Computed tomography of the lung in the high-pitch mode: is breath holding still required?

OBJECTIVES: To prospectively investigate whether the high-pitch mode (HPM) for computed tomography (CT) enables the diagnostic visualization of the lung parenchyma without suspended respiration. MATERIALS AND METHODS: A total of 40 consecutive patients (age, 67 ± 11 years) underwent 128-slice dual-source CT of the chest including nonenhanced, arterial, and venous phase of contrast. CT was performed in the HPM with a pitch of 3.2 during continuous breathing (group A) and during breath-hold (group B), and at standard pitch of 1 during deep-inspiratory breath-hold (group C). The 3 protocols were scanned in a random order in each patient. Two blinded readers independently assessed the image quality of 5 regions in both the lungs using a semiquantitative 3-point score. Image noise was measured as the standard deviation of attenuation. Presence and size of pulmonary nodules were noted and measured on each CT dataset. Lung volume was measured using dedicated semi-automated segmentation software. RESULTS: Interobserver agreement for image quality ratings was excellent (κ = 0.91). There were no significant differences in the number of lung regions having an image quality other than excellent between group A (2.5%) and B (1.5%, P = 0.48), whereas significantly less regions had impaired image quality in group B compared with group C (5.5%, P < 0.01). Image quality impairment in group C was because of breathing in 36% and cardiac pulsation in 64%. Image noise in group C (9 ± 2 HU) was significantly lower than that in group B (30 ± 2 HU, P < 0.001) whereas no significant difference was found between group A and B (P = 0.52). There were no significant differences for the depiction (P = 1.0) and size (P = 0.94) of lung nodules among the 3 modes. Average lung volume in group A was 75% ± 15% of that in deep inspiration (group B/C) being significantly smaller (P < 0.05). Estimated effective radiation doses in group C and group B were 5.8 ± 0.5 mSv and 1.6 ± 0.1 mSv, respectively. CONCLUSIONS: CT of the lung can be accomplished using the HPM at a low radiation dose with a diagnostic image quality even without suspended respiration.

Diagnostic accuracy of high-pitch dual-source CT for the assessment of coronary stenoses: first experience.

OBJECTIVES: The objective was to prospectively investigate the diagnostic accuracy of high-pitch (HP) dual-source computed tomography coronary angiography (CTCA) compared with catheter coronary angiography (CCA) for the diagnosis of significant coronary stenoses. METHODS: Thirty-five patients (seven women; mean age 62 ± 8 years) underwent both CTCA and CCA. CTCA was performed with a second-generation dual-source CT system permitting data acquisition at an HP of 3.4. Patients with heart rates >60 bpm were excluded from study enrolment. All coronary segments were evaluated by two blinded and independent observers with regard to image quality on a four-point scale (1: excellent to 4: non-diagnostic) and for the presence of significant coronary stenoses (defined as diameter narrowing exceeding 50%). CCA served as the standard of reference. Radiation dose values were calculated using the dose-length product. RESULTS: Diagnostic image quality was found in 99% of all segments (455/459). Non-diagnostic image quality occurred in a single patient with a sudden increase in heart rate immediately before and during CTCA. Taking segments with non-evaluative image quality as positive for disease, the sensitivity, specificity and positive and negative predictive values were 94, 96, 80 and 99% per segment and 100, 91, 88 and 100% per patient. The effective radiation dose was on average 0.9 ± 0.1 mSv. CONCLUSION: In patients with heart rates ≤60 bpm, CTCA using the HP mode of the dual-source CT system is associated with high diagnostic accuracy for the assessment of coronary artery stenoses at sub-milli-Sievert doses.

Triple rule-out CT in patients with suspicion of acute pulmonary embolism: findings and accuracy.

