Coronary 64-slice CT angiography predicts outcome in patients with known or suspected coronary artery disease

The aim of this study was to assess the prognostic value of 64-slice CT angiography (CTA) in patients with known or suspected coronary artery disease (CAD). Sixty-four-slice coronary CTA was performed in 220 patients [mean age 63 ± 11 years, 77 (35%) female] with known or suspected CAD. CTA images were analyzed with regard to the presence and number of coronary lesions. Patients were followed-up for the occurrence of the following clinical endpoints: death, nonfatal myocardial infarction, unstable angina, and coronary revascularization. During a mean follow-up of 14 ± 4 months, 59 patients (27%) reached at least one of the predefined clinical endpoints. Patients with abnormal coronary arteries on CTA (i.e., presence of coronary plaques) had a 1st-year event rate of 34%, whereas in patients with normal coronary arteries no events occurred (event rate, 0%, p < 0.001). Similarly, obstructive lesions (≥50% luminal narrowing) on CTA were associated with a high first-year event rate (59%) compared to patients without stenoses (3%, p < 0.001). The presence of obstructive lesions was a significant independent predictor of an adverse cardiac outcome. Sixty-four-slice CTA predicts cardiac events in patients with known or suspected CAD. Conversely, patients with normal coronary arteries on CTA have an excellent mid-term prognosis.     

Carotid stenosis degree in CT angiography: assessment based on luminal area versus luminal diameter measurements

The aim of this study was to investigate CT angiography (CTA) luminal area measurements in the assessment of carotid artery stenosis compared with the current clinically used criteria based on lumen diameter measurements. Seventy-two vessels in 36 patients were evaluated by CTA and digital subtraction angiography (DSA). Two observers measured area and diameter stenosis degrees using automated 3D CTA analysis software. The ratio of the largest/smallest luminal diameter at the level of maximal stenosis (L/S ratio) was used to describe lumen morphology. Diagnostic agreement between CTA and DSA was calculated. For the assessment of area stenosis, interobserver and intraobserver correlation coefficients were 0.898 and 0.906 (p<0.001). The correlation coefficient between the diameter stenosis and area stenosis was lower in stenoses with extremely noncircular lumen (L/S ratio 1.5) (r=0.797, p<0.001) compared with stenoses with circular lumen (LS ratio <1.2) (r=0.978, p<0.001). Only satisfactory agreement ( 0.54-0.77, p<0.001) was obtained between area stenosis on CTA and diameter stenosis on DSA. Assessment of stenosis degree with area measurements on 3D CTA proved to be reproducible. Area stenosis provides a less-severe estimate of the degree of carotid stenosis but might theoretically express the real hemodynamic significance of the lesion better than diameter stenosis, especially in stenoses with noncircular lumen.     

Calcification remodeling index assessed by cardiac CT predicts severe coronary stenosis in lesions with moderate to severe calcification

ObjectivesTo assess the diagnostic performance of the calcification remodeling index (RI) as assessed by coronary computed tomography angiography (coronary CTA) to predict the presence of severe coronary stenosis in atherosclerotic coronary lesions with moderate to severe calcification.MethodsPatients who underwent coronary CTA and invasive coronary angiography (ICA) within one month and had moderately to severely calcified lesions as revealed by coronary CTA, were retrospectively included. The calcification RI was calculated as the ratio of the cross-sectional lumen area (with inclusion of calcium area) of the most severely calcified site to the proximal reference lumen area. Other parameters, such as the calcium volume, regional Agatston score, calcification length, involved calcium arc quadrants and CTA-assessed diameter stenosis, were also recorded. A multivariate model was used to identify the variables that predict the presence of severe coronary stenosis (diameter stenosis ≧ 70%) as determined by ICA.Results422 patients with 629 lesions were finally included in the study. Lesions with severe stenoses as determined by ICA tended to have larger calcium volumes, regional Agatston scores, CTA-assessed diameter stenoses, longer calcium length, more involved calcium arc quadrants and a significantly smaller calcification remodeling index. ROC curve analysis determined the best cutoff value of the calcification RI as 0.94 (AUC = 0.816, p < 0.001), which yielded highest diagnostic accuracy (83.3%, 524/629) to identify severe coronary stenosis. Among all parameters, calcification RI ≦0.94 is the strongest independent predictor (odds ratio: 17.5, p < 0.001) of severe coronary stenosis.ConclusionsWith an optimalcut-off value of 0.94, calcification RI is the strongest independent predictor of severe coronary stenosis in calcified coronary atherosclerotic lesions.     

