Safe, effective and durable epicardial left atrial appendage clip occlusion in patients with atrial fibrillation undergoing cardiac surgery: first long-term results from a prospective device trial.

OBJECTIVES: Atrial fibrillation (AF) is a significant risk factor for embolic stroke originating from the left atrial appendage (LAA). This is the first report of long-term safety and efficacy data on LAA closure using a novel epicardial LAA clip device in patients undergoing cardiac surgery. METHODS: Forty patients with AF were enrolled in this prospective 'first-in-man' trial. The inclusion criterion was elective cardiac surgery in adult patients with AF for which a concomitant ablation procedure was planned. Intraoperative transoesophageal echocardiography (TEE) was used to exclude LAA thrombus at baseline and evaluate LAA perfusion after the procedure, while computed tomography (CT) was used for serial imagery workup at baseline, 3-, 12-, 24- and 36-month follow-up. RESULTS: Early mortality was 10% due to non-device-related reasons, and thus 36 patients were included in the follow-up consisting of 1285 patient-days and mean duration of 3.5 ± 0.5 years. On CT, clips were found to be stable, showing no secondary dislocation 36 months after surgery. No intracardial thrombi were seen, none of the LAA was reperfused and in regard to LAA stump, none of the patients demonstrated a residual neck >1 cm. Apart from one unrelated transient ischaemic attack (TIA) that occurred 2 years after surgery in a patient with carotid plaque, no other strokes and/or neurological events demonstrated in any of the studied patients during follow-up. CONCLUSION: This is the first prospective trial in which concomitant epicardial LAA occlusion using this novel epicardial LAA clip device is 100% effective, safe and durable in the long term. Closure of the LAA by epicardial clipping is applicable to all-comers regardless of LAA morphology. Minimal access epicardial LAA clip closure may become an interesting therapeutic option for patients in AF who are not amenable to anticoagulation and/or catheter closure. Further data are necessary to establish LAA occlusion as a true and viable therapy for stroke prevention. CLINICAL TRIAL REGISTRATION: The trial is registered at www.ClinicalTrials.gov, reference: NCT00567515.

Intramural aortic abscess mimicking chronic aortic dissection.

A 77-year-old patient was referred for progressive fatigue and dyspnea on exertion. Preoperative imaging evaluations including transthoracic echocardiography and computed tomography were suggestive of a chronic ascending aortic dissection with an intramural hematoma. Intraoperatively, the intramural structure was identified as an abscess cavity.

Dual-energy CT with tin filter technology for the discrimination of renal lesion proxies containing blood, protein, and contrast-agent. An experimental phantom study.

PURPOSE: To differentiate proxy renal cystic lesions containing protein, blood, iodine contrast or saline solutions using dual-energy CT (DECT) equipped with a new tin filter technology (TFT). MATERIALS AND METHODS: 70 proxies (saline, protein, blood and contrast agent) were placed in unenhanced and contrast-enhanced kidney phantoms. DECT was performed at 80/140 kV with and without tin filtering. Two readers measured the CT attenuation values in all proxies twice. An 80/140 kV ratio was calculated. RESULTS: All intra- and interobserver agreements were excellent (r = 0.93-0.97; p < 0.001). All CT attenuation values were significantly higher in the enhanced than in the unenhanced setting (p < 0.05; average increase, 12.5 ± 3.6 HU), while the ratios remained similar (each, p > 0.05). The CT attenuation of protein, blood and contrast agent solution differed significantly with tin filtering (p < 0.01-0.05). Significant differences were found between the ratios of protein and blood compared to contrast medium solution (each, p < 0.05) and between the ratios of protein and blood in both phantoms with tin filtering (each, p < 0.05). CONCLUSION: DECT allows discrimination between a proxy renal lesion containing contrast agent and lesions containing protein and blood through their different attenuation at 80 kV and 140 kV. Further discrimination between protein and blood containing proxies is possible when using a tin filter.

High-pitch dual-source CT angiography of the aortic valve-aortic root complex without ECG-synchronization.