RATIONALE AND OBJECTIVES: The aim of this study was to prospectively investigate the diagnostic value of triple rule-out computed tomography (CT) in patients suspected of having acute pulmonary embolism (PE). MATERIALS AND METHODS: A total of 125 patients with suspicion of PE, of whom 14 patients had the additional clinical suspicion of acute aortic syndrome, underwent electrocardiogram-gated triple rule-out dual-source CT. The contrast media application protocol was adjusted to obtain a homogenous attenuation of the pulmonary arteries, thoracic aorta, and coronary arteries. The diagnostic performance of triple rule-out CT was assessed by using adjudicated discharge diagnoses as reference standards. RESULTS: A total of 161 adjudicated cardiovascular discharge diagnoses were made in the 125 patients (including all true-positive and true-negative findings): acute PE was found in 26 (21%) and was excluded by CT in 99 (79%), coronary artery disease was found in 3 (3%) and was excluded by catheter angiography in 9 (6%), left ventricular systolic dysfunction was found in 2 (2%) and was excluded by echocardiography in 8 (6%), and acute aortic syndrome was found in 5 (4%) and was excluded by CT in 9 (7%) patients. Nonvascular chest disease was found in 34 (27%) and included pneumonia (n = 17), neoplasms (n = 5), fractures/osteolysis (n = 3), pericarditis (n = 2), and post-pneumonectomy syndrome (n = 1). Triple rule-out CT was normal in 53 (42%) patients. Overall sensitivity, specificity, and positive and negative predictive value of triple rule-out CT for cardiovascular disease were 100% (95% confidence interval [CI] 90-100%), 98% (95%CI 94-100%), 95% (95%CI 82-99%), and 100% (95%CI 97-100%, respectively). CONCLUSIONS: Triple rule-out CT is feasible in patients with suspicion of PE, reveals a wide range of vascular and non-vascular chest disease, and offers an excellent overall diagnostic performance.

Conventional radiography and computed tomography of cardiac assist devices.

Patients intended for circulatory support by cardiac assist devices (CAD) usually suffer from end-stage acute or chronic heart failure. Since the introduction of CAD in 1963 by DeBakey and coworkers, the systems have gone through a substantial evolution and have been increasingly used in the intervening decades. The spectrum of CAD includes a variety of systems serving to assist the systolic function of the left ventricle, the right ventricle, or both. Conventional radiography and multislice spiral computed tomography (CT) are the most commonly used radiological techniques for imaging patients with a CAD. CT is very useful for evaluating CAD systems by using both two- and three-dimensional reconstructions of the volumetric data sets. The two techniques together allow for the comprehensive assessment of patients with devices by imaging the in- and outflow cannulae, the anastomoses, the position of the pump, as well as associated complications. A close collaboration with cardiac surgeons with expertise in the field of circulatory support is deemed necessary for adequate image interpretation. This article describes the technical diversity of the currently available CAD systems. The imaging characteristics on conventional radiography and multislice spiral CT as well as the typical complications of their use are demonstrated.

Mitral annular shape, size, and motion in normals and in patients with cardiomyopathy: evaluation with computed tomography.

OBJECTIVE: To assess prospectively, in healthy subjects and in patients with dilated cardiomyopathy (DCM) and hypertrophic obstructive cardiomyopathy (HOCM), the 3-dimensional (3D) shape, size, and motion of the mitral annulus (MA) using computed tomography (CT). MATERIALS AND METHODS: Twenty patients with no cardiac abnormalities (referred to as normals), 15 with DCM, and 15 with HOCM as determined by echocardiography underwent contrast-enhanced, retrospectively electrocardiography (ECG)-gated 64-slice CT of the heart. The MA was manually segmented in 10% steps of the RR interval with dedicated 3D software employing the point-wrap algorithm. The MA shape, area size, change of the MA area, and apicobasal MA motion throughout the cardiac cycle was determined and compared between the groups. Intercommissural distances were measured with CT and compared with findings during surgery in 9 patients undergoing ring annuloplasty. RESULTS: The MA was nonplanar in all phases and subjects, being largest in diastole and smallest in systole. The MA area was significantly (P < 0.001) larger in patients with DCM (11.5 +/- 4.1 cm/m) as compared with normals (5.5 +/- 0.9 cm/m) and HOCM (4.7 +/- 0.9 cm/m). The change of MA area throughout the cardiac cycle was significantly (P < 0.017) smaller in patients with DCM (12.2 +/- 3.3%/m) as compared with normals (20.0 +/- 7.9%/m) and HOCM (20.5 +/- 7.7%/m). The mean apicobasal motion was significantly (P < 0.017) smaller in patients with DCM (2.2 +/- 1.0 mm/m) as compared with normals (3.6 +/- 0.8 mm/m) and HOCM (2.7 +/- 0.7 mm/m). Intercommissural distances as determined by CT showed a good correlation (r = 0.68, P < 0.05) with intraoperative measurements (mean difference, 0.44 mm; limits of agreement, -2.73-3.62 mm). CONCLUSION: Our study provides in vivo human data on the 3D shape, size, and motion of the MA in healthy subjects. Significant changes in size and motion of the MA were noted in patients with HOCM.

