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To assess the effect of a noise-optimized image-based virtual monoenergetic imaging (VMI+) algorithm in direct comparison with the traditional VMI technique and standard linearly-blended images emulating 120-kVp acquisition (M_0.3) on image quality at dual-energy CT in patients with lung cancer.Dual-source dual-energy CT examinations of 48 patients with biopsy-proven primary (n=31) or recurrent (n=20) lung cancer were evaluated. Images were reconstructed as M_0.3, and VMI+ and traditional VMI series at 40, 55, and 70keV. Attenuation of tumor, descending aorta, pulmonary trunk, latissimus muscle, and noise were measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Five-point scales were used by three observers to subjectively evaluate general image impression, tumor delineation, image sharpness, and image noise.Background noise was consistently lower with VMI+ compared to VMI at all keV levels (all p0.0001) and M_0.3 (all p≤0.0004). Tumor SNR and CNR peaked in the 40keV VMI+ series, significantly higher compared to all VMI and M_0.3 series (all p0.0008). Observers preferred the 55keV VMI+ series regarding general image impression and tumor delineation compared to all other series (all p0.0001). Image sharpness and image noise ratings were highest in the 55keV VMI+ and 70keV VMI and VMI+ reconstructions.Tumor CNR peaked at 40keV VMI+ while observers preferred 55keV VMI+ series overall other series for dual-energy CT of lung cancer. The noise-optimized VMI+ technique showed significantly lower background noise and higher SNR and CNR compared to the traditional VMI technique at matching keV levels.

Rationale and Objectives This investigation aimed to evaluate the impact on treatment regimen and clinical outcome of dual-energy computed tomography (DECT) in patients with suspected gouty arthritis. Materials and Methods We retrospectively analyzed electronic medical records (EMR) of 39 patients (36 male, 3 female; age range, 36–85 years) who underwent DECT of peripheral joints because of suspected gouty arthritis. We assessed the prior medical history, lab results, treatment regimen, and medications before and after DECT, and changes in subjective severity of symptoms as stated by patients in the EMR. The presence of monosodium urate (MSU) crystals in the index joint was verified with DECT. Results Several patients had a prior diagnosis of gout (n = 9), hyperuricemia (n = 6), rheumatoid arthritis (n = 3), or psoriatic arthritis (n = 3). Elevated uric acid blood levels were detected in 32 patients (82%) before DECT. On DECT, MSU crystals were detected in 23 patients (59%). Of the 36 cases, the current treatment regimen was modified after DECT to gout-specific therapy in 22 cases and other rheumatic diseases were targeted in 14 cases. Several medications were prescribed more frequently based after DECT compared to before DECT imaging, including steroids (n = 20 vs. n = 12, respectively), colchicine (n = 13 vs. n = 4, respectively), and urate-lowering medication (n = 18 vs. n = 11, respectively). A subjective reduction of clinical symptoms during cumulative follow-up was reported by 34 patients (87.2%). Conclusions Both positive and negative findings of MSU crystals on DECT have a significant impact on the treatment regimen and clinical outcome of patients with suspected gouty arthritis and facilitate differentiation from other rheumatic diseases.

To evaluate a novel monoenergetic reconstruction algorithm (nMERA) with improved noise reduction for dual-energy CT (DECT) of pancreatic adenocarcinoma.Sixty patients with suspected pancreatic carcinoma underwent dual-source dual-energy CT with arterial phase. Images were reconstructed as linearly-blended 120-kV series (M_0.6) and with the standard monoenergetic (sMERA) and the novel monoenergetic algorithm (nMERA) with photon energies of 40, 55, 70 and 80 keV. Objective image quality was compared regarding image noise, pancreas attenuation, signal-to-noise ratio (SNR) and pancreas-to-lesion contrast. Subjective image quality was assessed by two observers.Thirty pancreatic adenocarcinomas were detected. nMERA showed significantly reduced image noise at low keV levels compared with sMERA images (55 keV: 7.19 ± 2.75 vs. 20.68 ± 7.01 HU; 40 keV: 7.33 ± 3.20 vs. 37.22 ± 14.66 HU) and M_0.6 (10.69 ± 3.57 HU). nMERA pancreatic SNR was significantly superior to standard monoenergetic at 40 (47.02 ± 23.41 vs. 9.37 ± 5.83) and 55 keV (28.29 ± 16.86 vs. 9.88 ± 7.01), and M_0.6 series (11.42 ± 6.00). Pancreas-to-lesion contrast peaked in the nMERA 40 keV series (26.39 ± 16.83) and was significantly higher than in all other series (p0.001). nMERA 55 keV images series were consistently preferred by both observers over all other series (p0.01).nMERA DECT can significantly improve image quality and pancreas-to-lesion contrast in the diagnosis of pancreatic adenocarcinoma.

To investigate the association between aortic root calcification (ARC) and coronary artery calcification (CAC) assessed by coronary artery calcium-scoring dual-source computed tomography (DSCT).We retrospectively analyzed 143 consecutive patients who underwent coronary artery calcium-scoring during coronary DSCT angiography. 57 patients had findings of ARC on calcium-scoring scans. ARC volume (ARCV) and Agatston coronary artery calcium score (CACS) were calculated. Chi-square test was used to assess differences of categorical variables between patients with and without ARC. Statistical significances between both groups were assessed with the independent-Sample t test.Compared with patients without ARC (n=86), patients with ARC (n=57) showed a significantly higher presence of CAC (87.7% vs. 24.4%; P0.001), and a higher mean CACS (700.6 ± 941.2 vs. 256.4 ± 724.3; P=0.009) in patients with CAC. Patients with a calculated ARCV40 mm(3) (n=32) showed significantly higher rates of severe CAC (56.3% vs. 24.0%; P=0.014) compared with patients with an ARCV40 mm(3) (n=25). Compared with patients without CAC (n=42), patients with CAC (n=101) showed a significantly higher presence of ARC (83.3% vs. 50.5%; P0.001) and a higher mean ARCV (95.4 ± 116.2mm(3) vs. 29.7 ± 33.0 mm(3); P=0.003). Severe CAC (n=24) correlated with an increased mean ARCV (122.3 ± 148.8mm(3)) compared to patients with minimal to moderate CAC (n=33, mean ARCV: 61.9 ± 64.8mm(3); P0.05).The extent of ARC is directly associated with the presence and degree of CAC on calcium-scoring scans during coronary DSCT angiography.

To compare radiation exposure and image quality of second-generation 128-slice dual-source CT (DSCT) coronary angiography (cCTA) protocols.We retrospectively analyzed data from four groups with 25 patients, each examined by one of the following DSCT cCTA protocols: prospectively ECG-gated high-pitch (group 1) or sequential (group 2) acquisition, retrospectively ECG-gated acquisition in dual-energy (DECT, group 3) or dual-source (group 4) mode. CT dose index volume, dose length product, estimated radiation dose, contrast-to-noise- and signal-to-noise-ratios were compared. Subjective image quality was rated by two observers blinded to the protocols.High-pitch DSCT showed a mean estimated radiation dose of 1.27 ± 0.62 mSv, significantly (p 0.01) lower than sequential (2.04 ± 0.94 mSv), dual-energy (3.97 ± 1.29 mSv) or dual-source (8.11 ± 4.95 mSv) acquisition. Image noise showed no statistical difference (p 0.91), ranging from 15.2 ± 4.4 (group 2) up to 24.5 ± 22.0 (group 4). Each protocol showed diagnostic image quality in at least 98.1 % of evaluated coronary segments without significant differences (p 0.05).Prospectively ECG-gated DSCT protocols enable cCTA with significant dose reduction and consistently diagnostic image quality. In patients requiring retrospectively ECG-gated DSCT for functional analysis or due to arrhythmia, dual-energy mode should be preferred over dual-source mode as it significantly decreases estimated dose without compromising image quality.