PURPOSE: To compare image quality and radiation dose of high-pitch computed tomography angiography(CTA) of the aortic valve-aortic root complex with and without prospective ECG-gating compared to a retrospectively ECG-gated standard-pitch acquisition. MATERIALS AND METHODS: 120 patients (mean age 68±13 years) were examined using a 128-slice dual-source CT system using prospectively ECG-gated high-pitch (group A; n=40), non-ECG-gated high-pitch (group B; n=40) or retrospectively ECG-gated standard-pitch (C; n=40) acquisition techniques. Image quality of the aortic root, valve and ascending aorta including the coronary ostia was assessed by two independent readers. Image noise was measured, radiation dose estimates were calculated. RESULTS: Interobserver agreement was good(κ=0.64-0.78). Image quality was diagnostic in 38/40 patients (group A), 37/40(B) and 38/40(C) with no significant difference in number of patients with diagnostic image quality among all groups (p=0.56). Significantly more patients showed excellent image quality in group A compared to groups B and C (each, p<0.01). Average image noise was significantly different between all groups (p<0.05). Mean radiation dose estimates in groups A and B (each; 2.4±0.3 mSv) were significantly lower compared to group C (17.5±4.4 mSv; p<0.01). CONCLUSION: High-pitch dual-source CTA provides diagnostic image quality of the aortic valve-aortic root complex even without ECG-gating at 86% less radiation dose when compared to a standard-pitch ECG-gated acquisition.

Ex vivo evaluation of coronary atherosclerotic plaques: characterization with dual-source CT in comparison with histopathology.

BACKGROUND: Identification and differentiation of coronary atherosclerotic plaques may improve risk stratification for incident coronary events. OBJECTIVE: We investigated the ability of dual-source computed tomography (CT) to depict and characterize atherosclerotic coronary plaques. METHODS: Contrast-enhanced CT was performed in 25 human heart specimens with a total of 322 histologically determined plaques. Coronary plaques were classified on CT as (1) noncalcified, mixed, or calcified and (2) by CT attenuation values. Atherosclerotic plaques were histopathologically characterized according to the Stary classification. RESULTS: CT detected 79% (245/322) of all plaques. Lesions missed by CT were generally early lesions, type I (n = 31), type II (n = 38), or type III (n = 8), according to Stary. CT detected 29% of early (Stary I-III) and 100% of advanced (Stary IV-VIII) plaques. Plaque classification as noncalcified was sensitive (100%) and specific (72%) for early, whereas classification as mixed/calcified was sensitive (92%, 89%) and specific (100%) for advanced plaques. Calcified plaques on CT were detected with high sensitivity (80%) and specificity (95%). Other subtypes were not distinguishable with CT according to the presence or absence of calcification. CT density was significantly higher for advanced (306 ± 470 HU) than for early (42 ± 14 HU; P < 0.01) plaques. The mean CT density value of type VII plaques (512 ± 349 HU) was significantly higher than those of other plaques (34-101 HU; P < 0.001). CONCLUSIONS: CT reliably depicts advanced coronary plaques and allows for the differentiation between early and advanced plaques.

Low dose high-pitch spiral acquisition 128-slice dual-source computed tomography for the evaluation of coronary artery bypass graft patency.

OBJECTIVES: To prospectively assess electrocardiography (ECG)-synchronized dual-source computed tomography (CT) in high-pitch spiral acquisition mode for the evaluation of coronary artery bypass graft (CABG) patency regarding image quality and radiation dose. MATERIALS AND METHODS: Fifty consecutive patients (47 men, age 69.6 +/- 9.6 years, body mass index 26.6 +/- 3.5 kg/m) underwent clinically indicated 128-slice dual-source CT angiography of the entire thorax for the evaluation of graft patency after CABG surgery using a prospectively ECG-synchronized high-pitch spiral acquisition mode (pitch 3.2; 100 kV tube voltage, 0.28 seconds gantry rotation time). Heart rates (HR) were noted. Image quality of the proximal anastomosis, graft body, distal anastomosis, and postanastomotic coronary artery were graded by 2 independent readers on a 3-point scale (1 = excellent, 2 = moderate, and 3 = poor/nondiagnostic). Quantitative image quality parameters (noise, contrast-to-noise ratio) were measured. Effective radiation doses were calculated. RESULTS: Mean HR was 76 +/- 19 bpm (range, 45-135 bpm). Median scan time was 0.9 seconds (range, 0.76-1.17 seconds), mean scan length was 349 +/- 38 mm (range, 294-452 mm). A total of 125 CABG (54% arterial grafts) and 465 vessel sections were analyzed. Twelve grafts were proximally occluded. Diagnostic image quality was obtained in 462 (99.4%) sections. Of those, image quality was excellent in 397 (85.4%) and moderate in 65 (14.0%). All 3 (0.6%) nondiagnostic sections affected the distal anastomosis due to motion artifacts caused by high HR. Separating the study population by the median HR of 71 bpm, image quality of the distal anastomosis regarding motion artifacts was significantly lower at high HR (P < 0.05). Interobserver agreement in grading image quality of graft segments was good (kappa = 0.77). Image noise in the aorta was 36.9 +/- 8.1, contrast-to-noise ratio was 13.1 +/- 4.2. Effective radiation dose was 2.3 +/- 0.3 mSv. CONCLUSIONS: The patency of coronary artery bypass grafts can be assessed with decreasing image quality at high HR in high-pitch prospectively ECG-synchronized thoracic 128-slice dual-source CT angiography at a low radiation dose.

