Diagnostic accuracy of second-generation dual-source computed tomography coronary angiography with iterative reconstructions: a real-world experience

Purpose

The authors evaluated the diagnostic accuracy of second-generation dual-source (DSCT) computed tomography coronary angiography (CTCA) with iterative reconstructions for detecting obstructive coronary artery disease (CAD).

Materials and methods

Between June 2010 and February 2011, we enrolled 160 patients (85 men; mean age 61.2±11.6 years) with suspected CAD. All patients underwent CTCA and conventional coronary angiography (CCA). For the CTCA scan (Definition Flash, Siemens), we use prospective tube current modulation and 70-100 ml of iodinated contrast material (Iomeprol 400 mgI/ ml, Bracco). Data sets were reconstructed with iterative reconstruction algorithm (IRIS, Siemens). CTCA and CCA reports were used to evaluate accuracy using the threshold for significant stenosis at ??50% and ??70%, respectively.

Results

No patient was excluded from the analysis. Heart rate was 64.3±11.9 bpm and radiation dose was 7.2±2.1 mSv. Disease prevalence was 30% (48/160). Sensitivity, specificity and positive and negative predictive values of CTCA in detecting significant stenosis were 90.1%, 93.3%, 53.2% and 99.1% (per segment), 97.5%, 91.2%, 61.4% and 99.6% (per vessel) and 100%, 83%, 71.6% and 100% (per patient), respectively. Positive and negative likelihood ratios at the per-patient level were 5.89 and 0.0, respectively.

Conclusions

CTCA with second-generation DSCT in the real clinical world shows a diagnostic performance comparable with previously reported validation studies. The excellent negative predictive value and likelihood ratio make CTCA a first-line noninvasive method for diagnosing obstructive CAD.     

Quantitative coronary arterial stenosis assessment by multidetector CT and invasive coronary angiography for identifying patients with myocardial perfusion abnormalities

Background

Semi-quantitative stenosis assessment by coronary CT angiography only modestly predicts stress-induced myocardial perfusion abnormalities. The performance of quantitative CT angiography (QCTA) for identifying patients with myocardial perfusion defects remains unclear.

Methods

CorE-64 is a multicenter, international study to assess the accuracy of 64-slice QCTA for detecting ??50% coronary arterial stenoses by quantitative coronary angiography (QCA). Patients referred for cardiac catheterization with suspected or known coronary artery disease were enrolled. Area under the receiver-operating-characteristic curve (AUC) was used to evaluate the diagnostic accuracy of the most severe coronary artery stenosis in a subset of 63 patients assessed by QCTA and QCA for detecting myocardial perfusion abnormalities on exercise or pharmacologic stress SPECT.

Results

Diagnostic accuracy of QCTA for identifying patients with myocardial perfusion abnormalities by SPECT revealed an AUC of 0.71, compared to 0.72 by QCA (P?=?.75). AUC did not improve after excluding studies with fixed myocardial perfusion abnormalities and total coronary arterial occlusions. Optimal stenosis threshold for QCTA was 43% yielding a sensitivity of 0.81 and specificity of 0.50, respectively, compared to 0.75 and 0.69 by QCA at a threshold of 59%. Sensitivity and specificity of QCTA to identify patients with both obstructive lesions and myocardial perfusion defects were 0.94 and 0.77, respectively.

Conclusions

Coronary artery stenosis assessment by QCTA or QCA only modestly predicts the presence and the absence of myocardial perfusion abnormalities by SPECT. Confounding variables affecting the relationship between coronary anatomy and myocardial perfusion likely account for some of the observed discrepancies between coronary angiography and SPECT results.     

Renal volume assessment with 3D ultrasound

Purpose

This study was undertaken to determine the accuracy of 3D ultrasound (US) in assessing renal volume, with multislice computed tomography (MSCT) considered as the gold standard.

Materials and methods

Forty-nine patients (30 men, 19 women; age range 30?C82 years) underwent abdominal contrast-enhanced MSCT and 3D-US performed with a 3.5-MHz 3D/4D convex-array probe. The results of the two modalities were compared with the Wilcoxon test. Variability between the two measurements was determined with the Bland-Altman method and reported in terms of bias and coefficient of repeatability (CoR).