To investigate low-tube-voltage 80-kVp computed tomography (CT) of head and neck primary and recurrent squamous cell carcinoma (SCC) regarding objective and subjective image quality.We retrospectively evaluated 65 patients (47 male, 18 female; mean age: 62.1 years) who underwent head and neck dual-energy CT (DECT) due to biopsy-proven primary (n = 50) or recurrent (n = 15) SCC. Eighty peak kilovoltage and standard blended 120-kVp images were compared. Attenuation and noise of malignancy and various soft tissue structures were measured. Tumor signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was rated by three reviewers using 5-point grading scales regarding overall image quality, lesion delineation, image sharpness, and image noise. Radiation dose was assessed as CT dose index volume (CTDIvol). Interobserver agreement was calculated using intraclass correlation coefficient (ICC).Mean tumor attenuation (153.8 Hounsfield unit (HU) vs. 97.1 HU), SNR (10.7 vs. 8.3), CNR (8.1 vs. 4.8), and subjective tumor delineation (score, 4.46 vs. 4.13) were significantly increased (all P 0.001) with 80-kVp acquisition compared to standard blended 120-kVp images. Noise of all measured structures was increased in 80-kVp acquisition (P 0.001). Overall interobserver agreement was good (ICC, 0.86; 95 % confidence intervals: 0.82-0.89). CTDIvol was reduced by 48.7 % with 80-kVp acquisition compared to standard DECT (4.85 ± 0.51 vs. 9.94 ± 0.81 mGy cm, P 0.001).Head and neck CT with low-tube-voltage 80-kVp acquisition provides increased tumor delineation, SNR, and CNR for CT imaging of primary and recurrent SCC compared to standard 120-kVp acquisition with an accompanying significant reduction of radiation exposure.

To evaluate quantitative dual-energy computed tomography (DECT) for phantomless analysis of cancellous bone mineral density (BMD) of vertebral pedicles and to assess the correlation with pedicle screw pull-out strength.Twenty-nine thoracic and lumbar vertebrae from cadaver specimens were examined with DECT. Using dedicated post-processing software, a pedicle screw vector was mapped (R1, intrapedicular segment of the pedicle vector; R2, intermediate segment; R3, intracorporal segment; global, all segments) and BMD was calculated. To invasively evaluate pedicle stability, pedicle screws were drilled through both pedicles and left pedicle screw pull-out strength was measured. Resulting values were correlated using the paired t test and Pearson's linear correlation.Average pedicle screw vector BMD (R1, 0.232 g/cm(3); R2, 0.166 g/cm(3); R3, 0.173 g/cm(3); global, 0.236 g/cm(3)) showed significant differences between R1-R2 (P 0.002) and R1-R3 (P 0.034) segments while comparison of R2-R3 did not reach significance (P 0.668). Average screw pull-out strength (639.2 N) showed a far stronger correlation with R1 (r = 0.80; P 0.0001) than global BMD (r = 0.42; P = 0.025), R2 (r = 0.37; P = 0.048) and R3 (r = -0.33; P = 0.078) segments.Quantitative DECT allows for phantomless BMD assessment of the vertebral pedicle. BMD of the intrapedicular segment shows a significantly stronger correlation with pedicle screw pull-out strength than other segments.• Quantitative dual-energy CT enables evaluation of pedicle bone mineral density. • Intrapedicular segments show significant differences regarding bone mineral density. • Pedicle screw pull-out strength correlated strongest with R1 values. • Dual-energy CT may improve preoperative assessment before transpedicular screw fixation.

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). 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. 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. 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. • 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.

We investigated a novel sequence with radial k-space sampling, gridding and sliding window reconstruction with bSSFP contrast that allows for true real-time functional cardiac evaluation independent from respiration and ECG triggering. 12 healthy volunteers underwent 1.5 T cardiac MRI. Single-shot short axis views were acquired with a) standard retrospectively ECG-gated segmented breath-hold (bh) bSSFP and with the real-time radial bSSFP sequence with a nominal temporal resolution of b) 16 fps (frames per second) and c) 40 fps. Radial bSSFP were acquired during free breathing without ECG synchronization. Left ventricular functional parameters (EDV, ESV, SV and EF) were compared and quality of wall motion depiction was assessed. Contrast-to-noise-ratio (CNR) of myocardium/blood pool in the left ventricle was calculated. EF showed excellent correlation (Bland-Altman r = 0.99; Lin rho = 0.91) between bh-bSSFP (65 %) and 40 fps radial (64 %) and moderate correlation (r = 0.84, rho = 0.20) with 16 fps radial bSSFP (56 %). While EDV was in good agreement for all three sequences, ESV was significantly overestimated with 16 fps radial bSSFP. Despite lower CNR, image quality for wall motion assessment was rated significantly better for 40 fps compared to 16 fps radial bSSFP due to the faster temporal resolution. Left ventricular functional analysis with fast true real-time radial bSSFP is in good agreement with standard ECG-gated bh-bSSFP. The independency from ECG synchronization and breathing promises a robust method for patients with impaired cardiopulmonary status in whom breath-hold and good quality ECG cannot be achieved.

Purpose To compare test bolus and bolus tracking for the determination of scan delay of high-pitch dual-source CT pulmonary angiography in patients with suspected pulmonary embolism using 50 ml of contrast material. Materials and methods Data of 80 consecutive patients referred for CT pulmonary angiography were evaluated. All scans were performed on a 128-channel dual-source CT scanner with a high-pitch protocol (pitch 3.0, 100 kV, 180 mA s). Contrast enhancement was achieved by injecting 50 ml of iomeprol followed by a saline chaser of 50 ml injected at a rate of 4 ml/s. The scan delay was determined using either the test bolus ( n = 40) or bolus tracking ( n = 40) technique. Test bolus required another 15 ml CM to determine time to peak enhancement of the contrast bolus within the pulmonary trunk. Attenuation profiles in the pulmonary trunk and on segmental level as well as in the ascending aorta were measured to evaluate the timing techniques. Additionally, overall image quality was evaluated. Results In all patients an adequate and homogeneous contrast enhancement of more than 250 HU was achieved in the pulmonary arteries. No statistically significant difference between test bolus and bolus tracking was found regarding attenuation of the pulmonary arteries or overall image quality. However, using bolus tracking 15 ml CM less was injected. Conclusion A homogeneous opacification of the pulmonary arteries and sufficient image quality can be achieved with both the bolus tracking and test bolus techniques with significant lower contrast doses compared to conventional contrast material injection protocols.

Purpose On lung perfusion analysis with dual energy CT (DECT) in patients with suspected pulmonary embolism (PE) commonly three patterns of perfusion defects (PD) are observed: wedge-shaped, circumscribed but not wedge-shaped, and patchy. We investigated the influence of different window settings on the identification of the underlying pathologies for these types of PD. Materials and methods 3724 segments in 196 consecutive patients who underwent pulmonary DECT angiography for clinically suspected acute PE were analyzed. Iodine distribution in the lung parenchyma was calculated from the dual energy data and displayed as color map in axial, sagittal and coronal view. Afterwards, lung and angiography window were applied separately and assessed for pulmonary embolism and pathologies of the lung parenchyma. Results 1420 segments in 141 patients showed PD, of which 276 were wedge-shaped, 287 circumscribed and 857 patchy. Circumscribed PD were associated in 99% with interstitial or alveolar fluid collections and in 1% with located bullae. Patchy PD were associated in 65% with emphysematous or fibrotic changes, in 38% with diffuse infiltrations or interstitial fluid collections and in 0.2% with PE. The underlying pathologies for wedge-shaped PD were in 78% PE, in 3% tumors compressing pulmonary arteries, in another 3% located bullae and in further 3% infiltrations. 13% ( n =15) of the segments in this group did not show vascular or parenchymal pathologies, but in 80% ( n =10) of these cases patients had PE in another segment. Totally n =6 of wedge-shaped PD in 5 patients remained with unclear direct cause. Conclusion Whereas patchy and circumscribed PD are almost exclusively associated with pathologies of the lung parenchyma, wedge-shaped PD are mostly associated with PE. For a small number of wedge-shaped PD the underlying cause cannot be detected with DECT. Very small peripherally situated micro-emboli may be discussed as a reason. However, prospective trials are needed to clarify the value of this finding.

