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Purpose To determine the impact of patient age on the cost-effectiveness of endovascular therapy (EVT) in addition to standard care (SC) in large-vessel-occlusion stroke for patients aged 50 to 100 years in the United States. Materials and Methods A decision-analytic Markov model was used to estimate direct and indirect lifetime costs and quality-adjusted life years (QALYs). Age-dependent input parameters were obtained from the literature. Deterministic and probabilistic sensitivity analysis for age at index stroke were used. The willingness-to-pay (WTP) was set to thresholds of $50 000, $100 000, and $150 000 per QALY. The study applied a U.S. setting for health care and societal perspectives. Incremental costs and effectiveness were derived from deterministic and probabilistic sensitivity analysis. Acceptability rates at different WTP thresholds were determined. Results EVT+SC was the dominant strategy in patients aged 50 to 79 years. The highest incremental effectiveness (2.61 QALYs) and cost-savings (health care perspective, $99 555; societal perspective, $146 385) were obtained in 50-year-old patients. In octogenarians (80-89 years), EVT+SC led to incremental QALYs at incremental costs with acceptability rates of more than 85%, more than 99%, and more than 99% at a WTP of $50 000, $100 000, and $150 000 per QALY, respectively. In nonagenarians (90-99 years), acceptability rates at a WTP of $50 000 per QALY dropped but stayed higher than 85% and higher than 95% at thresholds of $100 000 and $150 000 per QALY. Conclusion Using contemporary willingness-to-pay thresholds in the United States, endovascular therapy in addition to standard care reduces lifetime costs for patients up to 79 years of age and is cost-effective for patients aged 80 to 100 years.

Purpose To prospectively evaluate the perfusion patterns at quantitative dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging of transient bone marrow edema syndrome (TBMES) and avascular osteonecrosis. Materials and Methods Institutional review board approval and written informed consent were obtained. Thirty-two patients (21 men, 11 women; mean age, 48 years; 26 hips, 10 knees) underwent conventional MR imaging and a dynamic contrast-enhanced three-dimensional spoiled gradient-echo sequence at 3 T. Parameter maps for mean transit time (MTT) and plasma flow (PF) were evaluated qualitatively and quantitatively. Differences in perfusion patterns were analyzed by using the Fisher exact test. Regions of interest were drawn in areas of high PF and long MTT on each parametric map. Mean, median, standard deviation, minimum, and maximum values were determined. TBMES and osteonecrosis were compared statistically by using the Mann-Whitney U and Wilcoxon signed-rank tests, with a P value of less than .05 considered indicative of a significant difference. Results Nineteen joints with TBMES and 17 joints with osteonecrosis were evaluated. TBMES joints showed a subchondral elongated area of high PF and low MTT that was surrounded by an area of long MTT and low PF. Osteonecrosis joints showed a subchondral area with low or no detectable PF and MTT adjacent to the joint surface, which was surrounded by a rim of high PF and intermediate MTT. Patterns for TBMES and osteonecrosis did not overlap. A significant difference (P.001) in PF in the immediate subchondral area was found between TBMES and osteonecrosis; in joints with osteonecrosis, this was comparable to background noise, and therefore, could not be quantified. In the circumscribed rim of high PF and intermediate MTT, which was only found in joints with osteonecrosis, mean ± standard deviation PF was 18.9 mL/100 mL per minute ± 11.0 and mean MTT was 213.3 seconds ± 56.8. No significant difference between TBMES and osteonecrosis was found for MTT (P = .09) and PF (P = .75) in the surrounding area. Conclusion Parameter maps derived at dynamic contrast-enhanced MR imaging with high temporal resolution can allow differentiation of osteonecrosis from TBMES in hip and knee joints.

