomography (CT) angiography. MATERIALS AND METHODS: An anthropomorphic phantom was scanned with a 64-section CT scanner using following tube voltages: 140 kVp (Protocol A), 120 kVp (Protocol B), 100 kVp (Protocol C), and 80 kVp (Protocol D). To achieve similar noise, combined z-axis and xy-axes automatic tube current modulation was applied. Effective dose (ED) for the four tube voltages was assessed. Three plastic vials filled with different concentrations of iodinated solution were placed on the phantom's abdomen to obtain attenuation measurements. The signal-to-noise ratio (SNR) was calculated and a figure of merit (FOM) for each iodinated solution was computed as SNR(2)/ED. RESULTS: The ED was kept similar for the four different tube voltages: (A) 5.4 mSv +/- 0.3, (B) 4.1 mSv +/- 0.6, (C) 3.9 mSv +/- 0.5, and (D) 4.2 mSv +/- 0.3 (P > .05). As the tube voltage decreased from 140 to 80 kVp, image noise was maintained (range, 13.8-14.9 HU) (P > .05). SNR increased as the tube voltage decreased, with an overall gain of 119% for the 80-kVp compared to the 140-kVp protocol (P < .05). The FOM results indicated that with a reduction of the tube voltage from 140 to 120, 100, and 80 kVp, at constant SNR, ED was reduced by a factor of 2.1, 3.3, and 5.1, respectively, (P < .001). CONCLUSIONS: As tube voltage decreases, automatic tube current modulation for CT angiography yields either a significant increase in image quality at constant radiation dose or a significant decrease in radiation dose at a constant image quality.

Multifocal posterior uveitis in Crohn's disease

PURPOSE To report a case of rare posterior eye manifestation of Crohn's disease preceding recurrence of inflammatory bowel disease. METHODS Case report with ophthalmoscopic findings, fluorescein/indocyanin green angiograms, automated perimetry and multifocal-ERG. RESULTS The perimetry revealed absolute and relative scotomas corresponding to multifocal inflammatory lesions in the retina and choroid, reduced a/b amplitudes in multifocal-ERG and hypofluorescent dots in angiography. Under oral prednisolone visual defects, ophthalmoscopic and angiographic findings resolved, while a/b amplitudes remained mildly reduced. The ocular changes occurred without systemic hypertension and were followed by a new episode of intestinal symptoms. CONCLUSION Multifocal inflammatory lesions in the retina and choroid in patients with Crohn's disease may occur and may precede a recurrent intestinal episode. Crohn's patients should be carefully followed up in collaboration with internal medicine specialists.

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.

Evaluation of 9 biomarkers for predicting 10-year cardiovascular risk in patients undergoing coronary angiography: findings from the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study.

BACKGROUND Conventional factors do not fully explain the distribution of cardiovascular outcomes. Biomarkers are known to participate in well-established pathways associated with cardiovascular disease, and may therefore provide further information over and above conventional risk factors. This study sought to determine whether individual and/or combined assessment of 9 biomarkers improved discrimination, calibration and reclassification of cardiovascular mortality. METHODS 3267 patients (2283 men), aged 18-95 years, at intermediate-to-high-risk of cardiovascular disease were followed in this prospective cohort study. Conventional risk factors and biomarkers were included based on forward and backward Cox proportional stepwise selection models. RESULTS During 10-years of follow-up, 546 fatal cardiovascular events occurred. Four biomarkers (interleukin-6, neutrophils, von Willebrand factor, and 25-hydroxyvitamin D) were retained during stepwise selection procedures for subsequent analyses. Simultaneous inclusion of these biomarkers significantly improved discrimination as measured by the C-index (0.78, P = 0.0001), and integrated discrimination improvement (0.0219, P<0.0001). Collectively, these biomarkers improved net reclassification for cardiovascular death by 10.6% (P<0.0001) when added to the conventional risk model. CONCLUSIONS In terms of adverse cardiovascular prognosis, a biomarker panel consisting of interleukin-6, neutrophils, von Willebrand factor, and 25-hydroxyvitamin D offered significant incremental value beyond that conveyed by simple conventional risk factors.

Cystatin C is independently associated with total and cardiovascular mortality in individuals undergoing coronary angiography. The Ludwigshafen Risk and Cardiovascular Health (LURIC) study.

AIMS Cystatin C is a well established marker of kidney function. There is evidence that cystatin C concentrations are also associated with mortality. The present analysis prospectively evaluated the associations of cystatin C with all-cause and cardiovascular (CV) mortality in a well-characterized cohort of persons undergoing angiography, but without overt renal insufficiency. METHODS Cystatin C was available in 2998 persons (mean age: 62.7 ± 10.5 years; 30.3% women). Of those 2346 suffered from coronary artery disease (CAD) and 652 (controls) did not. Creatinine (mean ± SD: 83.1 ± 47.8 vs. 74.1 ± 24.7 μmol/L, p = 0.036) but not Cystatin C (mean ± SD: 1.02 ± 0.44 vs. 0.92 ± 0.26 mg/L, p = 0.065) was significantly higher in patients with CAD. After a median follow-up of 9.9 years, in total 898 (30%) deaths occurred, 554 (18.5%) due to CV disease and 326 (10.9%) due to non-CV causes. Multivariable-adjusted Cox analysis (adjusting for eGFR and established cardiovascular risk factors, lipid lowering therapy, angiographic coronary artery disease, and C-reactive protein) revealed that patients in the highest cystatin C quartile were at an increased risk for all-cause (hazard ratio (HR) 1.93, 95% CI 1.50-2.48) and CV mortality (HR 2.05 95% CI 1.48-2.84) compared to those in the lowest quartile. The addition of cystatin C to a model consisting of established cardiovascular risk factors increased the area under the receiver-operating characteristic curve for CV and all-cause mortality, but the difference was statistically not significant. However, reclassification analysis revealed significant improvement by addition of cystatin C for CV and all-cause mortality (p < 0.001), respectively. CONCLUSION The concentration of cystatin C is strongly associated with long-term all-cause and cardiovascular mortality in patients referred to coronary angiography, irrespective of creatinine-based renal function.

True four-dimensional analysis of thoracic aortic displacement and distension using model-based segmentation of computed tomography angiography.

Previous analyses of aortic displacement and distension using computed tomography angiography (CTA) were performed on double-oblique multi-planar reformations and did not consider through-plane motion. The aim of this study was to overcome this limitation by using a novel computational approach for the assessment of thoracic aortic displacement and distension in their true four-dimensional extent. Vessel segmentation with landmark tracking was executed on CTA of 24 patients without evidence of aortic disease. Distension magnitudes and maximum displacement vectors (MDV) including their direction were analyzed at 5 aortic locations: left coronary artery (COR), mid-ascending aorta (ASC), brachiocephalic trunk (BCT), left subclavian artery (LSA), descending aorta (DES). Distension was highest for COR (2.3 ± 1.2 mm) and BCT (1.7 ± 1.1 mm) compared with ASC, LSA, and DES (p < 0.005). MDV decreased from COR to LSA (p < 0.005) and was highest for COR (6.2 ± 2.0 mm) and ASC (3.8 ± 1.9 mm). Displacement was directed towards left and anterior at COR and ASC. Craniocaudal displacement at COR and ASC was 1.3 ± 0.8 and 0.3 ± 0.3 mm. At BCT, LSA, and DES no predominant displacement direction was observable. Vessel displacement and wall distension are highest in the ascending aorta, and ascending aortic displacement is primarily directed towards left and anterior. Craniocaudal displacement remains low even close to the left cardiac ventricle.