The purpose of this article is to determine the degree to which the skin entrance dose could be lowered, by adjusting exposure parameters and filtration, and the subsequent effect on readers' confidence levels of digital radiographs.The study was prospectively performed on a cadaver. Digital radiographs of bones were evaluated and scored on a 9-point scale separately by four radiologists who were blinded to the types of filtration and doses used. The study entailed three phases: phase 1, random dose and filter; phase 2, fixed filter and varying radiation doses (100%, 75%, 50%, and 25% of the standard recommended dose); and phase 3, fixed dose and varying filtration (no filtration, aluminum filter, and aluminum-copper filter). Skin entrance dose was measured using a dosimeter placed on the skin. Differences in scores were tested using a Friedman test.The mean scores given to images with 100%, 75%, 50%, and 25% of the recommended standard dose were 6.18, 6.1, 5.11, and 4.07, respectively. No significant difference was noted between 100%- and 75%-dose images (p = 0.1). A significant difference (p0.0001) was noted when we compared the 100%- and 75%-dose images with the 50%- and 25%-dose images. The mean scores given for no filtration, aluminum filtration, and aluminum-copper filtration were 5.67, 5.43, and 5.18, respectively. No significant difference between no filtration and aluminum filtration (p = 0.411) was noted. A significant difference was detected between no filtration and aluminum-copper filtration (p = 0.012). The combination of an aluminum filter and a 75% standard dose achieved a 31.1% reduction in skin entrance dose.It is possible to achieve a 31.1% reduction in skin entrance dose for imaging bony structures by using 75% of the standard dose and aluminum filtration without significantly affecting image quality.

Lung perfusion analysis at dual energy CT (DECT) is sensitive to beam hardening artifacts from dense contrast material (CM). We compared two scan and four CM injection protocols in terms of severity of artifacts and attenuation levels in the thoracic vessels.Data of 120 patients who had undergone dual source dual energy CT pulmonary angiography for suspected acute pulmonary embolism were evaluated. Group 1 (n=30) was scanned in craniocaudal direction using 64×0.6 mm collimation; groups 2-4 (n=30 each) were scanned in caudocranial direction using 14×1.2 mm collimation. In groups 1-3 biphasic injection protocols with different amounts of CM and NaCl were investigated. In group 4 a split-bolus protocol with an initial CM bolus of 50 ml followed by 30 ml of a 70%:30% NaCl/CM mixture and a 50 ml NaCl chaser bolus was used. CT density values in the subclavian vein (SV), superior vena cava (SVC), pulmonary artery tree (PA), and the descending aorta (DA) were measured. Artifacts arising from the SV and SVC on DE pulmonary iodine distribution map were rated on a scale from 1 to 5 (1=fully diagnostic; 5=non-diagnostic) by two blinded readers.In protocol 4 mean attenuation in the SV (645±158 HU) and SVC (389±114 HU) were significantly lower compared to groups 1-3 (p0.002). Artifacts in group 4 (1.1±0.4 and 1.5±0.7 for the SV and SVC, respectively) were rated significantly less severe compared to group 1 (3.2±1.0 and 3.0±1.1), 2 (2.6±1.1 and 2.3±1.0) and 3 (1.9±0.9 and 1.9±0.7) (p0.01 for all), whereas no significant difference was found between groups 1 and 2 for the subclavian vein (p=0.07). Attenuation in the PA was also significantly lower in group 4 (282±116 HU) compared to group 1 (397±137 HU), group 2 (376±115 HU) and group 3 (311±104 HU), but still on a diagnostic level.Split-bolus injection provides sufficient attenuation for pulmonary DECT angiography while beam hardening artifacts arising from high density contrast material in the thoracic vessels can be reduced significantly.

Backround Detection of myocardial infarction has been the focus of considerable research over the past few decades. Recently developed dual source computed tomography (DSCT) scanners with dual energy mode have been used to detect myocardial infarction, but the studies on this topic are few. Purpose To evaluate the feasibility and performance of dual energy CT (DECT) during arterial phase in coronary CT angiography for the detection of chronic infarction compared with late enhancement MRI (LE-MRI) and histopathology in a porcine model of reperfused myocardial infarction. Material and Methods Myocardial infarctions were induced by 30 min occlusion of the proximal left anterior descending coronary artery in eight minipigs. DECT, post-contrast LE-MRI and histopathology were performed 60 days after infarct induction. The CT scan was performed in dual energy mode using a dedicated protocol. Myocardial iodine distribution was superimposed as color maps on grey scale multiplanar reformats of the heart. Two radiologists in consensus interpreted all imaging studies for presence of gadolinium uptake at LE-MRI reduced iodine content at DECT and hypoenhanced areas in the initial 100 kV coronary CT angiography images that were acquired during the DECT-acquisition. Results were compared with histopathology. Results Based on evaluable segments, DECT showed a sensitivity and specificity of 0.72 and 0.88; LE-MRI showed a sensitivity and specificity of 0.78 and 0.92; and the 100 kV data-set of the DECT scan showed a sensitivity and specificity of 0.60 and 0.93, respectively, for the detection of histological proved ischemia. Conclusion DECT during arterial phase coronary CT angiography, which is ordinarily used for coronary artery evaluation, is feasible for the detection of a chronic reperfused myocardial infarction.

To prospectively compare traditional filtered back projection (FBP) and iterative image reconstruction for the evaluation of heavily calcified arteries with coronary computed tomography (CT) angiography.The study had institutional review board approval and was HIPAA compliant. Written informed consent was obtained from all patients. Fifty-five consecutive patients (35 men, 20 women; mean age, 58 years ± 12 [standard deviation]) with Agatston scores of at least 400 underwent coronary CT angiography and cardiac catheterization. Image data were reconstructed with both FBP and iterative reconstruction techniques with corresponding cardiac algorithms. Image noise and subjective image quality were compared. To objectively assess the effect of FBP and iterative reconstruction on blooming artifacts, volumes of circumscribed calcifications were measured with dedicated volume analysis software. FBP and iterative reconstruction series were independently evaluated for coronary artery stenosis greater than 50%, and their diagnostic accuracy was compared, with cardiac catheterization as the reference standard. Statistical analyses included paired t tests, Kruskal-Wallis analysis of variance, and a modified McNemar test.Image noise measured significantly lower (P = .011-.035) with iterative reconstruction instead of FBP. Image quality was rated significantly higher (P = .031 and .042) with iterative reconstruction series than with FBP. Calcification volumes measured significantly lower (P = .019 and .026) with iterative reconstruction (44.3 mm(3) ± 64.7 and 46.2 mm(3) ± 68.8) than with FBP (54.5 mm(3) ± 69.5 and 56.3 mm(3) ± 72.5). Iterative reconstruction significantly improved some measures of per-segment diagnostic accuracy of coronary CT angiography for the detection of significant stenosis compared with FBP (accuracy: 95.9% vs 91.8%, P = .0001; specificity: 95.8% vs 91.2%, P = .0001; positive predictive value: 76.9% vs 61.1%, P = .0001).Iterative reconstruction reduces image noise and blooming artifacts from calcifications, leading to improved diagnostic accuracy of coronary CT angiography in patients with heavily calcified coronary arteries.