Performance of dual-energy CT with tin filter technology for the discrimination of renal cysts and enhancing masses.

RATIONALE AND OBJECTIVES: To assess the performance of dual-energy computed tomography (DECT) equipped with the new tin filter technology to classify phantom renal lesions as cysts or enhancing masses. MATERIALS AND METHODS: Forty spherical lesion proxies ranging in diameter from 6 to 27 mm were filled with either distilled water (n = 10) representing cysts or titrated iodinated contrast solutions with a concentration of 0.45 (n = 10), 0.9 (n = 10), and 1.8 mg/mL (n = 10) representing enhancing masses. The lesion proxies were placed in a 12-cm diameter renal phantom containing minced beef and submerged in a 28-cm water bath. DECT was performed using the new dual-source CT system (Definition Flash, Siemens Healthcare, Forchheim, Germany) allowing for an improved energy separation by using a tin filter. DECT was performed at tube voltages of 140/80 kV without the tin filter (protocol A) and with tin filter (protocol B). The tube current time product was selected in each protocol to achieve a constant CTDI (computed tomography dose index) with both protocols of 19 mGy (full dose), 9.5 mGy (half dose), and 4.8 mGy (quarter dose). Two blinded readers classified each lesion as a cyst or enhancing mass by using iodine overlay (IO) images. One reader measured the CT numbers of each lesion at 120 kV, in the IO, linear blending (LB), and virtual noncontrast (VNC) images. RESULTS: The CT numbers of the lesions at 120 kV were 0.1 +/- 0.7 HU (0 mg iodine/mL), 9.1 +/- 0.7 HU (0.45 mg/mL), 18.1 +/- 1.4 HU (0.9 mg/mL), and 37.6 +/- 1.6 HU (1.8 mg/mL). Mean diameter of the lesion proxies filled with water or different iodine concentrations was similar (P = 0.38). Image noise was not significantly different in protocols A and B at the corresponding dose levels. At full dose, protocol A had a sensitivity of 93% and a specificity of 60% for discriminating renal lesions. Sensitivity and specificity declined to 84% and 38% at quarter dose. In protocol B, sensitivity was 100% and specificity was 90% at full dose and 93% and 70% at quarter dose. All misclassifications occurred in cyst or low iodine concentration (0.45 mg/mL) lesion proxies. The differences between CT numbers at 120 kV and in the IO, VNC, and AW (average weighted) images were significantly lower in protocol B compared to protocol A (each P < .05). CONCLUSIONS: DECT using the tin filter results in an improved sensitivity and specificity for discriminating renal cysts from enhancing masses in a kidney phantom model and demonstrates higher dose efficiency as compared to former dual energy technology without tin filters.

Combined cardiac CT and MRI for the comprehensive workup of hemodynamically relevant coronary stenoses.