Validation of a new cardiac image fusion software for three-dimensional integration of myocardial perfusion SPECT and stand-alone 64-slice CT angiography

Purpose Combining the functional information of SPECT myocardial perfusion imaging (SPECT-MPI) and the morphological information of coronary CT angiography (CTA) may allow easier evaluation of the spatial relationship between coronary stenoses and perfusion defects. The aim of the present study was the validation of a novel software solution for three-dimensional (3D) image fusion of SPECT-MPI and CTA. Methods SPECT-MPI with adenosine stress/rest ^99mTc-tetrofosmin was fused with 64-slice CTA in 15 consecutive patients with a single perfusion defect and a single significant coronary artery stenosis (≥50% diameter stenosis). 3D fused SPECT/CT images were analysed by two independent observers with regard to superposition of the stenosed vessel onto the myocardial perfusion defect. Interobserver variability was assessed by recording the X, Y, Z coordinates for the origin of the stenosed coronary artery and the centre of the perfusion defect and measuring the distance between the two landmarks. Results SPECT-MPI revealed a fixed defect in seven patients, a reversible defect in five patients and a mixed defect in three patients and CTA documented a significant stenosis in the respective subtending coronary artery. 3D fused SPECT/CT images showed a match of coronary lesion and perfusion defect in each patient and the fusion process took less than 15 min. Interobserver variability was excellent for landmark detection (r = 1.00 and r = 0.99, p < 0.0001) and very good for the 3D distance between the two landmarks (r = 0.94, p < 0.001). Conclusion 3D SPECT/CT image fusion is feasible, reproducible and allows correct superposition of SPECT segments onto cardiac CT anatomy.     

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 × 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%. David Maintz and Matthias Burg contributed equally to this publication.     

Sixty-four-slice computed tomography coronary angiography compared with myocardial perfusion scintigraphy for the diagnosis of functionally significant coronary stenoses in patients with a low to intermediate likelihood of coronary artery disease

Background. Multislice computed tomography coronary angiography (CTA) was proposed as a method for investigating possible coronary artery disease (CAD) in patients who present with chest pain but with a low to intermediate likelihood of CAD. Sixty-four-channel CTA was compared prospectively with ^99mTc-tetrofosmin myocardial perfusion scintigraphy (MPS) (as the gold standard in the detection of flow-limiting stenoses) for the detection of functionally significant CAD. Methods and Results. Fifty-two consecutive symptomatic patients with a low to intermediate likelihood of coronary artery disease, and who were referred for MPS, also underwent CTA. The CTA datasets were analyzed by two experienced observers who were blinded to the MPS data, and coronary artery segments were reported as <50%, 50% to 69%, 70% to 99% stenoses, or occluded. The MPS images were similarly analyzed for inducible perfusion abnormalities, and coronary territories were identified. At the patient level, agreement between CTA and MPS for CTA lesions at ≥50% was 87% (sensitivity, 100%; specificity, 84%; positive predictive value, 50%; negative predictive value, 100%). For CTA lesions, agreement at ≥70% was 96% (sensitivity, 86%; specificity, 98%; positive predictive value, 86%; negative predictive value, 98%). Conclusions. In patients with a low to intermediate likelihood of CAD, there is good correlation between MPS and CTA for the detection of functionally significant coronary artery stenoses when CTA detects a narrowing of ≥70% severity. Computed tomography coronary angiography stenoses of 70% should be used to determine functional significance, and not 50%, as is the usual practice at present. This work was funded by an unrestricted research grant from the United Kingdom Defence Postgraduate Medical Deanery. We also thank the Royal Air Force Medical Branch for financial support.     