Rationale and Objectives We sought to assess retrospectively the added value of coronal reformations from isotropic voxels obtained with 64-slice multidetector row computed tomography (CT) of the acute abdomen. Materials and Methods This retrospective study was approved by the institutional review board and informed consent was waived. Multidetector helical 64-section CT (section thickness, 0.6 mm; pitch 1.75; table speed 35 mm/sec) was performed in 100 patients (60 women and 40 men; age range, 9∓85 years; mean age, 45.2 years) with acute nontraumatic abdominal pain who had been referred from the emergency department. Axial images were reconstructed with 5-mm-thick sections at 5-mm intervals. The second data set was reformatted coronally, with 3-mm-thick sections at 3-mm intervals. Four independent, blinded readers with various level of training interpreted first the axial scans alone and then followed immediately by the coronal scans. Confidence in the visualization of anatomy and pathology was scored on a 5-point scale. The final diagnosis was determined by surgical and pathologic reports and by clinical follow-up in those who did not undergo surgery. Results Based upon the individual patient’s clinical history and other comorbid factors, 92 patients received intravenous contrast and 90 patients received oral contrast. In 45 patients, no CT abnormalities were detected for an explanation of the abdominal pain. Mean sensitivity and specificity of axial CT alone were 92.5% and 91%, respectively. No significant differences in sensitivity and specificity were observed for the use of combined axial and coronal images. For the most inexperienced reader, the coronal reformations were helpful in 95% of cases, while for the most experienced reader, the coronal reformations were helpful in 35% of the cases. The coronal images were deemed helpful in an average of 62.3% of the cases for the four readers. However, diagnosing subtle pathology in the abdominal wall was difficult on coronal reformations alone. Overall, coronal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal abdominal structures and in the diagnosis of abdominal pathology. Conclusion Axial and coronal reformations of 64-section multidetector row CT have equal sensitivity and specificity for the diagnosis of acute abdominal pathology. However, coronal reformations improved the diagnostic confidence for all readers but most significantly for the least experienced. Therefore, radiology departments with residents should consider routinely generating coronal images in patients with acute abdominal pain.

OBJECTIVE The aim of the study was to evaluate objective and subjective image qualities of virtual monoenergetic imaging (VMI) in dual-source dual-energy computed tomography (DECT) and optimal kiloelectron-volt (keV) levels for lung cancer. METHODS Fifty-nine lung cancer patients underwent chest DECT. Images were reconstructed as VMI series at energy levels of 40, 60, 80, and 100 keV and standard linear blending (M_0.3) for comparison. Objective and subjective image qualities were assessed. RESULTS Lesion contrast peaked in 40-keV VMI reconstructions (2.5 ± 2.9) and 60 keV (1.9 ± 3.0), which was superior to M_0.3 (0.5 ± 2.7) for both comparisons (P < 0.001). Compared with M_0.3, subjective ratings were highest for 60-keV VMI series regarding general image quality (4.48 vs 4.52; P = 0.74) and increased for lesion demarcation (4.07 vs 4.84; P < 0.001), superior to all other VMI series (P < 0.001). Image sharpness was similar between both series. Image noise was rated superior in the 80-keV and M_0.3 series, followed by 60 keV. CONCLUSIONS Virtual monoenergetic imaging reconstructions at 60-keV provided the best combination of subjective and objective image qualities in DECT of lung cancer.

This investigation aimed to evaluate the impact on treatment regimen and clinical outcome of dual-energy computed tomography (DECT) in patients with suspected gouty arthritis.We retrospectively analyzed electronic medical records (EMR) of 39 patients (36 male, 3 female; age range, 36-85 years) who underwent DECT of peripheral joints because of suspected gouty arthritis. We assessed the prior medical history, lab results, treatment regimen, and medications before and after DECT, and changes in subjective severity of symptoms as stated by patients in the EMR. The presence of monosodium urate (MSU) crystals in the index joint was verified with DECT.Several patients had a prior diagnosis of gout (n = 9), hyperuricemia (n = 6), rheumatoid arthritis (n = 3), or psoriatic arthritis (n = 3). Elevated uric acid blood levels were detected in 32 patients (82%) before DECT. On DECT, MSU crystals were detected in 23 patients (59%). Of the 36 cases, the current treatment regimen was modified after DECT to gout-specific therapy in 22 cases and other rheumatic diseases were targeted in 14 cases. Several medications were prescribed more frequently based after DECT compared to before DECT imaging, including steroids (n = 20 vs. n = 12, respectively), colchicine (n = 13 vs. n = 4, respectively), and urate-lowering medication (n = 18 vs. n = 11, respectively). A subjective reduction of clinical symptoms during cumulative follow-up was reported by 34 patients (87.2%).Both positive and negative findings of MSU crystals on DECT have a significant impact on the treatment regimen and clinical outcome of patients with suspected gouty arthritis and facilitate differentiation from other rheumatic diseases.

To evaluate software for automatic segmentation, labeling and reformation of anatomical aligned axial images of the thoracolumbar spine on CT in terms of accuracy, potential for time savings and workflow improvement.77 patients (28 women, 49 men, mean age 65.3±14.4 years) with known or suspected spinal disorders (degenerative spine disease n=32; disc herniation n=36; traumatic vertebral fractures n=9) underwent 64-slice MDCT with thin-slab reconstruction. Time for automatic labeling of the thoracolumbar spine and reconstruction of double-angulated axial images of the pathological vertebrae was compared with manually performed reconstruction of anatomical aligned axial images. Reformatted images of both reconstruction methods were assessed by two observers regarding accuracy of symmetric depiction of anatomical structures.In 33 cases double-angulated axial images were created in 1 vertebra, in 28 cases in 2 vertebrae and in 16 cases in 3 vertebrae. Correct automatic labeling was achieved in 72 of 77 patients (93.5%). Errors could be manually corrected in 4 cases. Automatic labeling required 1min in average. In cases where anatomical aligned axial images of 1 vertebra were created, reconstructions made by hand were significantly faster (p0.05). Automatic reconstruction was time-saving in cases of 2 and more vertebrae (p0.05). Both reconstruction methods revealed good image quality with excellent inter-observer agreement.The evaluated software for automatic labeling and anatomically aligned, double-angulated axial image reconstruction of the thoracolumbar spine on CT is time-saving when reconstructions of 2 and more vertebrae are performed. Checking results of automatic labeling is necessary to prevent errors in labeling.