Atrial myxomas and thrombi: comparison of imaging features on CT.

OBJECTIVE: The purpose of our study was to compare the imaging features of atrial myxomas and thrombi using CT and to assess the accuracy of CT for determining the origin of myxomas in comparison with surgical findings. MATERIALS AND METHODS: From July 2006 until June 2008, 23 patients (15 women, eight men; mean age, 63 +/- 14 years) with atrial myxomas (n = 13) and thrombi (n = 11) who underwent dual-source CT coronary angiography were included in this retrospective study. Two independent and blinded readers evaluated quantitative (CT attenuation and size) and qualitative (location, origin, shape, mobility, prolapse, and calcifications) parameters at CT. The shape and origin of myxomas were compared with the findings at surgery. RESULTS: No significant differences regarding the CT attenuation of myxomas in comparison with thrombi were found (43 +/- 14 HU vs 57 +/- 30 HU; p = 0.23). Myxomas were significantly larger than thrombi (33 +/- 16 mm vs 21 +/- 7 mm; p < 0.05). The lesions were found equally in the left and right atria (p = 0.11). The origin (p < 0.001), shape (p < 0.05), mobility (p < 0.01), and occurrence of prolapse (p < 0.01) differed significantly between the lesions. Calcifications did not differ between the lesions (p = 0.2). In comparison with surgery, the origin of myxomas was correctly evaluated by CT in 11 of 13 patients (fossa ovalis, n = 5; interatrial septum, n = 4; and lateral atrial wall, n = 2), whereas CT misclassified the origin of two myxomas (posterior and lateral wall left atria at CT vs fossa ovalis at surgery). CONCLUSION: Atrial myxomas and thrombi can be differentiated by their distinguishing features of size, origin, shape, mobility, and prolapse. CT is accurate in determining the origin of myxomas but may fail in some cases.

Multislice computed tomography in infective endocarditis: comparison with transesophageal echocardiography and intraoperative findings.

OBJECTIVES: The aim of this study was to assess the value of multislice computed tomography (CT) for the assessment of valvular abnormalities in patients with infective endocarditis (IE) in comparison with transesophageal echocardiography (TEE) and intraoperative findings. BACKGROUND: Multislice CT has recently shown promising data regarding valvular imaging in a 4-dimensional fashion. METHODS: Thirty-seven consecutive patients with clinically suspected IE were examined with TEE and 64-slice CT or dual-source CT. Twenty-nine patients had definite IE and underwent surgery. RESULTS: The diagnostic performance of CT for the detection of evident valvular abnormalities for IE compared with TEE was: sensitivity 97%, specificity 88%, positive predictive value (PPV) 97%, and negative predictive value (NPV) 88% on a per-patient basis (n = 37; excellent intermodality agreement kappa = 0.84). CT correctly identified 26 of 27 (96%) patients with valvular vegetations and 9 of 9 (100%) patients with abscesses/pseudoaneurysms compared with the intraoperative specimen. On a per-valve-based analysis, diagnostic accuracy for the detection of vegetations and abscesses/pseudoaneurysms compared with surgery was: sensitivity 96%, specificity 97%, PPV 96%, NPV 97%, and sensitivity 100%, specificity 100%, PPV 100%, NPV 100%, respectively, without significant differences as compared with TEE. Vegetation size measurements by CT correlated (r = 0.95; p <0.001) with TEE (mean 7.6 +/- 5.6 mm). The mobility of vegetations was accurately diagnosed in 21 of 22 (96%) patients with CT, but all of 4 leaflet perforations (

Triple rule-out CT in the emergency department: protocols and spectrum of imaging findings.