Results

Mean values obtained were 210 ml with MSCT and 192 ml with 3D-US (p<0.001). Analysis of variability per patient between MSCT and 3D-US showed a bias of 19 ml, a CoR of 47 ml and an accuracy of 78%, with an average 3D-US underestimation of 19 ml (9%). Analysis of variability per kidney showed a bias of 9 ml, a CoR of 34 ml and an accuracy of 80%.

Conclusions

Three-dimensional US is a valuable technique for monitoring renal volume, whereas MSCT may be reserved for assessing renal anatomy and relationships with neighbouring organs.     

Multi slice computed tomography in the study of pulmonary metastases

Purpose

This study was undertaken to assess the performance of 16-slice computed tomography (MSCT) using Multi-Planar Reformatting (MPR), Maximum Intensity Projection (MIP) and Volume Rendering (VR) reconstructions to study pulmonary metastases.

Materials and methods

CT studies of 32 patients with pulmonary metastases were retrospectively reviewed. Images were assessed for the following parameters: number, size, location, distribution of the nodules and the presence of the “mass-vessel sign”. These parameters were evaluated by two observers on axial-source images and on MPR, MIP and VR reconstructions. Sensitivity of each reconstruction and interobserver agreement were calculated.

Results

Two-dimensional (2D) axial images and MIP and VR reconstructions exhibited 100% sensitivity for lesions >10 mm. For nodules 6–10 mm, sensitivity was 49%–55% for the 2D images, 90% for MIP and 80%–85% for VR reconstructions. For metastasis ≤5 mm, sensitivity was 22% for 2D images, 87%–89% for MIP and 55%–58% for VR reconstructions. Coronal and sagittal MPR, MIP and VR did not improve the detection rate compared with the corresponding axial images. MIP and VR provided overlapping results in detecting the “mass-vessel sign”.

Conclusions

MIP are the most sensitive reconstructions for detecting small pulmonary nodules.     

Anatomical variations in the origins of the celiac axis and the superior mesenteric artery: MDCT angiographic findings and their probable embryological mechanisms

Objectives

To identify the spectrum and prevalence of anatomical variations in the origin of the celiac axis (CA), the superior mesenteric artery (SMA) and their major branches by using multidetector computed tomographic (MDCT) angiography.

Methods

A retrospective evaluation was carried out on 1,500 abdominal MDCT angiography images. The aortic origins of the CA, the SMA and their major branch patterns were investigated.

Results

Normal aortic origins of CA and SMA were noted in 1,347 (89.8 %) patients. Seven types of CA and SMA origin variants were identified in 153 (10.2 %) patients. The three most common variations were hepatomesenteric trunk (67 patients, 4.47 %), celiomesenteric trunk (CMT) (51 patients, 3.4 %) and splenomesenteric trunk (18 patients, 1.2 %). An evaluation of CMT was classified as long (34 patients, 66.7 %) or short (17 patients, 33.3 %) subtypes, compared with the length of the common trunk. Further CMT classification was based on the origin of the left gastric artery: subtype I, 26 patients (53.1 %); subtype II, 5 patients (10.2 %); subtype III, 15 patients (30.6 %); subtype IV, 3 patients (6.1 %).

Conclusions

Dislocation interruption, incomplete interruption and persistence of the longitudinal anastomosis could be the embryological mechanisms of the variant origins of the CA, the SMA and their major branches.

Key Points

? Aortic origins of CA, SMA and their major branches were investigated. ? Celiomesenteric trunk includes several different subtypes and configurations. ? Probable embryological mechanisms of origin variants in these observed arteries were discussed. ? Origin variants in these observed arteries have wide-ranging health implications.     

ECG-Triggered Non-Contrast-Enhanced MR Angiography (TRANCE) versus Digital Subtraction Angiography (DSA) in patients with peripheral arterial occlusive disease of the lower extremities

Objective

To prospectively determine the diagnostic value of electrocardiography-triggered non-contrast-enhanced magnetic resonance angiography (TRANCE) of the lower extremities including the feet versus DSA.