To define optimal keV settings for advanced monoenergetic (Mono+) dual-energy computed tomography (DECT) in patients with head and neck squamous cell carcinoma (SCC). DECT data of 44 patients (34 men, mean age 55.5 ± 16.0 years) with histopathologically confirmed SCC were reconstructed as 40, 55, 70 keV Mono + and M_0.3 (30 % 80 kV) linearly blended series. Attenuation of tumour, sternocleidomastoid muscle, internal jugular vein, submandibular gland, and noise were measured. Three radiologists with >3 years of experience subjectively assessed image quality, lesion delineation, image sharpness, and noise. The highest lesion attenuation was shown for 40 keV series (248.1 ± 94.1 HU), followed by 55 keV (150.2 ± 55.5 HU; P = 0.001). Contrast-to-noise ratio (CNR) at 40 keV (19.09 ± 13.84) was significantly superior to all other reconstructions (55 keV, 10.25 ± 9.11; 70 keV, 7.68 ± 6.31; M_0.3, 5.49 ± 3.28; all P

OBJECTIVES The aim of this study was to evaluate the effects on objective and subjective image quality of virtual monoenergetic reconstructions at various energy levels of dual-energy computed tomography (DECT) in patients with head and neck cancer. MATERIALS AND METHODS We included 71 (53 men, 18 women; age, 59.3 ± 12.0 years; range, 33-90 years) patients with biopsy-proven untreated primary (n = 55) or recurrent (n = 16) squamous cell carcinoma who underwent head and neck DECT. Images were reconstructed with a linear blending setting emulating 120 kV acquisition (M_0.3; 30% of 80 kV, 70% of 140 kV spectrum) and as virtual monoenergetic images with photon energies of 40, 60, 80, and 100 keV. Attenuation of lesion, various anatomic landmarks, and image noise were objectively measured, and lesion contrast-to-noise ratio (CNR) was calculated. Two independent blinded radiologists subjectively rated each image series using a 5-point grading scale regarding overall image quality, lesion delineation, image sharpness, and image noise. RESULTS Tumor attenuation peaked at 40 keV (140.2 ± 42.6 HU) followed by the 60 keV (121.7 ± 25.5 HU) and M_0.3 series (102.7 ± 22.3; all P < 0.001). However, the calculated lesion CNR was highest in the 60 keV reconstructions (12.45 ± 7.17), 80 keV reconstructions (8.66 ± 6.58), and M_0.3 series (5.21 ± 3.15; all P < 0.001) and superior to the other monoenergetic series (all P < 0.001). Subjective image analysis was highest for the 60 keV series regarding overall image quality (4.22; κ = 0.411) and lesion delineation (4.35; κ = 0.459) followed by the M_0.3 series (3.81; κ = 0.394; 3.77; κ = 0.451; all P < 0.001). Image sharpness showed no significant difference between both series (3.81 vs 3.79; P = 0.78). Image noise was rated superior in the 80 and 100 keV series (4.31 vs 4.34; P = 0.522). CONCLUSIONS Compared with linearly blended images, virtual monoenergetic reconstructions of DECT data at 60 keV significantly improve lesion enhancement and CNR, subjective overall image quality, and tumor delineation of head and neck squamous cell carcinoma.

Objectives To reveal the impact on workflow from introducing a dual-room sliding gantry CT to the trauma room for polytrauma and regularly scheduled in- outpatients with regard to efficiency and degree of capacity utilisation. Materials and methods Time analysis was performed for 30 polytrauma patients each in 2 different trauma room settings, the new trauma room comprising a sliding gantry CT, the old one a stationary single-room CT. Complete trauma room and diagnostic workup times were manually measured and compared for both groups. In a third scenario, the number of CT scans performed with one single sliding gantry CT and the two-room concept was compared to the number of CT scans performed on two separate regular CT units in a 5 days clinical routine sample. Results Patients demographics and type of CT examinations were comparable for all patient groups. The median time from patient arrival in the trauma room until beginning of CT scanning was 6 min shorter for the sliding gantry CT group (21 vs.15 min). Sliding gantry CT embedded in a two-room solution achieved 252 CT scans in 5 working days, compared to 250 CT scans on two separate regular CT units with the same man power. Conclusions Sliding gantry CT in the trauma room allows for significant time saving in the diagnostic workup of polytrauma patients and faster resumption of the regular in- outpatient's CT schedule is possible. With the same man power, the dual-room solution is able to generate the same throughput as two separate CT units.

To intra-individually compare single-portal-phase low-tube-voltage (100-kVp) computed tomography (CT) with 120-kVp images for short-term follow-up assessment of CT severity index (CTSI) of acute pancreatitis, interobserver agreement and radiation dose.We retrospectively analysed 66 patients with acute pancreatitis who underwent initial dual-contrast-phase CT (unenhanced, arterial, portal phase) at admission and short-term (mean interval 11.4 days) follow-up dual-contrast-phase dual-energy CT. The 100-kVp and linearly blended images representing 120-kVp acquisition follow-up CT images were independently evaluated by three radiologists using a modified CTSI assessing pancreatic inflammation, necrosis and extrapancreatic complications. Scores were compared with paired t test and interobserver agreement was evaluated using intraclass correlation coefficients (ICC).Mean CTSI scores on unenhanced, portal- and dual-contrast-phase images were 4.9, 6.1 and 6.2 (120 kVp) and 5.0, 6.0 and 6.1 (100 kVp), respectively. Contrast-enhanced series showed a higher CTSI compared to unenhanced images (P 0.05) but no significant differences between single- and dual-contrast-phase series (P 0.7). CTSI scores were comparable for 100-kVp and 120-kVp images (P 0.05). Interobserver agreement was substantial for all evaluated series and subcategories (ICC 0.67-0.93). DLP of single-portal-phase 100-kVp images was reduced by 41 % compared to 120-kVp images (363.8 versus 615.9 mGy cm).Low-tube-voltage single-phase 100-kVp CT provides sufficient information for follow-up evaluation of acute pancreatitis and significantly reduces radiation exposure.• Single-portal-phase CT provides sufficient evaluation for follow-up of acute pancreatitis. • Follow-up CT does not benefit from unenhanced or arterial-phase acquisition. • CT severity index scores are equal for dual-contrast-phase 100-/120-kVp acquisition (P 0.05). • 100-kVp single-portal-phase follow-up CT of acute pancreatitis significantly reduces radiation exposure.

Purpose: To evaluate the feasibility of phantomless in vivo dual-energy computed tomography (CT)-based three-dimensional (3D) bone mineral density (BMD) assessment in comparison with dual x-ray absorptiometry (DXA). Materials and Methods: This retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Data from clinically indicated dual-energy CT and DXA examinations within 2 months, comprising the lumbar spine of 40 patients, were included. By using automated dedicated postprocessing dual-energy CT software, the trabecular bone of lumbar vertebrae L1-L4 were analyzed and segmented. A mixed-effects model was used to assess the correlations between BMD values derived from dual-energy CT and DXA. Results: One hundred sixty lumbar vertebrae were analyzed in 40 patients (mean age, 57.1 years; range, 24-85 years), 21 male (mean age, 54.3 years; range, 24-85 years) and 19 female (mean age, 58.5 years; range, 31-80 years). Mean BMD of L1-L4 determined with DXA was 0.995 g/ cm², and 18 patients (45%) showed an osteoporotic BMD (T score less than 22.5) of at least two vertebrae. Mean dual-energy CT-based BMD of L1-L4 was 0.254 g/cm³. Bland-Altman analysis with mixed effects demonstrated a lack of correlation between dual-energy CT-based and DXA-based BMD values, with a mean difference of 0.7441 and 95% limits of agreement of 0.7441 +/- 0.4080. Conclusion: Dedicated postprocessing of dual-energy CT data allows for phantomless in vivo BMD assessment of the trabecular bone of lumbar vertebrae and enables freely rotatable color-coded 3D visualization of intravertebral BMD distribution.