Triage decisions in patients suffering from acute chest pain remain a challenge. The patient's history, initial cardiac enzyme levels, or initial electrocardiograms (ECG) often do not allow selecting the patients in whom further tests are needed. Numerous vascular and non-vascular chest problems, such as pulmonary embolism (PE), aortic dissection, or acute coronary syndrome, as well as pulmonary, pleural, or osseous lesions, must be taken into account. Nowadays, contrast-enhanced multi-detector-row computed tomography (CT) has replaced previous invasive diagnostic procedures and currently represents the imaging modality of choice when the clinical suspicion of PE or acute aortic syndrome is raised. At the same time, CT is capable of detecting a multitude of non-vascular causes of acute chest pain, such as pneumonia, pericarditis, or fractures. Recent technical advances in CT technology have also shown great advantages for non-invasive imaging of the coronary arteries. In patients with acute chest pain, the optimization of triage decisions and cost-effectiveness using cardiac CT in the emergency department have been repetitively demonstrated. Triple rule-out CT denominates an ECG-gated protocol that allows for the depiction of the pulmonary arteries, thoracic aorta, and coronary arteries within a single examination. This can be accomplished through the use of a dedicated contrast media administration regimen resulting in a simultaneous attenuation of the three vessel territories. This review is intended to demonstrate CT parameters and contrast media administration protocols for performing a triple rule-out CT and discusses radiation dose issues pertinent to the protocol. Typical life-threatening and non-life-threatening diseases causing acute chest pain are illustrated.

Endoleaks after endovascular abdominal aortic aneurysm repair: detection with dual-energy dual-source CT.

PURPOSE: To assess the diagnostic performance of dual-energy dual-source computed tomography (CT) in the detection of endoleaks after endovascular abdominal aortic aneurysm (AAA) repair. MATERIALS AND METHODS: This study was local ethics board approved, and written informed consent was obtained from all patients. One hundred eighteen patients (21 women, 97 men; mean age, 74 years +/- 8 [standard deviation]) underwent follow-up dual-energy dual-source CT during the nonenhanced, arterial, and delayed phases after AAA repair. Delayed phase CT images were acquired in the dual-energy mode for reconstruction of virtual nonenhanced images. Two blinded and independent readers evaluated the data for the presence or absence of endoleaks during three reading sessions: Standard nonenhanced, arterial phase, and delayed phase images were read during session A; virtual nonenhanced, arterial phase, and delayed phase images, during session B; and virtual nonenhanced and delayed phase images, during session C. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated, with the session A image data set as the reference standard. Radiation dose parameters were estimated. RESULTS: Reading session A revealed that 52 (44%) of 118 patients had endoleaks. Overall sensitivity, specificity, NPV, and PPV for CT endoleak detection during sessions B and C were identical: 100%, 97%, 100%, and 96%, respectively. The accuracy of the session B and session C readings was not significantly different from that of the session A reading (P = .50). The effective radiation dose in the image acquisition protocol involving one dual-energy scan was significantly (P < .001) lower than the effective doses in the protocols involving standard triple-phase scanning (mean difference, 61%) and standard nonenhanced and delayed phase scanning (mean difference, 41%). CONCLUSION: Compared with standard protocols, one dual-energy dual-source CT scan performed during the delayed phase with reconstruction of virtual nonenhanced images enables detection of endoleaks after endovascular AAA repair with high accuracy and a considerably lower radiation dose.

Dual-energy computed tomography for the differentiation of uric acid stones: ex vivo performance evaluation.

We assessed the potential of dual-energy computed tomography (CT) for the differentiation between uric acid (UA)-containing and non-UA-containing urinary stones. Forty urinary stones of 16 different compositions in two sizes (or=5 mm) were examined in an ex vivo model. Thirty stones consisted of pure calcium oxalate (whewellite or wheddellite), calcium phosphate (apatite, brushite, or vaterite), ammonium magnesium phosphate (struvite), UA, ammonium acid urate, ammonium phosphate, sodium hydrogen urate, or cystine, and ten stones were of mixed composition (UA-sodium hydrogen urate, whewellite-urate, wheddellite-urate, whewellite-brushite, or whewellite-brushite-struvite). Scans were performed using dual-source CT in a dual-energy mode with the tubes simultaneously operating at 80 and 140 kV. Two readers analysed the data with respect to stone attenuation at each energy level. The stones were classified as UA- or non-UA-containing using manual attenuation measurements and software analysis results. Sensitivity, specificity, PPV, and NPV were calculated using crystallographic stone analysis as the gold standard. Twenty-six out of 40 stones (65%) contained no UA; 14 stones (35%) contained UA. When compared with UA-containing stones, the differences in attenuation values at 80 and 140 kV were significantly (P<0.001) higher in stones containing no UA. The software automatically mapped 39/40 stones (98%). Only one (2%) 2 mm UA-stone was missed. The software correctly classified all detected stones as UA- or non-UA-containing. The attenuation values of the missed stone were manually plotted into the analysis sheet which allowed for the correct classification of the stone (containing UA). Therefore, the sensitivity, specificity, PPV, and NPV for the detection of UA-containing stones was 100%. Ex vivo experience indicates that differentiation between UA- and non-UA-containing stones can be accurately performed using dual-source dual-energy CT.