Accuracy of 64-slice CT angiography for the detection of functionally relevant coronary stenoses as assessed with myocardial perfusion SPECT

Purpose CT angiography (CTA) offers a valuable alternative for the diagnosis of CAD but its value in the detection of functionally relevant coronary stenoses remains uncertain. We prospectively compared the accuracy of 64-slice CTA with that of myocardial perfusion imaging (MPI) using ^99mTc-tetrofosmin-SPECT as the gold standard for the detection of functionally relevant coronary artery disease (CAD). Methods MPI and 64-slice CT were performed in 100 consecutive patients. CTA lesions were analysed quantitatively and area stenoses ≥50% and ≥75% were compared with the MPI findings. Results In 23 patients, MPI perfusion defects were found (12 reversible, 13 fixed). A total of 399 coronary arteries and 1,386 segments was analysed. Eighty-four segments (6.1%) in 23 coronary arteries (5.8%) of nine patients (9.0%) were excluded owing to insufficient image quality. In the remaining 1,302 segments, quantitative CTA revealed stenoses ≥50% in 57 of 376 coronary arteries (15.2%) and stenoses ≥75% in 32 (8.5%) coronary arteries. Using a cut-off at ≥75% area stenosis, CTA yielded the following sensitivity, specificity, negative (NPV) and positive predictive value (PPV), and accuracy for the detection of any (fixed and reversible) MPI defect: by patient, 75%, 90%, 93%, 68% and 87%, respectively; by artery, 76%, 95%, 99%, 50% and 94%, respectively. Conclusion Sixty-four-slice CTA is a reliable tool to rule out functionally relevant CAD in a non-selected population with an intermediate pretest likelihood of disease. However, an abnormal CTA is a poor predictor of ischaemia.     

Imaging coronary and extracoronary atherosclerosis: feasibility and impact of whole-body computed tomography angiography

A comprehensive whole-body approach to noninvasive evaluation of coronary and extracoronary vasculature is currently not available. The objective of our study was to assess the potential of 64-slice computed tomography angiography (64-CTA) for whole-body evaluation of atherosclerosis burden. Seventy-eight patients referred for coronary imaging underwent whole-body 64-CTA using an adjusted strategy for the administration of contrast medium with dose-saving algorithms involving ECG modulation and reduced tube voltage. Arterial segments (15 coronary, 32 systemic) were evaluated for significant (≥50%) steno-occlusive disease while arterovenous density was evaluated at seven extracoronary locations. Homogeneous attenuation (mean 321 ± 20 HU) was obtained throughout the systemic vasculature. Atherosclerosis was observed in 238/995 (24%) coronary and 368/2441 (15%) systemic segments. Significant stenoses/occlusions were present in 214 (21%)/24 (2.5%) coronary segments while asymptomatic clinically relevant stenoses were present in 49 systemic segments. Sensitivity, specificity, positive and negative predictive values of coronary 64-CTA among 52 patients who also underwent quantitative coronary angiography were 92%, 95%, 81% and 98%, respectively. ECG modulation decreased radiation exposure to 14.1–15.4 mSv per patient. Comprehensive, noninvasive assessment of atherosclerosis can be performed by whole-body 64-CTA and may have a positive impact on secondary prevention.     

Asymmetry of intracranial internal carotid artery on 3D TOF MR angiography: a sign of unilateral extracranial stenosis

The purpose of this case-control study was to determine whether an asymmetry of size of the intracranial internal carotid artery (ICA) on 3D time-of-flight MR angiography (MRA) is predictive of a high-grade cervical ICA stenosis. Ninety-six stroke/TIA consecutive patients were recruited for the study, of whom 32 had unilateral high-grade ICA stenosis (≥70% NASCET) and were included into the case group, and the remaining 64 did not have such high-grade stenosis and were included in the control group. On intracranial MRA, two observers, blinded to the characteristics of cervical ICA stenosis, independently searched for qualitative size asymmetry between ICAs and measured the cross-sectional surface of the intracranial ICAs. An intracranial size asymmetry was seen in 28 of the 32 high-grade stenoses by both readers, and in 10 (reader₁) and 8 (reader₂) of the 64 controls (sensitivity = 88%, specificity = 84–88%). In patients without agenesia of the A1 segment of the circle of Willis (n = 70), sensitivity was ≥90% and specificity = 96%. Surfaces ratios were significantly different (p < 0.001) between cases and controls. However, using ROC curves analysis, the quantitative processing did not improve the detection when compared with the qualitative assessment of intracranial ICA asymmetry. A size asymmetry of the intracranial ICAs reveals the presence of an underlying high-grade cervical stenosis, with a high degree of confidence, especially in patients without anatomical variant of the anterior part of the circle of Willis. This sign may allow an early detection of high-grade cervical carotid stenosis in stroke patients before dedicated neck imaging is performed.     