Methods

All 43 patients with symptomatic peripheral arterial occlusive disease (PAOD) underwent TRANCE before DSA. Quality of MRA vessel depiction was rated by two independent radiologists on a 3-point scale. Arterial segments were graded for stenoses using a 4-point scale (grade 1: no stenosis; grade 2: moderate stenosis; grade 3: severe stenosis; grade 4: occlusion). Findings were compared with those of DSA.

Results

In the 731 vessel segments analysed, intra-arterial DSA revealed 283 stenoses: 33.6% moderate, 16.6% severe and 49.8% occlusions. TRANCE yielded a mean sensitivity, specificity, positive and negative predictive value and diagnostic accuracy to detect severe stenoses or occlusions of 95.6%, 97.4%, 87.2%, 99.2%, 97.1% for the thigh segments and 95.2%, 87.5%, 83.2%, 96.6%, 90.5% for the calf segments. Excellent overall image quality was observed for TRANCE in 91.4% versus 95.7% (DSA) for the thigh and in 60.7% versus 91.0% for the calves, while diagnostic quality of the pedal arteries was rated as insufficient.

Conclusion

TRANCE achieves high diagnostic accuracy in the thigh and calf regions, whereas the pedal arteries showed limited quality.     

Diagnostic accuracy of contrast-enhanced MR angiography and unenhanced proton MR imaging compared with CT pulmonary angiography in chronic thromboembolic pulmonary hypertension

Objective

To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) and the added benefit of unenhanced proton MR angiography compared with CT pulmonary angiography (CTPA) in patients with chronic thromboembolic disease (CTE).

Methods

A 2?year retrospective study of 53 patients with chronic thromboembolic pulmonary hypertension who underwent CTPA and MRI for suspected pulmonary hypertension and a control group of 36 patients with no CT evidence of pulmonary embolism. The MRI was evaluated for CTE and the combined diagnostic accuracy of ce-MRA and unenhanced proton MRA was determined. CE-MRA generated lung perfusion maps were also assessed.

Results

The overall sensitivity and specificity of CE-MRA in diagnosing proximal and distal CTE were 98% and 94%, respectively. The sensitivity improved from 50% to 88% for central vessel disease when CE-MRA images were analysed with unenhanced proton MRA. The CE-MRA identified more stenoses (29/18), post-stenosis dilatation (23/7) and occlusions (37/29) compared with CTPA. The CE-MRA perfusion images showed a sensitivity of 92% for diagnosing CTE.

Conclusion

CE-MRA has high sensitivity and specificity for diagnosing CTE. The sensitivity of CE-MRA for visualisation of adherent central and lobar thrombus significantly improves with the addition of unenhanced proton MRA which delineates the vessel wall.     

Role of 128 slice MSCT angiography in evaluation of congenital extra-cardiac intra-thoracic vascular anomalies in children

Purpose

To investigate the value and highlight the role of multi slice computed tomography (MSCT) angiography in evaluation of extra-cardiac intra thoracic vascular anomalies in children.

Coronary CT angiography: image quality, diagnostic accuracy, and potential for radiation dose reduction using a novel iterative image reconstruction technique��comparison with traditional filtered back projection

Objectives

To compare image noise, image quality and diagnostic accuracy of coronary CT angiography (cCTA) using a novel iterative reconstruction algorithm versus traditional filtered back projection (FBP) and to estimate the potential for radiation dose savings.

Methods

Sixty five consecutive patients (48 men; 59.3?±?7.7?years) prospectively underwent cCTA and coronary catheter angiography (CCA). Full radiation dose data, using all projections, were reconstructed with FBP. To simulate image acquisition at half the radiation dose, 50% of the projections were discarded from the raw data. The resulting half-dose data were reconstructed with sinogram-affirmed iterative reconstruction (SAFIRE). Full-dose FBP and half-dose iterative reconstructions were compared with regard to image noise and image quality, and their respective accuracy for stenosis detection was compared against CCA.