To test the hypothesis that the joint distribution of x-ray transmission and dark-field signals obtained with a compact cone-beam preclinical scanner with a polychromatic source can be used to diagnose pulmonary emphysema in ex vivo murine lungs.The animal care committee approved this study. Three excised murine lungs with pulmonary emphysema and three excised murine control lungs were imaged ex vivo by using a grating-based micro-computed tomographic (CT) scanner. To evaluate the diagnostic value, the natural logarithm of relative transmission and the natural logarithm of dark-field scatter signal were plotted on a per-pixel basis on a scatterplot. Probability density function was fit to the joint distribution by using principle component analysis. An emphysema map was calculated based on the fitted probability density function.The two-dimensional scatterplot showed a characteristic difference between control and emphysematous lungs. Control lungs had lower average median logarithmic transmission (-0.29 vs -0.18, P = .1) and lower average dark-field signal (-0.54 vs -0.37, P = .1) than emphysematous lungs. The angle to the vertical axis of the fitted regions also varied significantly (7.8° for control lungs vs 15.9° for emphysematous lungs). The calculated emphysema distribution map showed good agreement with histologic findings.X-ray dark-field scatter images of murine lungs obtained with a preclinical scanner can be used in the diagnosis of pulmonary emphysema.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122413/-/DC1.

To assess the use of diffusion-tensor (DT) imaging of articular cartilage to detect and grade early cartilage damage in human specimens with early signs of cartilage damage.This study was approved by the institutional review board. Forty-three cartilage-on-bone samples drilled from 21 human patellae were examined with 17.6-T magnetic resonance (MR) imaging and a diffusion-weighted spin-echo sequence (spatial resolution, 50 × 100 × 800 μm). Subsequently, samples underwent histologic analysis with safranin O staining. Cartilage damage on safranin O histologic slides was quantified with Osteoarthritis Research Society International (OARSI) grades; grades ranged from 0 (healthy) to 6 (bone remodeling). Maps of longitudinal diffusivity (λ(l)), transverse diffusivity (λ(t)), mean diffusivity (MD), and fractional anisotropy (FA) were calculated. Cartilage was segmented, and region of interest (ROI) analysis was performed and compared with histologic findings. Significant differences in MR parameters between the OARSI groups were assessed with the Tukey test. The value of DT imaging in the diagnosis and grading of cartilage damage was assessed with logistic regression analysis.Samples had OARSI grades of 0 (n = 14), 1 (n = 11), 2 (n = 12), 3 (n = 4), and 4 (n = 2). Samples with an OARSI grade greater than 0 had significantly increased λ(l), λ(t), and MD (7%-25% increase) in the superficial cartilage growing deeper into cartilage with increasing OARSI grade. Samples with an OARSI grade greater than 0 showed significantly decreased FA in the deep cartilage (-25% to -35% decrease), suggesting that changes in the collagen architecture may occur early in cartilage degradation. DTI showed excellent performance in the detection of cartilage damage (accuracy, 0.95; 41 of 43 samples) and good performance in the grading of cartilage damage (accuracy, 0.74; 32 of 43 samples).DT imaging of articular cartilage can enable physicians to detect and grade early cartilage damage.

To compare objective and subjective image quality parameters of three image reconstruction algorithms of different generations at routine multidetector computed tomographic (CT) examinations of the abdomen.This institutional review board-approved study included 22 consecutive patients (mean age, 56.1 years ± 15.8 [standard deviation]; mean weight, 79.1 kg ± 14.8) who underwent routine CT examinations of the abdomen. A low-contrast phantom was used for objective quality control. Raw data sets were reconstructed by using filtered back projection (FPB), adaptive statistical iterative reconstruction (ASIR), and a model-based iterative reconstruction (MBIR). Radiologists used a semiquantitative scale (-3 to +3) to rate subjective image quality and artifacts, comparing both FBP and MBIR images with ASIR images. The Wilcoxon test and the intraclass correlation coefficient were used to evaluate the data. Measurements of objective noise and CT numbers of soft tissue structures were compared with analysis of variance.The phantom study revealed an improved detectability of low-contrast targets for MBIR compared with ASIR or FBP. Subjective ratings showed higher image quality for MBIR, with better resolution (median value, 2; range, 1 to 3), lower noise (2; range, 1 to 3), and finer contours (2; range, 1 to 2) compared with ASIR (all P.001). FBP performed inferiorly (0, range, -2 to 0]; -1 [range, -3 to 0]; 0 [range, -1 to 0], respectively; all, P.001). Mean interobserver correlation was 0.9 for image perception and 0.7 for artifacts. Objective noise for FBP was 14%-68% higher and for MBIR was 18%-47% lower than that for ASIR (P.001).The MBIR algorithm considerably improved objective and subjective image quality parameters of routine abdominal multidetector CT images compared with those of ASIR and FBP.