OBJECTIVE: The purpose of our study was to prospectively evaluate the accuracy of a comprehensive assessment of coronary artery disease (CAD) with prospectively ECG-gated coronary CT angiography (CTA) and perfusion-cardiac MRI for the detection of hemodynamically relevant coronary stenoses. SUBJECTS AND METHODS: Forty-seven consecutive patients underwent k-space and time broad-use linear acquisition speed-up technique accelerated perfusion-cardiac MRI at 1.5 T and dual-source coronary CTA. Catheter coronary angiography (CA), coronary CTA, and perfusion-cardiac MRI were all performed within a median time interval of 7.5 days. Detection of hemodynamically relevant stenoses by the combination of coronary CTA plus perfusion-cardiac MRI was compared with the combination of CA plus perfusion-cardiac MRI, the latter serving as the standard of reference. RESULTS: CA identified stenoses in 75 of 141 coronary arteries (53.2%) in 33 of 47 patients (70.2%). Cardiac MRI revealed perfusion defects in 30 of 47 patients (63.8%). Image quality of coronary CTA was diagnostic in 635 of 638 segments (99.5%). Coronary CTA revealed stenoses greater than 50% in 76 of 141 coronary arteries (53.9%) of 33 of 47 patients (70.2%). Sensitivity, specificity, negative and positive predictive value, and accuracy of coronary CTA and perfusion-cardiac MRI versus CA and perfusion-cardiac MRI for the detection of hemodynamically relevant stenoses were 96.7%, 100%, 94.4%, 100%, and 97.9%, respectively. CONCLUSION: The combination of coronary CTA and perfusion-cardiac MRI shows diagnostic performance comparable to that of CA and perfusion-cardiac MRI. Preliminary data suggest that coronary CTA may replace CA in the diagnosis of hemodynamically relevant CAD.

High-pitch dual-source CT angiography of the thoracic and abdominal aorta: is simultaneous coronary artery assessment possible?

OBJECTIVE: The purpose of this study was to prospectively evaluate the average heart rate and heart rate variability required for diagnostic imaging of the coronary arteries with high-pitch dual-source CT angiography of the thoracic and thoracoabdominal aorta. SUBJECTS AND METHODS: One hundred consecutively registered patients (82 men, 18 women; mean age, 68 +/- 13 years) underwent clinically indicated CT angiography of the thoracic (n = 33) and thoracoabdominal (n = 67) aorta with a dual-source 128-MDCT scanner in ECG-synchronized high-pitch (pitch, 3.2) data acquisition mode. No beta-blockers were administered. The image quality of the coronary arteries was graded on a 3-point scale by two independent blinded readers. The average heart rate and heart rate variability before data acquisition were noted. Effective radiation doses were calculated. RESULTS: Interobserver agreement on grade of image quality for the 1,414 coronary segments evaluated by both observers was good (kappa = 0.68). Diagnostic image quality was found for 1,375 of the 1,414 segments (97.2%) in 83 of 100 patients (83%). In 17% of the patients, image quality was nondiagnostic for at least one coronary artery segment. Average heart rate and heart rate variability (each p < 0.05) were significantly higher in patients with at least one nondiagnostic coronary segment compared with those without. All patients with an average heart rate less than 63 beats/min and heart rate variability less than 1.2 beats/min had diagnostic image quality in all coronary segments. Effective radiation doses were 2.3 +/- 0.3 mSv for thoracic and 4.4 +/- 0.5 mSv for thoracoabdominal CT angiography. The average scan times were 0.88 +/- 0.06 second for thoracic and 1.67 +/- 0.15 seconds for thoracoabdominal CT angiography. CONCLUSION: For patients with an average heart rate less than 63 beats/min and heart rate variability less than 1.2 beats/min, dual-source CT angiography of the thoracoabdominal aorta at a high pitch of 3.2 delivers diagnostic depiction of the coronary arteries at a low radiation dose.

Effect of reader experience on variability, evaluation time and accuracy of coronary plaque detection with computed tomography coronary angiography.