Results

Compared with full-dose FBP, half-dose iterative reconstructions showed significantly (p?=?0.001 ?C p?=?0.025) lower image noise and slightly higher image quality. Iterative reconstruction improved the accuracy of stenosis detection compared with FBP (per-patient: accuracy 96.9% vs. 93.8%, sensitivity 100% vs. 100%, specificity 94.6% vs. 89.2%, NPV 100% vs. 100%, PPV 93.3% vs. 87.5%).

Conclusions

Iterative reconstruction significantly reduces image noise without loss of diagnostic information and holds the potential for substantial radiation dose reduction from cCTA.     

Does Mechanical Thrombectomy in Acute Embolic Stroke Have Long-term Side Effects on Intracranial Vessels? An Angiographic Follow-up Study

Purpose

Mechanical thrombectomy (mTE) proved to be effective treating acute vessel occlusions with an acceptable rate of procedural complications. Potential long-term side effects of the vessel wall trauma caused by mechanical irritation of the endothelium are unknown up to now.

Methods

From a retrospectively established database of 640 acute stroke treatments, we selected 261 patients with 265 embolic vessel occlusions treated successfully by mTE without permanent implantation of a stent. Analysis comprised the type of devices used and the number of passes performed. Digital subtraction angiography immediately after treatment was evaluated for vasospasm, dissection, and extravasation. Control angiographic images were evaluated for any morphological change compared to the immediate posttreatment angiographic run.

Results

Recanalization was achieved with a median of one (range 1–10) mTE maneuvers. Vasospasm occurred in 69 territories (26.0 %) and was treated with glyceroltrinitrate in three. Dissection was observed in one vessel (0.4 %). Intraprocedural hemorrhage in two patients (0.8 %) was either wire or device induced. Follow-up digital subtraction angiography was available for 117 territories after a median of 107 days, revealing target vessel occlusion in one segment (0.9 %) and a de novo stenosis of four segments (3.4 %). All findings were clinically asymptomatic. Posttreatment vasospasm was more frequent in patients with de novo stenosis and occlusion (p = 0.038).

Conclusion

De novo stenoses and occlusions occur in a small proportion of patients after mTE. Because all lesions were clinically asymptomatic, this finding does not affect the overall benefit of the treatment. Vasospasm may predict late vessel wall changes.     

Difference of coronary stenosis severity between systolic and diastolic phases in quantitative CT angiography

Background

To compare the difference of coronary diameter stenosis by quantitative analysis of CT angiography (QCT) in the systolic (QCT-S) and diastolic phase (QCT-D) of the cardiac cycle, with invasive catheter angiography (QCA) as reference standard.

Comparison between 64-row CT angiography and digital subtraction angiography in the study of lower extremities: personal experience

Purpose

This study was undertaken to evaluate the potential of 64-row multislice computed tomography (CT) versus digital subtraction angiography (DSA) in detecting significant lesions of lower-extremity inflow and runoff arteries.

Materials and methods

Fifty-three patients underwent 64-row multislice CT and DSA over a mean of 36 days. The vascular tree was divided into 33 segments. Three readers independently reviewed the axial CT scans and multiplanar oblique and two- and three-dimensional reconstructions (maximum intensity projection and volume rendering) images to assess degree of stenosis according to four categories: 1 (0%–49% stenosis); 2 (50%–99% stenosis); 3 (occluded); 4 (not evaluable). In all cases, DSA was performed by arterial catheterisation.

Results

In 53 patients, 1,440 segments were evaluated (infrarenal aorta and 16 arterial segments for each leg; 42 bilateral studies, 11 unilateral studies). Compared with DSA, CT angiography yielded 97.2% sensitivity, 97% specificity, 92.5% positive predictive value, 98.9% negative predictive value, 97.1% diagnostic accuracy and 95.4% concordance on the degree of stenosis.

Conclusions

Sixty-four-row multislice CT proved to be helpful in detecting haemodynamically significant lesions in peripheral arterial occlusive disease and improved the results obtained with 4- and 16-slice multidetector CT. In addition, owing to the high spatial resolution and rigorous technique, no variations in the data obtained below the knee were detected, overcoming a limitation of earlier generations of CT scanners.     