Computed tomographic coronary angiography in patients with surgically treated type A aortic dissection: preliminary results

Acute type A aortic dissection is a serious emergency with a mortality rate of up to 40% within the first 24 h when left untreated. Surgical therapy needs to be initiated promptly. Due to this urgent situation, preoperative evaluation of the coronary arteries is not routinely performed in these patients. The aim of this study was to evaluate the accuracy of 64-slice computed tomography angiography (CTA) for postoperative coronary artery assessment in these patients. Ten consecutive patients with two or more cardiovascular risk factors were prospectively enrolled. Patients had type A aortic dissection treated surgically with a supracoronary graft of the ascending aorta. Performance of CTA to exclude significant stenosis (>50% lumen narrowing) and/or coronary artery dissection was compared with quantitative coronary angiography. A total of 147 segments were evaluated. Three segments (2%) were excluded from analysis. CTA correctly assessed one of three significant stenoses in three patients and correctly excluded coronary artery disease (CAD) in six of ten patients. One patient was rated false positive. Overall accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT for identifying coronary artery disease by segment was 98%, 33%, 99%, 50%, and 99%, respectively (P < 0.05). By patient, it was 70%, 33%, 86%, 50%, and 75%, respectively. No coronary artery dissection was found. Noninvasive CTA may be a viable alternative to conventional angiography for postoperative coronary artery evaluation in patients with surgically treated type A aortic dissection and cardiovascular risk factors. An NPV of 99% should allow for reliable exclusion of CAD. Further studies with higher patient numbers are warranted.     

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.     

Remodelling of the aortic root in severe tricuspid aortic stenosis: implications for transcatheter aortic valve implantation

Detailed knowledge of aortic root geometry is a prerequisite to anticipate complications of transcatheter aortic valve (TAV) implantation. We determined coronary ostial locations and aortic root dimensions in patients with aortic stenosis (AS) and compared these values with normal subjects using computed tomography (CT). One hundred consecutive patients with severe tricuspid AS and 100 consecutive patients without valvular pathology (referred to as the controls) undergoing cardiac dual-source CT were included. Distances from the aortic annulus (AA) to the left coronary ostium (LCO), right coronary ostium (RCO), the height of the left coronary sinus (HLS), right coronary sinus (HRS), and aortic root dimensions [diameters of AA, sinus of Valsalva (SV), and sino-tubular junction(STJ)] were measured. LCO and RCO were 14.9 ± 3.2 mm (8.2–25.9) and 16.8 ± 3.6 mm (12.0–25.7) in the controls, 15.5 ± 2.9 mm (8.8–24.3) and 17.3 ± 3.6 mm (7.3–26.0) in patients with AS. Controls and patients with AS had similar values for LCO (P = 0.18), RCO (P = 0.33) and HLS (P = 0.88), whereas HRS (P < 0.05) was significantly larger in patients with AS. AA (r = 0.55,P < 0.001), SV (r = 0.54,P < 0.001), and STJ (r = 0.52,P < 0.001) significantly correlated with the body surface area in the controls; whereas no correlation was found in patients with AS. Patients with AS had significantly larger AA (P < 0.01) and STJ (P < 0.01) diameters when compared with the controls. In patients with severe tricuspid AS, coronary ostial locations were similar to the controls, but a transverse remodelling of the aortic root was recognized. Owing to the large distribution of ostial locations and the dilatation of the aortic root, CT is recommended before TAV implantation in each patient.     