To prospectively compare findings of magnetic resonance (MR) lymphangiography with those of lymphoscintigraphy, evaluate the pattern and delay of lymphatic drainage, compare typical findings, and investigate discrepancies between the techniques.This prospective study was performed according to the Declaration of Helsinki and was approved by the local ethics committee. Thirty consecutive patients with uni- or bilateral lymphedema and lymph vessel transplants of the lower extremities were examined with 3.0-T fat-saturated three-dimensional gradient-echo MR after gadopentetate dimeglumine injection. Results of all examinations were correlated with corresponding results of lymphoscintigraphy examinations. Results of both techniques were separately reviewed in consensus by a radiologist and a nuclear physician, who rated delay and pattern of drainage, number of enhancing levels, and quality of conspicuity of the depiction of lymph nodes and lymph vessels. Sensitivity and specificity were calculated by using combined results of both techniques and clinical presentation findings as reference standard. Correlation was calculated with weighted k coefficients.Weak lymphatic drainage at lymphoscintigraphy correlated with lymphangiectasia at MR lymphangiography (13 of 33 affected extremities). Lymph vessels were clearly visualized with MR lymphangiography (five of 24 affected extremities), while they were not detectable with lymphoscintigraphy. Depiction of inguinal lymph nodes was clearer with lymphoscintigraphy (five of 60 extremities). Correlation of both techniques was excellent for delay (κ=0.93) and pattern (κ=0.84) of drainage, good for depiction of lymph nodes (κ=0.67) and number of enhancing levels (κ=0.77), and moderate for depiction of lymph vessels (κ=0.50). Sensitivity and specificity for delay and pattern of drainage were concordant, whereas MR lymphangiography showed a higher sensitivity for lymph vessel abnormalities (100% vs 79%) and lower specificity for lymph node abnormalities (78% vs 100%).Imaging findings of MR lymphangiography and lymphoscintigraphy show a clear concordance. With lymphoscintigraphy, better visualization of inguinal lymph nodes was achieved, whereas with MR lymphangiography, better depiction of lymph vessels and morphologic features of lymph vessel abnormalities were achieved.

To evaluate the feasibility of quantifying hepatic perfusion and function by using dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging with the hepatobiliary contrast agent gadoxetic acid and a dual-inlet two-compartment uptake model.The study was approved by the local institutional review board, and written informed consent was obtained from all patients. Data were acquired between October 2008 and November 2009 in 24 patients with hepatic metastases from neuroendocrine tumors (13 men, 11 women; mean age, 59.8 years). DCE MR imaging was performed at 3.0 T with a standard dose of gadoxetic acid and a three-dimensional sequence, with 48 sections of data acquired every 2.2 seconds for 5 minutes. For each patient, a plasma flow map was calculated by means of deconvolution and the model was fitted to six region-of-interest curves. Results were evaluated with goodness-of-fit analysis and, in normal-appearing liver tissue, by comparing perfusion parameters with those reported in the literature. Interobserver effects in the selection of arterial and venous input functions were assessed.With an arterial delay parameter, the model provided a good fit to all data. Values for arterial and venous plasma flow and extracellular volume in normal-appearing liver tissue were comparable to those in the literature. The mean intracellular uptake rate is 3.4/100/min with a standard deviation of 1.9/100/min The model also provided a good fit in all tumor data, producing high arterial flow fraction (87%) and lower uptake (1.7/100/min) . Bias due to observer-dependent differences in the selection of the input functions was negligible.The analysis of dynamic gadoxetic acid-enhanced MR images with the dual-inlet two-compartment uptake model presents a new and practical approach for measuring arterial and venous perfusion and hepatic function in a single acquisition.