Reference values for quantitative left ventricular and left atrial measurements in cardiac computed tomography.

To assess reference values for left ventricular (LV) and left atrial (LA) dimensions, global LV function, and LV-myocardial mass for cardiac CT. We examined 120 subjects undergoing a coronary angiography using 64-slice and dual-source CT. All individuals had a low cardiovascular risk, normal ECG, negative biomarkers, and a normal cardiac CT examination. All subjects had a negative medical history of cardiovascular disease both on admission and at clinical 6-month follow-up. The following measurements were obtained: septal wall thickness (SWT), posterior wall thickness (PWT), LV inner diameter (LVID), LA anterior posterior diameter (LAD(sys)), end-systolic volume (ESV), and end-diastolic volume (EDV), LV-myocardial mass (LVMM). We found significant gender-related differences for all LV dimensions (SWT(sys), SWT(dia),PWT(sys),PWT(dia),LVID(sys),LVID(dia)). LAD(sys) showed no significant difference between males and females. Significant differences were found for global LV functional parameters including ESV, EDV, and SV, whereas no significant differences were found for the EF. LV-myocardial mass parameters showed significant gender-related differences. No significant correlation was found between any of these parameters and age. All data were transferred to percentile ranks. This study provides gender-related reference values and percentiles for LV and LA quantitative measurements for cardiac CT and should assist in interpreting results.

Radiation dose estimates in dual-source computed tomography coronary angiography.

The purpose of this study was to quantify radiation dose parameters of dual-source CT coronary angiography. Eighty patients underwent contrast-enhanced, retrospectively ECG-gated dual-source CT coronary angiography with heart rate-adapted ECG pulsing using two algorithms: In 40 patients, the tube current was reduced to 20% (A(min1)) of the normal tube current (A(max)) outside the pulsing window; in 40 patients tube current was reduced to 4% (A(min2)) of A(max). Mean CTDI(vol) in the A(min1) group was 45.1 +/- 3.6 mGy; the mean CTDI(vol) in the A(min2) group was 39.1 +/- 3.2 mGy, with CTDI(vol) in the A(min2) group being significantly reduced when compared to the A(min1) group (P < 0.001). A significant negative correlation was found between CTDI(vol) and heart rate in group A(min1) (r = -0.82, P < 0.001), whereas no correlation was found between CTDI(vol) and heart rate in group A(min2) (r = -0.066). Using the conversion coefficient for the chest, dual-source CT coronary angiography resulted in an estimated mean effective dose of 8.8 mSv in the A(min1) group and 7.8 mSv in the A(min2). Radiation exposure of dual-source CT coronary angiography using an ECG-pulsing protocol reducing the tube current to 20% significantly decreases with increasing heart rates, despite using wider pulsing windows at higher heart rates. When using a protocol with reduced tube current of 4%, the radiation dose is significantly lower, irrespective of the heart rate.

Dual-energy contrast-enhanced computed tomography for the detection of urinary stone disease.