Coronary artery stent geometry and in-stent contrast attenuation with 64-slice computed tomography

We aimed at assessing stent geometry and in-stent contrast attenuation with 64-slice CT in patients with various coronary stents. Twenty-nine patients (mean age 60 ± 11 years; 24 men) with 50 stents underwent CT within 2 weeks after stent placement. Mean in-stent luminal diameter and reference vessel diameter proximal and distal to the stent were assessed with CT, and compared to quantitative coronary angiography (QCA). Stent length was also compared to the manufacturer’s values. Images were reconstructed using a medium-smooth (B30f) and sharp (B46f) kernel. All 50 stents could be visualized with CT. Mean in-stent luminal diameter was systematically underestimated with CT compared to QCA (1.60 ± 0.39 mm versus 2.49 ± 0.45 mm; P < 0.0001), resulting in a modest correlation of QCA versus CT (r = 0.49; P < 0.0001). Stent length as given by the manufacturer was 18.2 ± 6.2 mm, correlating well with CT (18.5 ± 5.7 mm; r = 0.95; P < 0.0001) and QCA (17.4 ± 5.6 mm; r = 0.87; P < 0.0001). Proximal and distal reference vessel diameters were similar with CT and QCA (P = 0.06 and P = 0.03). B46f kernel images showed higher image noise (P < 0.05) and lower in-stent CT attenuation values (P < 0.001) than images reconstructed with the B30f kernel. 64-slice CT allows measurement of coronary artery in-stent density, and significantly underestimates the true in-stent diameter compared to QCA. Philipp A. Kaufmann was supported by a grant from the Swiss National Science Foundation (SNSF-professorship grant No. PP00A-68835). Hatem Alkadhi and Lotus Desbiolles were supported by the National Center of Competence in Research, Computer Aided and Image Guided Medical Interventions (NCCR CO-ME) of the Swiss National Science Foundation.     

Contrast-enhanced cardiac MRI before coronary artery bypass surgery: impact of myocardial scar extent on bypass flow

The aim of the study was to relate the extent of myocardial late gadolinium enhancement (LGE) in cardiac MRI to intraoperative graft flow in patients undergoing coronary artery bypass graft (CABG) surgery. Thirty-three CAD patients underwent LGE MRI before surgery using an inversion-recovery GRE sequence (turboFLASH). Intraoperative graft flow in Doppler ultrasonography was compared with the scar extent in each coronary vessel territory. One hundred and fourteen grafts were established supplying 86 of the 99 vessel territories. A significant negative correlation was found between scar extent and graft flow (r = −0.4, p < 0.0001). Flow in grafts to territories with no or small subendocardial scar was significantly higher than in grafts to territories with broad nontransmural or transmural scar (75 ± 39 vs. 38 ± 26 cc min⁻¹; p < 0.0001). In summary, the extent of myocardial scar as defined by contrast-enhanced MRI predicts coronary bypass graft flow. Beyond the probability of functional recovery, preoperative MRI might add value to surgery planning by predicting midterm bypass graft patency.     

Multislice computed tomography angiography of the abdominal arteries: comparison between computed tomography angiography and digital subtraction angiography findings in 52 cases

Since the introduction of multislice CT scanners, CT angiography (CTA) has become a powerful tool for imaging the vascular system. We compare conventional angiography to CTA in the diagnosis of morphological changes in the abdominal aorta and its branches. A retrospective analysis of 52 patients who underwent both multislice CT angiography (MSCTA) and digital subtraction angiography before surgical treatment is presented. All CT examinations were performed after administration of 100 mL contrast medium with a collimation of 4 x 1 mm and a pitch of 7. A standardized evaluation of the axial, multiplanar and 3D reconstructions was performed by two experienced radiologists. Stenoses were classified as high-grade and low-grade, and aneurysms, occlusions and arteriosclerosis were evaluated. The CTA findings were compared with conventional angiography. All aneurysms, occlusions, stenoses and calcifications were diagnosed correctly by CTA in axial and multiplanar projections (sensitivity 1.0; specificity 1.0). The degree of stenosis was overestimated in three cases when using axial projections. Three-dimensional volume-rendered CTA showed a sensitivity of 0.91 for aneurysms, 0.82 for stenoses, 0.75 for occlusions and 0.77 for calcifications. The specificity was 1.0 in all cases. Multislice CT angiography seems to be similar to conventional digital subtraction angiography for abdominal vessels if multiplanar projections are used.     