OBJECTIVE: To assess the effect of reader experience on variability, evaluation time and accuracy in the detection of coronary artery plaques with computed tomography coronary angiography (CTCA). METHODS: Three independent, blinded readers with three different experience levels twice labelled 50 retrospectively electrocardiography (ECG)-gated contrast-enhanced dual-source CTCA data sets (15 female, age 67.3 +/- 10.4 years, range 46-86 years) indicating the presence or absence of coronary plaques. The evaluation times for the readings were recorded. Intra- and interobserver variability expressed as kappa statistics and sensitivity, specificity, and negative and positive predictive values were calculated for plaque detection, with a consensus reading of the three readers taken as the standard of reference. A bootstrap method was applied in the statistical analysis to account for clustering. RESULTS: Significant correlations were found between reader experience and, respectively, evaluation times (r = -0.59, p < 0.05) and intraobserver variability (r = 0.73, p < 0.05). The evaluation time significantly differed among the readers (p < 0.05). The observer variability for plaque detection, compared with the consensus, varied between kappa = 0.582 and kappa = 0.802. Variability of plaque detection was significantly smaller (p < 0.05) and more accurate (p < 0.05) for the most experienced reader. CONCLUSION: Reader experience significantly correlated with observer variability, evaluation time and accuracy of coronary plaque detection at CTCA.

Long-term follow-up, computed tomography, and computational fluid dynamics of the Cabrol procedure.

OBJECTIVES: The Cabrol procedure is characterized by insertion of an ascending aortic composite graft with reimplantation of the coronary arteries by the interposition of a graft tube. Our purpose is to report the clinical long-term follow-up and computed tomographic findings in patients having undergone the Cabrol procedure and to determine blood flow in the Cabrol graft using computational fluid dynamics. METHODS: Clinical follow-up (76.6 +/- 16.6 months) and dual-source computed tomographic angiography data of 7 patients (all men, mean age 54.9 +/- 9.6 years) with 12 Cabrol grafts (left main coronary artery, n = 7; right coronary artery, n = 5) were reviewed. In 2 patients, the right coronary artery was directly reattached to the aortic graft. Computational fluid dynamics were calculated using computed tomographic data of a patient with the Cabrol procedure and compared with those in a Valsalva graft and a healthy aortic root. RESULTS: Computed tomography showed Cabrol graft occlusions to 1 of 7 (14%) left main and of 2 of 5 (40%) right coronary arteries. Six grafts to the left main and 3 to the right coronary artery were fully patent, similar to the 2 directly reattached right coronary arteries to the aortic graft. Computational fluid dynamics results show similar blood flow parameters into the coronaries for the healthy aortic root and Valsalva graft. In the Cabrol graft, a spiraling flow pattern with low flow into the right coronary artery was found (right coronary artery = 1 mL/min at both systole and diastole). CONCLUSIONS: Our study indicates low flow rates particularly in the right Cabrol graft correlating with a higher incidence of occlusions of the right as compared with the left Cabrol graft at long-term follow-up.

Characterization of urinary stones with dual-energy CT: improved differentiation using a tin filter.

PURPOSE: To assess image quality and capability of stone differentiation between UA-containing and non-UA-containing uroliths with the latest dual-energy (DE) computed tomography (CT) system equipped with a tin filter (TF) using various data acquisition parameters in a work bench model. METHODS AND MATERIALS: One hundred ten urinary stones (4.2 +/- 3.0 mm, 0.4-12 mm) of 15 compositions were examined in an ex vivo phantom, using DE dual-source CT (Definition Flash, Siemens Healthcare) equipped with a TF. Phantom was scanned in a water tank and contained stones in acrylic elliptic spheres filled with a parenchyma substitute. Scans were performed at 3 different settings: at 80 and 140 kVp without TF, at 80 and 140 kVp with TF, and at 100 and 140 kVp with TF. Tube current time products were adapted to yield constancy in CT dose indices (CTDIvol = 18.84 mGy, 18.95 mGy, and 18.90 mGy, respectively). CT numbers of urinary stones and image noise were electronically measured by placing regions of interest. DE indices (DEI) were calculated and compared using analysis of variances for repeated measures and paired t tests; image noise (IN) using the Friedman test. The stones were classified as UA-containing or non-UA-containing on color-coded images based on the DEI. Diagnostic accuracy was calculated using crystallographic analysis as standard of reference. RESULTS: Of the 110 stones (60%), 65 contained UA; 45 stones (40%) contained no UA. DEI was greatest at 80 and 140 kVp when using the TF (DEI80 kVp/TF140 kVp = 0.038 vs. DEI80 kVp/140 kVp = 0.028, DEI100 kVp/TF140 kVp = 0.025; P < 0.01). IN of high kVp acquisitions were similar (P = 0.15), whereas IN of low kVp acquisitions were significantly (P < 0.001) different being lowest at 100 kVp. The semiautomated DE software correctly classified all stones at all settings with a diagnostic accuracy of 100% (95% confidence interval: 97%-100%). CONCLUSION: DECT with TF and 80-140 kVp tube voltage settings significantly improves the discrimination between UA-containing and non-UA containing urinary stones as compared with DECT without using the TF on the basis of DEI. The 100/140 kVp setting with TF is associated with lower IN but demonstrates similar discrimination abilities as compared with 80/140 kVp setting without the use of the TF.