To assess the feasibility and diagnostic performance of time-resolved computed tomographic (CT) angiography in the detection and classification of endoleaks after endovascular aortic aneurysm repair (EVAR) in high-risk patients.The study was approved by our ethics committee. Written informed consent was obtained from all participating patients. Fifty-four patients (42 male and 12 female patients; mean age, 70.9 years ± 9.3 [standard deviation]) with either thoracic (n = 8) or abdominal (n = 46) aortic aneurysms treated with a stent-graft were prospectively included. The patients were examined with a time-resolved CT angiographic protocol consisting of 12 low-dose phases (80 kVp; 120 mAs [effective]; scan range, 27 cm), with 60 mL of iomeprol. Patients with abdominal aneurysm repair also underwent contrast material-enhanced (CE) ultrasonography (US). The time delay between contrast enhancement within the stent lumen and the endoleak was measured. Effective radiation dose was calculated from the scanner protocols. Measures of diagnostic performance for the detection of endoleaks were calculated for time-resolved CT angiography, with CE US serving as the reference standard.All time-resolved CT angiographic data sets were diagnostic. Mean effective radiation dose was 14.6 mSv. Four thoracic and 19 abdominal endoleaks were identified by using time-resolved CT angiography. Seventeen of 19 abdominal endoleaks were confirmed with CE US. This rate resulted in a sensitivity of 94%, a specificity of 93%, a positive predictive value of 89%, and a negative predictive value of 96% for time-resolved CT angiography after abdominal EVAR. Type I endoleaks showed significantly earlier mean peak contrast enhancement (0.28 second ± 0.83) compared with that for type II endoleaks (9.17 seconds ± 3.59, P.0001).Time-resolved CT angiography with 12 low-dose phases is feasible for patients after thoracic and abdominal EVAR. The protocol approximates the radiation dose of standard triphasic protocols. Its dynamic information differentiates types of endoleaks and shows high diagnostic performance.

To evaluate whether patients with Alzheimer disease (AD) have altered activation compared with age-matched healthy control (HC) subjects during a task that typically recruits the dorsal visual pathway.The study was performed in accordance with the Declaration of Helsinki, with institutional ethics committee approval, and all subjects provided written informed consent. Two tasks were performed to investigate neural function: face matching and location matching. Twelve patients with mild AD and 14 age-matched HC subjects were included. Brain activation was measured by using functional magnetic resonance imaging. Group statistical analyses were based on a mixed-effects model corrected for multiple comparisons.Task performance was not statistically different between the two groups, and within groups there were no differences in task performance. In the HC group, the visual perception tasks selectively activated the visual pathways. Conversely in the AD group, there was no selective activation during performance of these same tasks. Along the dorsal visual pathway, the AD group recruited additional regions, primarily in the parietal and frontal lobes, for the location-matching task. There were no differences in activation between groups during the face-matching task.The increased activation in the AD group may represent a compensatory mechanism for decreased processing effectiveness in early visual areas of patients with AD. The findings support the idea that the dorsal visual pathway is more susceptible to putative AD-related neuropathologic changes than is the ventral visual pathway.

To prospectively compare three-dimensional (3D) contrast material-enhanced abdominal magnetic resonance (MR) angiography at 1.5 and 3.0 T intraindividually in healthy volunteers.After institutional review board approval and informed consent were obtained, 15 healthy male volunteers (age range, 24-41 years) underwent one abdominal 3D contrast-enhanced MR angiographic examination each at 1.5 and 3.0 T in random order. Fast 3D gradient-echo sequence with parallel imaging acceleration factor of three was used for MR angiography; acquired spatial resolutions were 1x0.8x1 mm3 (imaging time, 19 seconds) at 1.5 T and 0.9x0.8x0.9 mm3 (imaging time, 18 seconds) at 3.0 T. With the latter, volume of the 3D slab was 8% larger. At 1.5 T, 20-mL bolus of gadobenate dimeglumine was delivered at 2 mL/sec; at 3.0 T, 15-mL bolus was delivered at 2.5 mL/sec. Two blinded radiologists rated image quality of aorta and proximal renal arteries in consensus with five-point scale (4=very good, 0=nondiagnostic) according to sequence and in direct intraindividual comparison. Visibility of proximal and segmental renal arteries was rated with three-point scale (3=completely visible, 1=nonvisible). Signal-to-noise ratio (SNR) was determined with phantoms. For statistical analysis of the SNRs, t tests were used.All MR angiographic measurements were diagnostic. Median score for image quality at both field strengths was 4. Depiction of proximal renal arteries was rated 3 at both field strengths. The visibility of the distal renal arteries was better at 3.0 T (median score, 3) than at 1.5 T (median score, 2). With direct comparison, 3.0-T MR angiography was better in 14 of 15 cases; no field strength was preferred in the other case. Mean SNR was significantly (P.001) higher at 3.0 T (17.8+/-0.09 [standard deviation]) than at 1.5 T (11.9+/-0.10).MR angiography at 3.0 T provided better vessel visibility and SNR than did that at 1.5 T, although voxel size and imaging time were reduced.