Correlation of volumetric mismatch and mismatch of Alberta Stroke Program Early CT Scores on CT perfusion maps

Introduction  We aimed to determine if volumetric mismatch between tissue at risk and tissue destined to infarct on computed tomography perfusion (CTP) can be described by the mismatch of Alberta Stroke Program Early CT Score (ASPECTS). Materials and methods  Forty patients with nonlacunar middle cerebral artery infarct <6 h old who had CTP on admission were retrospectively reviewed. Two raters segmented the lesion volume on mean transit time (MTT) and cerebral blood volume (CBV) maps using thresholds of >6 s and <2.0 mL per 100 g, respectively. Two other raters assigned ASPECTS to the same MTT and CBV maps while blinded to the volumetric data. Volumetric mismatch was deemed present if ≥20%. ASPECTS mismatch (=CBV ASPECTS − MTT ASPECTS) was deemed present if ≥1. Correlation between the two types of mismatches was assessed by Spearman’s coefficient (ρ). ROC curve analyses were performed to determine the optimal ASPECTS mismatch cut point for volumetric mismatch ≥20%, ≥50%, ≥100%, and ≥150%. Results  Median volumetric mismatch was 130% (range 10.9–2,031%) with 31 (77.5%) being ≥20%. Median ASPECTS mismatch was 2 (range 0–6) with 26 (65%) being ≥1. ASPECTS mismatch correlated strongly with volumetric mismatch with ρ = 0.763 [95% CI 0.585–0.870], p < 0.0001. Sensitivity and specificity for volumetric mismatch ≥20% was 83.9% [95% CI 65.5–93.5] and 100% [95% CI 65.9–100], respectively, using ASPECTS mismatch ≥1. Volumetric mismatch ≥50%, ≥100%, and ≥150% were optimally identified using ASPECTS mismatch ≥1, ≥2, and ≥2, respectively. Conclusion  On CTP, ASPECTS mismatch showed strong correlation to volumetric mismatch. ASPECTS mismatch ≥1 was the optimal cut point for volumetric mismatch ≥20%.     

Clinical usefulness of novel cardiac MDCT/SPECT fusion image

Background  We evaluated the relationship between computed tomography angiography (CTA) and SPECT, and assessed to determine the clinical usefulness of the fusion image using CTA and myocardial perfusion imaging (MPI). Methods  Forty-one consecutive patients [after coronary artery bypass operation (n = 13) and suspected stenosis (n = 28)] underwent MPI and CTA. SPECT/CTA fused images were generated. Results  In total, 687 segments including bypass graft in 164 coronary arteries were analyzed. Myocardial ischemia on MPI was observed in 11 patients among 28 with CTA abnormalities, one had both ischemia and infarction, and 7 had only infarction. Segment-based analysis showed that ischemia was found in 14 segments (24%) among 59 stenoses on CTA. Forty stenotic segments (69%) were not associated with perfusion abnormality. The rest 5 stenotic segments were considered equivocal (8%). A fusion image made it possible to associate perfusion defects with its corresponding coronary artery in 4 out of 5 equivocal lesions on side-by-side analysis. Patients with incremental diagnostic information on SPECT/CTA fusion (n = 4) had significant smaller coronary diameter than that of not-improved coronary vessels (2.0 ± 0.4 vs. 3.9 ± 0.4 mm, p = 0.001). Conclusion  Cardiac fusion imaging accurately diagnosed functionally relevant coronary stenosis. SPECT/CTA fusion images in coronary artery disease may provide added diagnostic information on functional relevance of coronary artery disease.     