Evaluation of monoenergetic late iodine enhancement dual-energy computed tomography for imaging of chronic myocardial infarction

Objectives

To evaluate image quality and diagnostic accuracy of selective monoenergetic reconstructions of late iodine enhancement (LIE) dual-energy computed tomography (DECT) for imaging of chronic myocardial infarction (CMI).

Methods

Twenty patients with a history of coronary bypass surgery underwent cardiac LIE-DECT and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI). LIE-DECT images were reconstructed as selective monoenergetic spectral images with photon energies of 40, 60, 80, and 100 keV and the standard linear blending setting (M_0.6). Images were assessed for late enhancement, transmural extent, signal characteristics and subjective image quality.

Results

Seventy-nine myocardial segments (23 %) showed LGE. LIE-DECT detected 76 lesions. Images obtained at 80 keV and M_0.6 showed a high signal-to-noise ratio (15.9; 15.1), contrast-to-noise ratio (4.2; 4.0) and sensitivity (94.9 %; 92.4 %) while specificity was identical (99.6 %). Differences between these series were not statistically significant. Transmural extent of LIE was overestimated in both series (80 keV: 40 %; M_0.6: 35 %) in comparison to MRI. However, observers preferred 80 keV in 13/20 cases (65 %, κ?=?0.634) over M_0.6 (4/20 cases) regarding subjective image quality.

Conclusions

Post-processing of LIE-DECT data with selective monoenergetic reconstructions at 80 keV significantly improves subjective image quality while objective image quality shows no significant difference compared to standard linear blending.

Key Points

? Late enhancement dual-energy CT allows for detection of chronic myocardial infarction. ? Monoenergetic reconstructions at 80 keV significantly improve subjective image quality. ? 80 keV and standard linear blending reconstructions show no significant differences. ? Extent of CMI detected with LIE-DECT is overestimated compared with MRI.     

Application of multislice detector spiral computed tomography to intracranial aneurysms: first clinical experience

Purpose. To identify advantages when using the new multislice spiral CT technology (MSCT) for the detection and demonstration of intracranial aneurysms with CT angiography (CTA)? Material and methods. Patients with suspected intracranial aneurysms underwent 4- and 8-slice spiral CTA. Image postprocessing included “maximum intensity projection” (MIP),“volume rendering” (VR) and additionally curved multiplanar reconstructions (MPR) for aneurysms suspected at the carotid siphon.The results were compared with those achieved with digital subtraction angiography (DSA). Results. In 19 patients 21 out of 22 aneurysms were detected by CTA. A high resolution three-dimensional view of the aneurysm morphology in spatial relation to the surrounding structures was achieved.Further information could be gained by making a detailed examination of the inside wall of the aneurysm, using virtual vascular 3D-endoscopy and virtual 3D-craniotomy. Conclusion. Compared to DSA,MS-CTA is a useful additional and in selected cases alternative modality for the detection with marked advantages in the demonstration of intracranial aneurysms.     

Correlation of regional distribution and morphological pattern of calcification at CT coronary artery calcium scoring with non-calcified plaque formation and stenosis

Objective

To investigate whether regional calcification patterns at CT coronary artery calcium scoring (CCS) correlate with stenosis and non-calcified plaque formation.

Methods

We studied 106 patients with quantitative catheter angiography (QCA), CCS, and coronary CT angiography (cCTA). CCS was determined globally and for each artery separately. The morphological pattern of each calcification was classified as calcified nodule, shell-like, or diffuse. cCTA studies were evaluated for non-calcified plaque. The global and regional CCS and the calcification pattern were correlated with stenosis ≥50% and non-calcified plaque.

Results

A total of 48/106 patients had stenosis ≥50% on QCA. There was weak correlation (r?=?0.36) of the global CCS with stenosis. Correlation was stronger per vessel (r?=?0.55–r?=?0.67). Shell-like and diffuse calcifications were significantly (p?=?0.0001) more frequently associated with ≥50% stenosis and non-calcified plaque (p?=?0.04) than calcified nodules.