To prospectively determine regional differences in fiber tract integrity between elderly patients with Alzheimer disease (AD), those with mild cognitive impairment (MCI), and healthy elderly subjects by using diffusion-tensor imaging with parallel imaging techniques and a new eight-element receiving coil.Institutional review board approval and informed consent were obtained. Fifteen patients with AD (seven men, eight women; mean age; 68.8 years), 16 patients with MCI (nine men, seven women; mean age, 68.9 years) and 19 healthy control subjects (eight men, 11 women; mean age, 63.9 years) underwent diffusion-tensor imaging performed with a 1.5-T magnetic resonance system. An echo-planar imaging diffusion sequence was used with an integrated parallel acquisition technique (PAT) and an eight-element head coil. The mean apparent diffusion coefficient (ADC), fractional anisotropy (FA), and relative anisotropy (RA) values of several white matter (WM) regions were determined. The Kruskal-Wallis test was used initially to test for overall equality of median values in each data group. Single posttest comparisons were performed with the Mann-Whitney U test, with an overall statistical significance level of .05.FA and RA values were significantly (P.05) decreased, whereas ADC values in the splenium of the corpus callosum were higher in patients with AD than in patients with MCI. Evidence of higher ADC values in the WM of the temporal lobe was observed in patients with AD compared with the ADC values in patients with MCI and in control subjects. ADC values in the parietal WM were significantly (P.05) elevated in patients with MCI compared with those in control subjects. The images obtained with integrated PAT showed fewer susceptibility artifacts and were less distorted than images acquired without parallel imaging techniques.Reduced FA and RA values in patients with AD suggest that diffusion-tensor imaging of the brain can be used to confirm clinical manifestation of AD but is less applicable in the detection of MCI.

The purpose of this study was to prospectively evaluate the diagnostic accuracy of reader detection of 75% or greater stenosis at high-spatial-resolution multistation magnetic resonance (MR) angiography performed with matrix coils and a blood pool contrast agent. Ten healthy volunteers and 10 patients were examined. All participants provided informed consent to participate in this institutional review board-approved study. For contrast agent-enhanced multistation MR angiography, an albumin-binding gadolinium chelate, gadofosveset trisodium, was used. Imaging was performed during the first-pass and steady-state phases of the contrast agent. Vessel conspicuity on the first-pass MR angiograms obtained in both volunteers and patients was rated as excellent for 93% of vessels. At steady-state imaging, vessel conspicuity was rated as excellent or good for 89% of vessels. Gadofosveset trisodium-enhanced MR angiography yielded sensitivities of 100% and 97% and specificities of 96% and 97% for detection of significant disease in the carotid and lower extremity arteries, respectively.

To prospectively assess feasibility of renal magnetic resonance (MR) perfusion measurement method based on turbo fast low-angle shot sequences for grading effect of renal artery stenosis (RAS) on parenchymal perfusion.Institutional review board approved this study, and patients gave written consent. Seventy-three patients (34 male, 39 female; age range, 17-84 years) who were clinically suspected of having RAS underwent contrast material-enhanced (gadodiamide) saturation-recovery turbo fast low-angle shot imaging for measurement of renal perfusion and high-spatial-resolution MR angiography for RAS detection and grading. Degree of stenosis was evaluated as high grade (/=75% stenosis), low to intermediate grade (0% to75% stenosis), or absent. High temporal resolution of the turbo fast low-angle shot sequence allowed acquisition of an exact first-pass tracing of the contrast agent bolus from which a signal intensity (SI)-time curve was derived. On the basis of this curve, mean transit time (MTT) of the contrast agent bolus, maximal upslope (MUS) of the curve, maximum SI, and time to SI peak (TTP) were calculated with a gamma variate fit. Wilcoxon rank sum test, Pearson product moment correlation, and paired t test were used for statistical analysis.Twenty-four renal arteries had high-grade RAS, 12 renal arteries had low- to intermediate-grade RAS, and 104 renal arteries had no RAS. Significant differences between patients without stenoses or with low- to intermediate-grade stenoses and patients with high-grade stenoses were found for MTT, MUS, and TTP (P.001). Perfusion parameters were correlated with patients' serum creatinine levels, and significant correlations were found for MTT (r = 0.41), MUS (r = 0.48), and TTP (r = 0.4), with P.001.MR perfusion parameters can be used to assess effect of RAS on parenchymal perfusion. Perfusion measurements reflect renal function as measured with serum creatinine levels.