To investigate the impact of automated attenuation-based tube potential selection on image quality and exposure parameters in polytrauma patients undergoing contrast-enhanced thoraco-abdominal CT. One hundred patients were examined on a 16-slice device at 120 kV with 190 ref.mAs and automated mA modulation only. Another 100 patients underwent 128-slice CT with automated mA modulation and topogram-based automated tube potential selection (autokV) at 100, 120 or 140 kV. Volume CT dose index (CTDIvol), dose–length product (DLP), body diameters, noise, signal-to-noise ratio (SNR) and subjective image quality were compared. In the autokV group, 100 kV was automatically selected in 82 patients, 120 kV in 12 patients and 140 kV in 6 patients. Patient diameters increased with higher kV settings. The median CTDIvol (8.3 vs. 12.4 mGy; −33 %) and DLP (594 vs. 909 mGy cm; −35 %) in the entire autokV group were significantly lower than in the group with fixed 120 kV (p

To compare non-linear and linear blending of cardiac dual-energy computed tomography (DECT) for optimal visualization of late iodine enhancement (LIE) in patients with chronic myocardial infarction (CMI). LIE–DECT data from 20 patients with known CMI were retrospectively analyzed. Images were reconstructed using non-linear blending center and width settings in the range of 0–500. Linear blending was performed with weighting factors 0.8 (80 % 100 kV, 20 % 140 kV), 0.6 and 0.3. 100-/140-kV data and blended images were analyzed. Contrast and percentage signal differences between infarcted and healthy myocardium and the left ventricle blood pool were computed. Statistical analysis was performed using repeated-measures analysis of variance and post hoc t tests. Non-linear blending showed the highest signal differences for all contrasts and analyses. Repeated-measures ANOVA tests confirmed the statistical differences between the investigated blending techniques (P

The purpose of the study was to compare the performance of late iodine-enhancement (LIE) dual-energy computed tomography (DECT) linear blending and selective myocardial iodine mapping for the detection of chronic myocardial infarction (CMI) with late gadolinium-enhancement (LGE) 3-T magnetic resonance imaging.This study was approved by the institutional review board, and the patients gave informed consent. A total of 20 patients with a history of CMI underwent cardiac LIE-DECT and LGE-MRI. Images of the LIE-DECT were reconstructed as 100 kilovolt (peak) (kV[p]), 140 kV(p), and weighted-average (WA; linear blending) images from low- and high-kilovoltage peak data using 3 different weighting factors (0.8, 0.6, 0.3). Additional color-coded myocardial iodine distribution maps were calculated. The images were reviewed for the presence of late enhancement, transmural extent, signal characteristics, infarct volume, and subjective image quality.Segmental analysis of LIE-DECT data from 100 kV(p), WA of 0.8, and WA of 0.6 showed identical results for the identification of CMI (89% sensitivity, 98% specificity, 96% accuracy) and correctly identified all segments with transmural scarring detected through LGE-MRI. Weighted average of 0.6 received the best subjective image quality rating (15/20 votes) and average measured infarct size correlated best with LGE-MRI (5.7% difference). In comparison with LGE-MRI, iodine distribution maps were susceptible to false-positive and false-negative findings (52% sensitivity, 88% specificity, 81% accuracy), overestimating quantity of transmural scars by 78% while underestimating infarct volume by 55%.Late iodine enhancement cardiac dual-energy computed tomography correlates well with LGE-MRI for detecting CMI, whereas iodine distribution analysis provides inferior accuracy. Linear blending further improves image quality and enables more precise estimation of scar volume.

To evaluate whether dual-energy computed tomography (DECT)-derived iodine content and iodine overlay could differentiate between normal, inflammatory and metastatic squamous cell carcinoma (SCC) cervical lymph nodes.This study was approved by the institutional review board. Sixteen patients with normal lymph nodes, 20 patients with enlarged nodes draining deep cervical inflammations and 23 patients with pathologically proved metastatic SCC nodes who underwent contrast enhanced DECT were retrospectively identified. Iodine content and overlay of 36 normal, 43 inflammatory and 52 metastatic lymph nodes were calculated using circular regions of interest and compared among the three groups. A receiver operating characteristic (ROC) curve was used to determine the sensitivity and specificity of iodine content and overlay for diagnosis of metastatic nodes.Iodine content (mg/ml) was significantly lower for metastatic lymph nodes (2.34 ± 0.45) than for normal (2.86 ± 0.37) and inflammatory (3.53 ± 0.56) lymph nodes, P 0.0001. Iodine overlay (HU) was also significantly lower for metastatic lymph nodes (47 ± 11.6) than normal (57.4 ± 8.2) and inflammatory nodes (69.3 ± 11.5), P 0.0001. The areas under the ROC curve for iodine content and iodine overlay were 0.923 and 0.896.DECT-derived iodine content and overlay differ significantly among normal, inflammatory and metastatic SCC cervical lymph nodes.• Derived iodine content can be calculated from contrast-enhanced dual-energy CT. • Derived iodine content and iodine overlay could help characterise cervical lymph nodes. • Iodine parameters were significantly lower in metastatic lymph nodes than normal/inflammatory lymph nodes. • Iodine content appears more sensitive than iodine overlay for lymph node characterisation.

a b s t r a c t Purpose: To assess the influence of experience and training on the proficiency in coronary CT angiography (CCTA) interpretation of practitioners with different levels of experience. Methods and materials: Nine radiologist and cardiologist observers with varying prior CCTA experience ranging from novice to expert independently analyzed two case series of 50 catheter-correlated CCTA studies for coronary artery stenosis (0%, ≤49%, 50-74%, 75-99%, or 100%). Results of the first case series were unblinded and presented along with catheter angiography results to each reader before proceeding to the second series. Diagnostic accuracy on a per-segment basis was compared for all readers and both case series, respectively. Results: Correlation coefficients between CCTA and catheter angiography initially ranged between good (r = 0.87) and poor (r = 0.26), depending on reader experience, and significantly (p < 0.05) improved in the second case series (range: r = 0.42 to r = 0.91). Diagnostic accuracy was significantly (p < 0.05) higher for more experienced readers (range: 96.5-97.8%) as compared to less experienced observers (range: 90.7-93.6%). After completion of the second case series for less experienced readers sensitivity and PPV significantly (p < 0.05) improved (range: 62.7-67.8%/51.4-84.1%), but still remained significantly (p < 0.05) lower as compared to more experienced observers (range: 89.8-93.3%/80.6-93.3%). Conclusion: The level of experience appears to be a strong determinant of proficiency in CCTA interpreta- tion. Limited one-time training improves proficiency in novice readers, but not to clinically satisfactory levels.

A high-pitch dual-source CT (DSCT) was compared to a standard single-source CT protocol in terms of dose and image quality for malignant lymphoma staging.Data from 43 patients who underwent DSCT (group 1) of the neck for staging of malignant lymphoma and 40 patients who underwent regular single source CT (group 2) were investigated retrospectively. Volume CT dose index (CTDIvol), dose length product (DLP), background noise (BN), attenuation values, signal-to-noise-ratio (SNR), scan time, effective tube current-time product (eff. mAs), subjective diagnostic image quality and artifact burden were compared.CTDIvol (5.5 ± 0.8 mGy vs. 12.4 ± 1.4 mGy), DLP (172 ± 27 mGycm vs. 344 ± 60 mGycm, p0.0001), eff. mAs (98 ± 15 mAs vs. 183 ± 20 mAs, p0.0001) and scan time (0.64 ± 0.05 s vs. 8.21 ± 0.72 s) were lower for group 1. BN was higher (p0.001) for group 1 with a mean difference of 2.6 HU. SNR for sternocleidomastoid and pectoral muscle was lower (6.6-12.3 vs. 7.8-19.1) for group 1. Subjective image quality (1.55 ± 0.6 vs. 1.42 ± 0.5) and artifact burden (1.62 ± 1.0 vs. 1.57 ± 0.9) were not rated significantly different (p=0.47 and p=0.80) with a good inter-observer agreement (κ=0.59-0.90).High-pitch DSCT allows reduction of patient dose for cervical lymphoma staging while diagnostic image quality is preserved.