Conclusion

As shown before, the global CCS does not correlate well with stenosis. However, regional calcium distribution and specific patterns of calcification are correlated with stenosis and non-calcified plaque. Thus, the specificity of CT calcium scoring for identifying individuals with obstructive disease could be improved by vessel-based rather than global quantification of calcium and by differentiating specific morphological patterns of calcification.     

Automated quantitative Rb-82 3D PET/CT myocardial perfusion imaging: Normal limits and correlation with invasive coronary angiography

Background

We aimed to characterize normal limits and to determine the diagnostic accuracy for an automated quantification of 3D 82-Rubidium (Rb-82) PET/CT myocardial perfusion imaging (MPI).

Methods

We studied 125 consecutive patients undergoing Rb-82 PET/CT MPI, including patients with suspected coronary artery disease (CAD) and invasive coronary angiography, and 42 patients with a low likelihood (LLk) of CAD. Normal limits for perfusion and function were derived from LLk patients. QPET software was used to quantify perfusion abnormality at rest and stress expressed as total perfusion deficit (TPD).

Results

Relative perfusion databases did not differ in any of the 17 segments between males and females. The areas under the receiver operating characteristic curve for detection of CAD were 0.86 for identification of ??50% and ??70% stenosis. The sensitivity/specificity was 86%/86% for detecting ??50% stenosis and 93%/77% for ??70% stenosis, respectively. In regard to normal limits, mean rest and stress left ventricular ejection fraction (LVEF) were 67%?±?10% and 75%?±?9%, respectively. Mean transient ischemic dilation ratio was 1.06?±?0.14 and mean increase in LVEF with stress was 7.4%?±?6.1% (95th percentile of 0%).

Conclusion

Normal limits have been established for 3D Rb-82 PET/CT analysis with QPET software. Fully automated quantification of myocardial perfusion PET data shows high diagnostic accuracy for detecting obstructive CAD.     

Multidetector CT and CT angiography in mesenteric ischemia

Purpose

To evaluate the role of 64-multidetector CT in assessment of mesenteric vascular ischemia in clinically suspected patients.

Patients and methods

This study included 38 patients during period from October 2009 to October 2011. The patients age ranged from 38 to 72 year old (mean age was 57 ± 11.2 years). All cases met the criteria of acute non traumatic (28 patients) or chronic abdominal pain (10 patients) and suspected mesenteric vascular ischemia. All 38 cases were evaluated in surgery department, then underwent CT of the abdomen and pelvis & CTA by using 64 multislice GE light speed VCT. MDCT& CT angiographic findings were correlated with surgical findings in acute mesenteric ischemia (AMI) cases & conventional angiography in chronic mesenteric ischemia (CMI) cases.

Results

MDCT findings alone were nonspecific for detection of MI. The sensitivity, specificity& accuracy of CTA in diagnosis of AMI after surgical confirmation were 96%, 66.6% & 92.8% respectively, while in CMI the sensitivity, specificity & accuracy were 88.8%, 100%, 90% respectively, after confirmation by conventional angiography.

Conclusion

CTA scan appears to be an excellent tool to find out and localize cases of AMI rather than in CMI cases.     

Preoperative vascular mapping with multislice CT of deep inferior epigastric artery perforators in planning breast reconstruction after mastectomy

Purpose

Our aim was to evaluate the usefulness of computed tomography angiography (CTA) in vascular mapping for planning breast reconstruction after mastectomy using a free flap made with the deep inferior epigastric perforators (DIEP).

Materials and methods

We retrospectively evaluated 41 patients, mean age 57 years, scheduled for mastectomy. CTA was performed with a 64-row scanner (Aquilion 64, Toshiba Medical Systems, Japan), with injection of 100 ml of contrast medium (iomeprol 350 mgI/ml, Bracco, Italy) at 4.5 ml/s. Maximum intensity projection (MIP) and threedimensional volume-rendering (VR) reconstructions were made to mark perforator positions. Presentation frequency, anatomy and artery opacification quality were evaluated.