OBJECTIVES: To assess the value of dual-energy contrast-enhanced computed tomography (CT) imaging for the detection of urinary stone disease using dual-source CT. MATERIALS AND METHODS: Forty consecutive patients (mean age 46.6 +/- 16.2 years, range 27-85 years) suspected of having urinary stone disease underwent dual-source CT of the urinary tract. A 3-phasic CT scan protocol consisting of a standard unenhanced scan, a nephrographic, and an excretory phase of contrast enhancement was performed. The nephrographic phase scan was acquired in the dual-energy mode (80 kV/400 mA and 140 kV/95 mA) allowing reconstruction of virtual unenhanced images. Two blinded readers independently compared standard and virtual unenhanced CT for the number, size, and location of urinary stones. Measurements of anteroposterior abdominal diameters were performed to determine abdominal obesity. RESULTS: Standard unenhanced CT revealed 35 uroliths in 18 of the 40 patients (18 of 40; 45%), virtual unenhanced CT demonstrated 26 uroliths in 15 of the 40 patients (15 of 40; 38%) ([kappa] value 0.89). Three false-negative and no false-positive ratings occurred using virtual unenhanced CT, and false-negative ratings solely occurred in obese patients. Sensitivity, specificity, positive predictive, and negative predictive values for virtual unenhanced CT for the diagnosis of urinary stone disease were 83%, 100%, 100%, and 88%, respectively. CONCLUSIONS: Virtual unenhanced CT images reconstructed from contrast-enhanced dual-energy CT allow detection of urinary stones with good sensitivity and excellent specificity, but sensitivity is decreased in abdominal obese patients.

Dual-source computed tomography in patients with acute chest pain: feasibility and image quality.

The aim of this study was to determine the feasibility and image quality of dual-source computed tomography angiography (DSCTA) in patients with acute chest pain for the assessment of the lung, thoracic aorta, and for pulmonary and coronary arteries. Sixty consecutive patients (32 female, 28 male, mean age 58.1+/-16.3 years) with acute chest pain underwent contrast-enhanced electrocardiography-gated DSCTA without prior beta-blocker administration. Vessel attenuation of different thoracic vascular territories was measured, and image quality was semi-quantitatively analyzed by two independent readers. Image quality of the thoracic aorta was diagnostic in all 60 patients, image quality of pulmonary arteries was diagnostic in 59, and image quality of coronary arteries was diagnostic in 58 patients. Pairwise intraindividual comparisons of attenuation values were small and ranged between 1+/-6 HU comparing right and left coronary artery and 56+/-9 HU comparing the pulmonary trunk and left ventricle. Mean attenuation was 291+/-65 HU in the ascending aorta, 334+/-93 HU in the pulmonary trunk, and 285+/-66 HU and 268+/-67 HU in the right and left coronary artery, respectively. DSCTA is feasible and provides diagnostic image quality of the thoracic aorta, pulmonary and coronary arteries in patients with acute chest pain.

Flow and wall shear stress in end-to-side and side-to-side anastomosis of venous coronary artery bypass grafts.

PURPOSE: Coronary artery bypass graft (CABG) surgery represents the standard treatment of advanced coronary artery disease. Two major types of anastomosis exist to connect the graft to the coronary artery, i.e., by using an end-to-side or a side-to-side anastomosis. There is still controversy because of the differences in the patency rates of the two types of anastomosis. The purpose of this paper is to non-invasively quantify hemodynamic parameters, such as mass flow and wall shear stress (WSS), in end-to-side and side-to-side anastomoses of patients with CABG using computational fluid dynamics (CFD). METHODS: One patient with saphenous CABG and end-to-side anastomosis and one patient with saphenous CABG and side-to-side anastomosis underwent 16-detector row computed tomography (CT). Geometric models of coronary arteries and bypasses were reconstructed for CFD analysis. Blood flow was considered pulsatile, laminar, incompressible and Newtonian. Peri-anastomotic mass flow and WSS were quantified and flow patterns visualized. RESULTS: CFD analysis based on in-vivo CT coronary angiography data was feasible in both patients. For both types of CABG, flow patterns were characterized by a retrograde flow into the native coronary artery. WSS variations were found in both anastomoses types, with highest WSS values at the heel and lowest WSS values at the floor of the end-to-side anastomosis. In contrast, the highest WSS values of the side-to-side anastomosis configuration were found in stenotic vessel segments and not in the close vicinity of the anastomosis. Flow stagnation zones were found in end-to-side but not in side-to-side anastomosis, the latter also demonstrating a smoother stream division throughout the cardiac cycle. CONCLUSION: CFD analysis of venous CABG based on in-vivo CT datasets in patients was feasible producing qualitative and quantitative information on mass flow and WSS. Differences were found between the two types of anastomosis warranting further systematic application of the presented methodology on multiple patient datasets.