Enlargement and dysfunction of the right ventricle (RV) is a sign and outcome predictor of many cardiopulmonary diseases. Due to the complex geometry of the RV exact volumetry is cumbersome and time-consuming. We evaluated the performance of prototype software for fully automated RV segmentation and volumetry from cardiac CT data. In 50 retrospectively ECG-gated coronary CT angiography scans the endsystolic (RVVmin) and enddiastolic (RVVmax) volume of the right ventricle was calculated fully automatically by prototype software. Manual slice segmentation by two independent radiologists served as the reference standard. Measurement periods were compared for both methods. RV volumes calculated with the software were in strong agreement with the results from manual slice segmentation (Bland–Altman r = 0.95–0.98; p < 0.001; Lin’s correlation Rho = 0.87–0.96, p < 0.001) for RVVmax and RVVmin with excellent interobserver agreement between both radiologists (r = 0.97; p < 0.001). The measurement period was significantly shorter with the software (153 ± 9 s) than with manual slice segmentation (658 ± 211 s). The prototype software demonstrated very good performance in comparison to the reference standard. It promises robust RV volume results and minimizes postprocessing time.

The visualization of myocardial viability is one of the most relevant applications of cardiovascular imaging. There are several novel techniques to assess myocardial viability using CT. This chapter will give an overview of these techniques and detail the supporting experimental and clinical evidence.

The purpose of this study is to evaluate the effect of arterial input selection on perfusion CT parameters of head and neck tumors.Perfusion calculations were done for 50 cases using deconvolution-based software. Peak enhancement values of the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA) were recorded. Blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface area product were calculated using ipsilateral ECA, ipsilateral ICA, and contralateral ICA as input arteries. Values were compared using Wilcoxon's matched pair test and Pearson's correlation coefficients (r).A highly significant correlation was observed between peak enhancement values of the ICA and ECA (r = 0.97; p0.0001). A high correlation was observed between perfusion calculations obtained using ipsilateral ICA and ECA (BF, r = 0.98; BV, r = 0.92; MTT, r = 0.91; and permeability surface area product, r = 0.89), ipsilateral and contralateral ICA (BF, r = 0.97; BV, r = 0.95; MTT, r = 0.93; and permeability surface area product, r = 0.89), as well as left and right ICA (BF, r = 0.97; BV, r = 0.95; MTT, r = 0.94; and permeability surface area product, r = 0.88). All correlations were statistically significant (p0.0001). No significant differences were observed between perfusion calculations obtained using ipsilateral ICA versus ECA, ipsilateral versus contralateral ICA, or left versus right ICA (p0.05).Arterial input selection has no significant effect on perfusion CT calculation of head and neck cancer. For standardization and simplification of postprocessing, we recommend the use of the ICA instead of the ECA as the arterial input because of its better visualization, perpendicular course, and larger caliber, all of which decrease partial volume effects.

Purpose To determine the difference in radiation dose between non-enhanced (NECT) and contrast-enhanced (CECT) chest CT examinations contributed by contrast material with different scanner generations with automatic exposure control (AEC). Methods & materials Each 42 adult patients received a NECT and CECT of the chest in one session on a 16-, 64- or 128-slice CT scanner with the same scan protocol settings. However, AEC technology (Care Dose 4D, Siemens) underwent upgrades in each of the three scanner generations. DLP, CTDIvol and image noise were compared. Results Although absolute differences in image noise were very small and ranged between 10 and 13 HU for NECT and CECT in median, the differences in image noise and dose (DLP: 16-slice:+2.8%; 64-slice:+3.9%; 128-slice:+5.6%) between NECT and CECT were statistically significant in all groups. Image noise and dose parameters were significantly lower in the most recent 128-slice CT generation for both NECT and CECT (DLP: 16-slice:+35.5–39.2%; 64-slice:+6.8–8.5%). Conclusion The presence of contrast material lead to an increase in dose for chest examinations in three CT generations with AEC. Although image noise values were significantly higher for CECT, the absolute differences were in a range of 3 HU. This can be regarded as negligible, thus indicating that AEC is able to fulfill its purpose of maintaining image quality. However, technological developments lead to a significant reduction of dose and image noise with the latest CT generation.

To prospectively compare the accuracy of coronary CT angiography (CCTA) and conventional coronary angiography (CCA) for stenosis detection using composite findings from both tests as an enhanced reference standard.One hundred thirteen patients underwent CCTA and CCA. Per-segment and per-patient accuracy of CCTA compared with initial CCA interpretation were determined. Angiographers were then unblinded to the CCTA results and re-evaluation of the CCA studies was performed with knowledge of CCTA findings, which was used as an enhanced reference standard to compare the diagnostic accuracy of CCTA versus CCA.When using the enhanced reference standard instead of initial CCA interpretation, CCTA accuracy for identifying segments (patients) with ≥50% stenosis increased from 97.7% (96.5%) to 98.1% (98.2%), sensitivity from 90.5% (100%) to 90.8% (100%), and specificity from 98.4% (94.3%) to 98.9% (97.1%). CCTA identified six segments and two patients with stenoses ≥50% missed on initial CCA interpretation. Compared with the enhanced reference standard the accuracies of CCTA and of initial CCA interpretation were not different (p = 0.87).CCTA compares favourably with CCA for stenosis detection. Use of a composite reference standard combining findings from both tests can control for the effect of false-negative CCA results when evaluating the accuracy of CCTA.

Background Traditional limitations of cardiac CT are related to image noise, blooming artifacts from calcifications and stents, and radiation exposure. We evaluated whether these limitations can be ameliorated by the use of iterative reconstruction in image space (IRIS) instead of traditional filtered back projection (FBP) image reconstruction techniques. Methods We compared image reconstruction with the use of IRIS with traditional FBP for their effect on image quality, noise, volume of heavy coronary artery calcifications, and stents as a measure of "blooming" artifacts, and radiation dose at cardiac CT. The radiation dose comparison was performed as a matched pair analysis, whereas all other comparisons were performed within the same group of patients. Results The subjective image quality of IRIS reconstructions was rated higher than FBP reconstructions. Image noise was lower with IRIS than with FBP. The volume of stents and heavy coronary artery calcifications measured lower in IRIS reconstructed series compared with FBP. Similar levels of image noise were achieved with 80/100 kVp of tube voltage with IRIS compared with 120 kVp and FBP, resulting in a 62% reduction in effective dose. Conclusion Our preliminary experiences suggest that IRIS incrementally improves the CT evaluation of coronary arteries, especially in challenging scenarios. Substantial radiation reduction seems feasible without associated increases in image noise.

To investigate the role of perfusion defect (PD) size on dual energy CT pulmonary blood volume assessment as predictor of right heart strain and patient outcome and its correlation with d-dimer levels in acute pulmonary embolism (PE).53 patients with acute PE who underwent DECT pulmonary angiography were retrospectively analyzed. Pulmonary PD size caused by PE was measured on DE iodine maps and quantified absolutely (VolPD) and relatively to the total lung volume (RelPD). Signs of right heart strain (RHS) on CT were determined. Information on d-dimer levels and readmission for recurrent onset of PE and death was collected.D-dimer level was mildly (r = 0.43-0.47) correlated with PD size. Patients with RHS had significantly higher VolPD (215 vs. 73 ml) and RelPD (9.9 vs. 2.9%) than patients without RHS (p 0.003). There were 2 deaths and 1 readmission due of PE in 18 patients with5% RelPD, while no such events were found for patients with5% RelPD.Pulmonary blood volume on DECT in acute PE correlates with RHS and appears to be a predictor of patient outcome in this pilot study.