Dual-source versus 64-section CT coronary angiography at lower heart rates: comparison of accuracy and radiation dose.

PURPOSE: To compare the diagnostic performance and radiation doses of dual-source and 64-section computed tomographic (CT) coronary angiography for the diagnosis of significant coronary stenoses in patients with heart rates of 65 beats/min or less. MATERIALS AND METHODS: This retrospective study had local ethics committee approval; all patients gave written informed consent. Two hundred patients with heart rates of 65 beats/min or less were enrolled; 100 underwent dual-source and 100 underwent 64-section CT coronary angiography. Two blinded observers independently assessed image quality of all coronary segments by using a four-point scale and searched for significant (>50%) stenoses in each segment. Catheter angiography was used as the reference standard. Image noise was measured in the ascending aorta. Radiation doses were calculated. RESULTS: No significant differences were found regarding sex, age, body weight, cardiovascular risk profile, prevalence of stenosis, mean and variability of heart rate, Agatston score, and image noise (all P > .1) between patients in both CT coronary angiography groups. No significant difference was found in the rate of nonassessable coronary segments between dual-source (1.0%, 14 of 1405) and 64-section CT coronary angiography (1.8%, 25 of 1387; P = .08). Motion artifacts occurred significantly more often in 64-section (21 of 25) versus dual-source (five of 14, P = .004) CT coronary angiography. Segment-based accuracy and specificity were significantly higher for dual-source versus 64-section CT coronary angiography. There was no significant difference in accuracy parameters at the per-vessel and per-patient analyses. No significant difference (P = .13) was found between the effective doses of dual-source (mean +/- standard deviation, 10.9 mSv +/- 1.1) and 64-section CT (10.4 mSv +/- 1.7) coronary angiography. CONCLUSION: In patients with heart rates of 65 beats/min or less, the higher temporal resolution of dual-source CT coronary angiography results in improved accuracy and specificity for the diagnosis of significant stenoses on a per-segment level at a similar radiation dose, but provides a comparable diagnostic accuracy on a patient-based level as does 64-section coronary angiography.

Influence of calcifications on diagnostic accuracy of coronary CT angiography using prospective ECG triggering.

OBJECTIVE: The purpose of this study was to investigate the diagnostic accuracy of dual-source CT coronary angiography with prospective ECG triggering compared with catheter angiography and to determine the influence of vessel wall calcifications. SUBJECTS AND METHODS: One hundred consecutive patients (42 women and 58 men; mean age, 65.8 +/- 6.5 years) with a sinus rhythm and heart rates < 70 beats per minute were included. Two independent, blinded readers classified coronary artery segments as being of diagnostic or nondiagnostic image quality and assessed each segment with diagnostic image quality for the presence of significant coronary stenoses. Nondiagnostic segments were excluded from analysis. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for all patients and for the subgroup of patients with a low or high calcium score (group A, median Agatston score < 316; group B, > or = 316). Catheter angiography was used as the reference standard. Effective radiation dose values were calculated. RESULTS: In 89 of 100 patients (89%), 1,462 of 1,524 coronary segments (96%) were depicted with diagnostic image quality. The overall sensitivity, specificity, PPV, and NPV were 98%, 99%, 95%, and 100%, respectively. The rate of segments with nondiagnostic image quality was significantly higher (p < 0.001) in group B compared with group A. In group A, sensitivity, specificity, PPV, and NPV were 99%, 99%, 94%, and 100%, respectively, and in group B, 98%, 99%, 94%, and 99%, respectively, with no significant differences between the groups. The average effective radiation dose was 2.6 +/- 0.8 mSv (range, 1.2-4.4 mSv). CONCLUSION: Dual-source CT coronary angiography with use of prospective ECG triggering performs accurately in the assessment of coronary artery disease at low radiation doses. Diagnostic accuracy remains high despite the presence of heavy calcifications but is associated with an increased rate of nondiagnostic segments.