MR imaging of cartilage in cadaveric wrists: comparison between imaging at 1.5 and 3.0 T and gross pathologic inspection.

PURPOSE: To evaluate prospectively the diagnostic accuracy of magnetic resonance (MR) imaging in the identification of cartilage abnormalities at 3.0 and 1.5 T in cadaveric wrists, with gross pathologic findings as the standard of reference. MATERIALS AND METHODS: The study was approved by the hospital review board, and informed consent for scientific use of body parts had been provided by the subjects. Ten cadaveric wrists from nine subjects were evaluated (seven left wrists, three right; five women, four men; age range, 46-99 years; mean age, 80 years). All wrists were examined with MR imaging in a 1.5-T unit and a 3.0-T unit, with the same imaging protocol used with both systems. Imaging protocol included intermediate-weighted fast spin-echo sequences and three-dimensional gradient-recalled-echo sequences. Cartilage surfaces of the proximal and distal carpal row, including the scaphotrapeziotrapezoidal joint, were analyzed in blinded fashion by two musculoskeletal radiologists working independently and then in consensus. Open inspection of the wrists was used as the standard of reference. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. The McNemar test was used to assess differences in diagnostic assessment. Weighted kappa values were calculated for interobserver agreement. RESULTS: One hundred seventy cartilage surfaces were graded. The sensitivity and specificity for cartilage lesions were 43%-52% and 82%-89%, respectively, at 1.5 T and 48%-52% and 82% at 3.0 T. Differences in assessment did not reach statistical significance (P > .99). Highest sensitivities were found in the proximal carpal row (67%-71%); lowest sensitivities were found in the distal carpal row (14%-24%). Interobserver agreement was higher for imaging at 3.0 T (kappa = 0.634) than at 1.5 T (kappa = 0.267). CONCLUSION: The performance of MR imaging for the detection of articular cartilage abnormalities in the wrist depends on anatomic location. Interobserver agreement is higher for imaging at 3.0 than at 1.5 T, but diagnostic performances were not significantly different (P > .99) at either field strength.

Visualization of congenital thoracic vascular anomalies using multi-detector row computed tomography and two- and three-dimensional post-processing.

Anomalies of the vascular system are caused by false embryogenesis and are therefore present from birth. Single-detector row spiral computed tomography angiography (CTA) and multi-detector row computed tomography angiography (MDCTA) have gained increasing importance in the non-invasive assessment of vascular pathologies and replace conventional angiography in many cases. High-resolution volumetric datasets that are acquired during a single breath-hold give the possibility of two- (2D) and three-dimensional (3D)-post-processing. Due to post-processing, even complex vascular malformations are visualized in an understandable way. Furthermore, CTA, in contrast to conventional angiography, depicts not only the vascular structures but also allows assessment of the surrounding anatomical structures. We present cases of rare congenital anomalies of the thoracic vessels using MDCT with special respect to 2D- and 3D-post-processing.

In-vivo flow simulation in coronary arteries based on computed tomography datasets: feasibility and initial results.

The purpose of this paper was to non-invasively assess hemodynamic parameters such as mass flow, wall shear stress (WSS), and wall pressure with computational fluid dynamics (CFD) in coronary arteries using patient-specific data from computed tomography (CT) angiography. Five patients (two without atherosclerosis, three with atherosclerosis) underwent retrospectively electrocardiogram (ECG) gated 16-detector row CT using ECG-pulsing and geometric models of coronary arteries were reconstructed for CFD analysis. Blood flow was considered laminar, incompressible, Newtonian, and pulsatile. The mass flow, WSS, and wall pressure were quantified and flow patterns were visualized. The wall pressure continuously decreased towards distal segments and showed pressure drops in stenotic segments. In coronary segments without atherosclerotic wall changes, WSS remained low, even during phases of high flow velocity, whereas in atherosclerotic vessels, the WSS was elevated already at low flow velocities. Stenoses and post-stenotic dilatations led to flow acceleration and rapid deceleration, respectively, including a distortion of flow. Areas of high WSS and high flow velocities were found adjacent to plaques, with values correlating with the degree of stenosis. CFD provided detailed mass flow measurements. CFD analysis is feasible in normal and atherosclerotic coronary arteries and provides the rationale for further investigation of the links between hemodynamic parameters and the significance of coronary stenoses.