The purpose of this article is to compare the performance of dual-energy CT with that of 3-T MRI with late enhancement for the detection of chronic myocardial infarction during first-pass coronary CT angiography (CTA).Thirty-six patients underwent coronary CTA for the assessment of coronary bypass graft patency on a first-generation dual-source CT scanner in dual-energy mode. Gray-scale images (100 kV, 140 kV, and blended virtual 120 kV) were assessed for areas of hypodense myocardium during the arterial phase. In addition, a color-coded map of myocardial iodine distribution was calculated from the dual-energy data for perfusion analysis. Dual-energy CT data were compared with data from 3-T MRI with late enhancement, which served as the reference standard for scar detection using the American Heart Association's 17-segment model of the left ventricle.One hundred one (17%) of 612 myocardial segments in 22 (61%) of 36 patients showed late enhancement on MRI. Although myocardial iodine mapping was prone to artifacts, mostly arising from sternal wires (70% sensitivity), 100-kV gray-scale images showed the highest sensitivity (80%) for the detection of myocardial scar. Blended virtual 120-kV images with lower noise and higher resolution had the best diagnostic accuracy (77% sensitivity, 97% specificity, 85% positive predictive value, 96% negative predictive value, and 94% accuracy).Detection of chronic myocardial infarction on color-coded iodine distribution analysis with first-generation dual-energy CT is impeded by thoracic metallic devices. This group of patients benefits more from adequate blending of high- and low-kilovoltage gray-scale images. Further technical improvements are desirable to lower artifact burden and improve sensitivity on myocardial iodine distribution mapping.

Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose.Examinations were performed on a second-generation dual-source CT with a pitch factor of 3.0 (dual-source mode). Images were compared with those with a pitch factor of 0.9 on the same system (single-source mode) and with those of 16-slice CT. Image quality was evaluated by four blinded readers using a 5-point scale (1=poor, 5=excellent). Comparison of the dose length product (DLP) was used to estimate radiation exposure.Seventy-three consecutive patients underwent imaging with the proposed CT protocols. The viewers rated the image quality of the dual-source image sets as nearly as good (3.62) as the single-source images on the same device (4.18) and those on 16-slice CT (3.7). DLP was cut to half of the dose [51 mGycm vs. 97.8 mGycm vs. 116.9 mGycm (p0.01)].Using the proposed dual-source mode when examining the paranasal sinus, diagnostic image quality can be achieved while drastically lowering the patient's radiation exposure.

To compare the dose estimates and image quality of Dual Energy CT (DECT), Dual Source CT (DSCT) and 16-slice CT for coronary CT angiography (cCTA). Sixty-eight patients were examined with 16 - slice MDCT (group 1), 68 patients with DSCT (group 2) and 68 patients using DSCT in dual energy mode (DECT group 3). CT dose index volume, dose length product, effective dose, signal-to-noise, and contrast-to-noise ratio were compared. Subjective image quality was rated by two observers, blinded to technique. The mean estimated radiation dose of all patients investigated on a 16 - slice MDCT was 12 ± 3.59 mSv, for DSCT in single energy 9.8 ± 4.77 mSv and for DECT 4.54 ± 1.87 mSv. Dose for CTA was significantly lower in group 3 compared to group 1 and 2. The image noise was significantly lower in Group 2 in comparison to group 1 and group 3. There was no significant difference in diagnostic image quality comparing DECT and DSCT. cCTA shows better dose levels at both DECT and DSCT compared to 16-slice CT. Further, DECT delivers significantly less dose than regular DSCT or single source single energy cCTA while maintaining diagnostic image quality.

To retrospectively compare a split-bolus contrast medium injection protocol with a biphasic and a monophasic protocol in terms of visualization of the right and left heart, contrast medium-related streak artifacts, and level of attenuation in the cardiac chambers and coronary arteries at coronary computed tomographic (CT) angiography.The human research committee approved this HIPAA-compliant study and waived informed consent. Seventy-five patients had undergone 64-section coronary CT angiography: 25 were injected by using a monophasic, contrast-medium-only protocol with a single-syringe injector; 25 were injected by using a biphasic protocol with a dual-syringe injector; and 25 were injected by using a split-bolus protocol with a dual-syringe injector and an initial bolus of contrast medium followed by 50 mL of a 70%:30% saline-to-contrast medium mixture and a 30-mL saline chaser. Two radiologists rated the visualization of right and left heart structures and the degree of streak artifacts. One observer performed attenuation measurements of the cardiac chambers and of the coronary arteries. Data were analyzed with one-way analysis of variance and Duncan post-hoc multiple comparison procedures.Data for 27 women and 48 men (mean age, 62 years) were included. Mean contrast medium attenuation in the right heart was significantly (P.001) higher in the split-bolus group than in the biphasic injection group but was significantly (P.001) lower than in the monophasic injection group. For the left heart and the coronary arteries, there were no significant differences among the three groups. Artifacts occurred less frequently (P.001) in the biphasic and split-bolus groups than in the monophasic group. Visualization of right heart structures was rated significantly (P.05) better in the split-bolus group than in the two other groups, while there was no difference for visualization of left heart structures.Split-bolus injection provides sufficient attenuation for visualization of the right heart, while streak artifacts from high-attenuation contrast material can generally be avoided and arterial attenuation is maintained.

Owing to ongoing technical refinements and intense scientific and clinical evaluations, computed tomography (CT) of the heart has left the research realm and matured into a clinical application that is about to fulfill its promise to replace invasive cardiac catheterization in selected patient populations. CT coronary angiography is technically more challenging than other CT applications owing to the nature of its target, the continuously moving heart. Rapid technical developments in this field require constant adaptation of acquisition protocols. These challenges, however, are in no way insurmountable for users with knowledge of the general CT technique. The intent of this communication is to provide those interested in and involved with coronary CT angiography with a step-by-step "manual" describing the authors' approach to performing coronary CT angiography. Included are considerations regarding appropriate patient selection, patient medication, radiation protection, contrast enhancement, acquisition and reconstruction parameters, image display and analysis techniques, and the radiology report. The recommendations are based on the authors' experience, which spans the evolution of multi-detector row CT for cardiac applications, from its beginning to the advent of the most current generations of 64-section and dual-source CT technologies, which they believe herald the entrance of this examination into routine clinical practice.

We sought to assess retrospectively the added value of coronal reformations from isotropic voxels obtained with 64-slice multidetector row computed tomography (CT) of the acute abdomen.This retrospective study was approved by the institutional review board and informed consent was waived. Multidetector helical 64-section CT (section thickness, 0.6 mm; pitch 1.75; table speed 35 mm/sec) was performed in 100 patients (60 women and 40 men; age range, 9-/+85 years; mean age, 45.2 years) with acute nontraumatic abdominal pain who had been referred from the emergency department. Axial images were reconstructed with 5-mm-thick sections at 5-mm intervals. The second data set was reformatted coronally, with 3-mm-thick sections at 3-mm intervals. Four independent, blinded readers with various level of training interpreted first the axial scans alone and then followed immediately by the coronal scans. Confidence in the visualization of anatomy and pathology was scored on a 5-point scale. The final diagnosis was determined by surgical and pathologic reports and by clinical follow-up in those who did not undergo surgery.Based upon the individual patient's clinical history and other comorbid factors, 92 patients received intravenous contrast and 90 patients received oral contrast. In 45 patients, no CT abnormalities were detected for an explanation of the abdominal pain. Mean sensitivity and specificity of axial CT alone were 92.5% and 91%, respectively. No significant differences in sensitivity and specificity were observed for the use of combined axial and coronal images. For the most inexperienced reader, the coronal reformations were helpful in 95% of cases, while for the most experienced reader, the coronal reformations were helpful in 35% of the cases. The coronal images were deemed helpful in an average of 62.3% of the cases for the four readers. However, diagnosing subtle pathology in the abdominal wall was difficult on coronal reformations alone. Overall, coronal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal abdominal structures and in the diagnosis of abdominal pathology.Axial and coronal reformations of 64-section multidetector row CT have equal sensitivity and specificity for the diagnosis of acute abdominal pathology. However, coronal reformations improved the diagnostic confidence for all readers but most significantly for the least experienced. Therefore, radiology departments with residents should consider routinely generating coronal images in patients with acute abdominal pain.