Radiation dose of cardiac dual-source CT: the effect of tailoring the protocol to patient-specific parameters.

OBJECTIVE: To determine the radiation doses and image quality of different dual-source computed tomography coronary angiography (CTCA) protocols tailored to the heart rate (HR) and body mass index (BMI) of the patients. MATERIALS AND METHODS: Two hundred consecutive patients (68 women; mean age 61+/-9 years) underwent either helical CTCA with retrospective ECG-gating or sequential CT with prospective ECG-triggering: 50 patients (any BMI, any HR) were examined with a standard, non-tailored protocol (helical CTCA, 120 kV, 330 mAs), whereas the other 150 patients were examined with a tailored protocol: 40 patients (group A, BMI70 bpm) with helical CTCA (100 kV, 220 mAs), 28 patients (group C, BMI>25 kg/sqm, HR25 kg/sqm, HR>70 bpm) with helical CTCA (120 kV, 330 mAs). The effective radiation dose estimates were calculated from the dose-length-product for each patient. Image quality was classified as being diagnostic or non-diagnostic in each coronary segment. RESULTS: Image quality was diagnostic in 2403/2460 (98%) and non-diagnostic in 57/2460 (2%) of all coronary segments. No significant differences in image quality were found among all five CTCA protocols (p=0.78). The non-tailored helical CTCA protocol was associated with a radiation dose of 9.0+/-1.0 mSv, being significantly higher compared to that using sequential CTCA (group A: 1.3+/-0.3 mSv, p<0.001; group C: 2.9+/-0.6 mSv, p<0.001), and helical CTCA at reduced tube voltage and tube current (group B: 4.2+/-0.6 mSv, p<0.01). No significant differences were found compared to the non-tailored CTCA protocol in patients with HR>70 bpm (group D: 8.5+/-0.9 mSv, p=0.51). CONCLUSIONS: Dual-source CTCA is associated with radiation doses ranging between 1.3 and 9.0 mSv, depending on the protocol used. Tailoring of the CTCA protocol to the HR and BMI of the individual patient results in dose reductions of up to 86%, while maintaining a diagnostic image quality of the examination.

Immunohistochemical differentiation and localization analysis of sweat glands in the adult human axilla.

BACKGROUND: The classic concept of axillary glands differentiates between eccrine glands, producing abundant clear, nonodorous sweat; and apocrine glands, excreting small amounts of turbid, odorous milky sweat. A third type of sweat glands, the "apoeccrine" glands, were recently identified. To define the different types of sweat glands and their location and number, the authors carried out a prospective histologic study on adult human axillary skin, including various immunohistochemical markers. METHODS: Forty-three consecutive Caucasian, subjectively normhidrotic patients, who underwent a surgical procedure in the axilla unrelated to the axillary glands, were included in the study. For verification of normhidrosis, the gravimetric test was carried out by measuring the amount of sweat secretion per minute. Then, a 1 x 1-cm measuring piece of skin and subcutaneous tissue was excised in the apex of the axilla, divided into three samples--altogether, 129 samples--and processed for histologic examination. RESULTS: In the dermis, the authors found only very few eccrine (average, 0.3 gland/cm in only 12 percent of all patients) and apocrine glands (average, 0.1 gland/cm in only 4.7 percent of patients), and no apoeccrine glands in any patient. In the subcutaneous tissue, the mean number of glands per centimeter squared was 10 for the eccrine glands, nine for the apocrine glands, and six for the apoeccrine glands. CONCLUSIONS: In the authors' Caucasian subjects, all or most of the sweat glands were found in the subcutaneous tissue near the border to the dermis and not in the dermis. For extremely hyperfunctioning sweat glands, the authors recommend less radical surgical methods, with the preservation of skin, based on the knowledge that most glands are localized in the subcutaneous tissue.