Results

DIEP were always depicted (n=81) and subdivided according to Taylor’s classification into type I (65%), type II (28%), and type III (7%). We observed a mean of three (range, 1–5) DIEP arteries on the right and two (range, 1–5) on the left side. The superficial inferior epigastric artery (SIEA) was depicted in 6/41 patients, bilaterally in three cases. Opacification was optimal in 30/41 cases, venous contamination due to late arterial phase in eight and low opacification due to early scan in three.

Conclusions

Studying DIEP with CTA is useful in the surgical planning of breast reconstruction, even though it requires careful optimisation owing to the critical timing of opacification typical of that vascular district.     

Effective dose to patient measurements in flat-detector and multislice computed tomography: a comparison of applications in neuroradiology

Purpose

Flat-detector CT (FD-CT) is used for a variety of applications. Additionally, 3D rotational angiography (3D DSA) is used to supplement digital subtraction angiography (DSA) studies. The aim was to measure and compare the dose of (1) standard DSA and 3D DSA and (2) analogous FD-CT and multislice CT (MSCT) protocols.

Methods

Using an anthropomorphic phantom, the effective dose to patients (according to ICRP 103) was measured on an MSCT and a flat-detector angiographic system using standard protocols as recommended by the manufacturer.

Results

(1) Evaluation of DSA and 3D DSA angiography protocols: ap.-lat. Standard/low-dose series 1/0.8 mSv, enlarged oblique projection 0.3 mSv, 3D DSA 0.9 mSv (limited coverage length 0.3 mSv). (2) Comparison of FD-CT and MSCT: brain parenchyma imaging 2.9 /1.4 mSv, perfusion imaging 2.3/4.2 mSv, temporal bone 0.2 /0.2 mSv, angiography 2.9/3.3 mSv, limited to the head using collimation 0.5/0.5 mSv.

Conclusion

The effective dose for an FD-CT application depends on the application used. Using collimation for FD-CT applications, the dose may be reduced considerably. Due to the low dose of 3D DSA, we recommend using this technique to reduce the number of DSA series needed to identify working projections.

Key Points

? Effective dose of FD-CT in comparison to MSCT is in comparable range. ? Collimation decreases the dose of FD-CT effectively. ? Effective dose of 3-D angiography is identical to 2-D DSA. ? Different FD-CT programs have different dose.     

Role of 64-slice cardiac computed tomography in the evaluation of patients with non-ST-elevation acute coronary syndrome

Purpose

This study was done to evaluate the feasibility, sensitivity and specificity of 64-slice computed tomography (CT) in identifying haemodynamically significant (>50%) coronary artery stenoses in patients with suspected acute coronary syndrome (ACS) by correlating the CT findings with the clinical event and data provided by conventional coronary angiography (CCA).

Materials and methods

Sixty-four patients (38 men and 26 women; mean age 65 years; range±10 years) presenting to our hospital’s emergency department with a clinical suspicion of ACS were studied with 64-slice CT followed by CCA within 24 h of arrival.

Results

Two patients (3.1%) were excluded from the analysis due to artefacts. Per-patient analysis in the remaining 62 patients identified 24 cases (38.7%) of negative CT findings (no stenoses or stenoses <50%), 35 cases of positive CT findings (56.4%) with identification of the culprit lesion, two cases in which the culprit lesion was not identified and one patient with unconfirmed stenosis. Sensitivity and specificity were 94.6% and 96%, respectively. Per-vessel analysis (186 vessels) revealed 17 non-evaluable vessels (9.1%) due to motion artefacts, 61 vessels (32.8%) with stenosis >50%, seven overestimated vessels (3.7%) due to extensive calcifications, three vessels (1.6%) with underestimated stenosis and 98 vessels (52.6%) without stenosis. Sensitivity and specificity were 95.3% and 93.3%, respectively.

Conclusions

In this type of emergency, coronary CT angiography could lead to considerably lower healthcare costs by identifying patients without coronary disease and allowing immediate discharge without any need for further diagnostic procedures.