To determine prospectively the accuracy of a magnetic resonance (MR) perfusion imaging and MR angiography protocol for differentiation of chronic thromboembolic pulmonary arterial hypertension (CTEPH) and primary pulmonary hypertension (PPH) by using parallel acquisition techniques.The study was approved by the institution's internal review board, and all patients gave written consent prior to participation. A total of 29 patients (16 women; mean age, 54 years +/- 17 [+/- standard deviation]; 13 men; mean age, 57 years +/- 15) with known pulmonary hypertension were examined with a 1.5-T MR imager. MR perfusion imaging (temporal resolution, 1.1 seconds per phase) and MR angiography (matrix, 512; voxel size, 1.0 x 0.7 x 1.6 mm) were performed with parallel acquisition techniques. Dynamic perfusion images and reformatted three-dimensional MR angiograms were analyzed for occlusive and nonocclusive changes of the pulmonary arteries, including perfusion defects, caliber irregularities, and intravascular thrombi. MR perfusion imaging results were compared with those of radionuclide perfusion scintigraphy, and MR angiography results were compared with those of digital subtraction angiography (DSA) and/or contrast material-enhanced multi-detector row computed tomography (CT). Sensitivity, specificity, and diagnostic accuracy of MR perfusion imaging and MR angiography were calculated. Receiver operator characteristic analyses were performed to compare the diagnostic value of MR angiography, MR perfusion imaging, and both modalities combined. For MR angiography and MR perfusion imaging, kappa values were used to assess interobserver agreement.A correct diagnosis was made in 26 (90%) of 29 patients by using this comprehensive MR imaging protocol. Results of MR perfusion imaging demonstrated 79% agreement (ie, identical diagnosis on a per-patient basis) with those of perfusion scintigraphy, and results of MR angiography demonstrated 86% agreement with those of DSA and/or CT angiography. Interobserver agreement was good for both MR perfusion imaging and MR angiography (kappa = 0.63 and 0.70, respectively).The combination of fast MR perfusion imaging and high-spatial-resolution MR angiography with parallel acquisition techniques enables the differentiation of PPH from CTEPH with high accuracy.

The purpose of this study was to integrate parallel acquisition techniques into a comprehensive whole-body cardiovascular screening protocol to image all relevant organ systems without compromising spatial or temporal resolution. The study was approved by the institutional review board, and oral and written informed consent was obtained from each subject. Fifty subjects underwent whole-body magnetic resonance imaging that included imaging of heart, blood vessels, brain, lungs, and abdominal organs with a standard eight-channel imager. Image quality and pathologic findings were evaluated by two readers. The same protocol was then implemented with a new 32-channel whole-body imager. Depiction of 1476 (73.2%) of 2016 vessel segments was rated as good to excellent, and that of 1744 (86.5%), as without venous overlay. Interobserver agreement was good in evaluation of image quality and excellent in evaluation of pathologic findings. Acquisition time was reduced significantly (P.05) with use of the whole-body imager and parallel acquisition techniques, which provided high-quality fast cardiovascular imaging.

The purpose of this study was to develop a spike-related functional magnetic resonance (MR) imaging method to detect epileptic brain activity. Correlations between simultaneous spike-related functional MR imaging and electroencephalographic (EEG) recordings were performed in 10 patients with focal epilepsy. Postprocessing techniques were implemented to eliminate contamination of the EEG recording from ballistocardiography and the echo-planar MR imaging sequence. A diagnostic EEG recording was achieved during functional MR imaging. Spike location correlated with the site of blood oxygen level-dependent signal increase. Spike-related functional MR imaging is a promising technique for detecting focal epileptic brain activity.