CT angiography of the common carotid artery bifurcation: comparison between two techniques and conventional angiography

We prospectively compared CT angiography (CTA) of the common carotid artery bifurcation using two different techniques with conventional angiography in patients with suspected stenoses of the internal carotid arteries in 20 symptomatic patients. Ten patients (Group 1) received 60 cc of contrast (medium 2 cc/sec) and CTA was acquired using 5 mm slices, reconstructed at 3 mm slice thickness. Ten patients (Group 2) received 90 cc of contrast (medium 3 cc/sec) and CTA was acquired using 3 mm slices reconstructed at 1 mm slice thickness. All CTA studies were postprocessed using maximum intensity projection algorithm. Stenoses were graded prospectively from CT angiograms and compared with selective conventional catheter angiograms. In Group 1, CTA overestimated the degree of narrowing in 9 of 10 stenoses proven by conventional angiograms. We interpreted 2 nearly occluded internal carotid arteries, 2 with moderate and marked stenoses, and 2 with no narrowings, but fibromuscular dysplasia on conventional angiograms as occluded on CTA, and 3 vessels as showing marked stenoses, not confirmed by angiography. CTA clearly depicted 1 mild stenosis, 4 normal bifurcations, and 6 occluded internal carotid arteries. In Group 2, CTA overestimated two stenoses; a correct diagnosis was made in 7 normal bifurcations, 3 mild, 2 moderate and 2 severe stenoses, 2 near occlusions, and 2 occlusions. Ulcerations were missed by CTA regardless of the technique utilized.     

Longitudinal changes in rheumatoid arthritis after rituximab administration assessed by quantitative and dynamic contrast-enhanced 3-T MR imaging: preliminary findings

We retrospectively assessed the longitudinal changes of rheumatoid arthritis under rituximab therapy by use of quantitative and dynamic contrast-enhanced 3-T magnetic resonance (MR) imaging of the metacarpophalangeal joints of 10 patients at baseline and 26 weeks (n = 10). Additional studies were available at 12 weeks (n = 9) and at 52 weeks (n = 5). Clinical activity was assessed by use of the 28-joint disease activity score (DAS28). MR imaging was used to assess volumes of synovial enhancement, osseous enhancement, and erosions and early rapid enhancement. DAS28 and serum C-reactive protein trended down over time and were significantly lower at 26 weeks. Volume of synovial enhancement and early rapid enhancement showed a significant minimum at 26 weeks and increased thereafter. The erythrocyte sedimentation rate paralleled these two trends. Osseous enhancement did not significantly change over time. Erosions showed a significant progression. Trends of DAS28 and erosions were significantly different (P = 0.0075). In conclusion, our preliminary results suggest that rituximab is associated with a decrease of the inflammatory activity of synovitis with a minimum at 26 weeks and increasing activity thereafter suggesting recurrence. Our results further suggest subclinical progression of erosions with an inverse relationship to decreasing disease activity scores. Further studies are needed to confirm these results.     

Intraindividual comparison of myocardial delayed enhancement MR imaging using gadobenate dimeglumine at 1.5 T and 3 T

For contrast-enhanced imaging techniques relying on strong T1 weighting, 3 T provides increased contrast compared with 1.5 T. The aim of our study was the intraindividual comparison of delayed enhancement MR imaging at 1.5 T and at 3 T. Twenty patients with myocardial infarction were examined at 1.5 T and 3 T. Fifteen minutes after injection of contrast agent (0.1 mmol gadobenate dimeglumine per kg body weight), inversion recovery gradient recalled echo (IR-GRE) sequences were acquired (1.5 T/3 T: TR 11.0/9.9 ms, TE 4.4/4.9 ms, flip 30°/30°, slice thickness 6/6 mm) to assess myocardial viability. Two observers rated image quality (Wilcoxon signed rank test). Quantification of hyperenhanced myocardium and standardized SNR/CNR measurements were performed (Student’s t test). There was no significant difference with respect to image quality (1.5 T/3 T: 3.5/3.3, p = 0.34, reader 1; 2.4/2.7, p = 0.12, reader 2) and infarction size (760 ± 566/828 ± 677 mm² at 1.5 T, 808 ± 639/826 ± 726 mm² at 3 T, reader 1/reader 2, p > 0.05). Mean SNR in hyperenhanced/normal myocardium was 19.2/6.2 at 1.5 T and 29.5/8.8 at 3 T (p < 0.05). Mean CNR was 14.3 at 1.5 T and 26.0 at 3 T (p < 0.05). Delayed enhancement MR imaging at 3 T is a robust procedure yielding superior tissue contrast at 3 T compared with 1.5 T which is, however, not reflected by increased image quality.