(a) To determine the accuracy of multi-detector row computed tomography (CT) in the measurement of the calcium concentration in a cardiac CT calibration phantom and (b) to assess the correlation of a traditional 3-mm section width CT coronary screening protocol and a 1.25-mm section width CT angiography imaging protocol in the quantification of the absolute mass of coronary calcium in patients who underwent both coronary screening and CT angiography with a multi-detector row CT scanner.A heart phantom containing calcified cylinders was scanned to determine calibration factors and absolute calcium mass. In 50 patients, the variability (value 1 - value 2/mean value 1 - value 2), limit of agreement (+/-2SD value 1 - value 2), and systematic error (mean value 1 - value 2) of the total amount of coronary calcium calculated at traditional 3-mm section width CT and at 1.25-mm section width CT angiography were determined.The correlation coefficient between the 3-mm section width, nonenhanced protocol and the 1.25-mm section width CT angiography protocol was very high (r = 0.977) and the mean variability was low (19.7%) for the absolute mass. There was a systematic error of -6.7 mg and a limit of agreement between 45.0 mg and -58.5 mg.Use of the mass quantification algorithm in combination with a calibration phantom allows accurate quantification of coronary calcium. Measurements of calcium mass obtained at 1.25-mm section width CT angiography have the best agreement with those obtained at the traditional 3-mm section width imaging protocol.

To evaluate the potential of phase-contrast computed tomography (CT) for atherosclerotic plaque imaging in human carotid arteries in an experimental ex vivo study.The study was approved by the institutional review board, and informed consent was obtained from the patients' relatives. Seven postmortem human carotid artery specimens were imaged at a laboratory setup by using a conventional x-ray tube and grating interferometer. After histologic processing, phase-contrast imaging and histopathologic data were matched. Characteristics of the necrotic core (NC) covered by a fibrous cap (FC), intraplaque hemorrhage (IPH), and calcifications (CAs) were established, and sensitivity, specificity, and accuracy of phase-contrast CT for plaque detection and the potential for accurate quantification were assessed. The Cohen κ and Pearson correlation coefficient R were used to determine the agreement between phase-contrast imaging and histopathologic findings for plaque characterization and correlation of quantitative plaque measurements, respectively. A difference with a P value of less than .05 was considered significant.Characteristic criteria were found in all analyzed plaque components. Applying these criteria, phase-contrast CT had a good sensitivity for the detection of the FC and NC, IPH, and CAs (all,80%) and excellent specificity and accuracy (all,90%), with good interreader agreement (κ ≥ 0.72, P.0001). There were excellent correlations for quantitative measurements of FC, NC, and CAs between phase-contrast imaging and histopathologic findings (R ≥ 0.92). Interreader reproducibility was excellent, with an intraclass correlation coefficient of 0.98 or higher for all measurements.The results of this study indicate that ex vivo phase-contrast CT can help identify and quantify atherosclerotic plaque components, with excellent correlation to histopathologic findings. Although not yet applicable in vivo, phase-contrast CT may become a valuable tool to monitor atherosclerotic disease process noninvasively.

To evaluate the effectiveness of electrocardiographically (ECG)-gated retrospective image reconstruction for multi-detector row computed tomographic (CT) coronary angiography in reducing cardiac motion artifacts and to evaluate the influence of heart rate on cardiac image quality.Sixty-five patients with different heart rates underwent coronary CT angiography. Raw helical CT data and ECG tracings were combined to retrospectively reconstruct at the defined consecutive z position with a temporal resolution of 250 msec per section. The starting points of the reconstruction were chosen between 30% and 80% of the R-R intervals. The relationships between heart rate, trigger delay, and image quality were analyzed.Optimal image quality was achieved with a 50% trigger delay for the right coronary artery and 60% for the left circumflex coronary artery. Optimal image quality for the left anterior descending coronary artery was equally obtained at 50% and 60% triggering. A significant negative correlation was observed between heart rate and image quality (P.05). The best image quality was achieved when the heart rate was less than 74.5 beats per minute.To achieve high image quality, the heart rate should be sufficiently slow. Selection of appropriate trigger delays and a decreasing heart rate are effective to reduce cardiac motion artifacts.

To evaluate diffuse, reactive bone marrow changes in unaffected vertebrae on magnetic resonance (MR) images in patients with proved infectious spondylitis.Percentage signal intensity increase of the unaffected bone marrow on contrast material-enhanced MR images (percentage enhancement) was calculated retrospectively in 22 cases of infectious spondylitis and 86 cases without bone marrow disease. Multiple regression analysis and Student t test statistics were performed.Multiple regression analysis showed a significant influence of age and the presence of spondylitis on the values of percentage enhancement (P:.001). For those aged 35 years or younger, the mean percentage enhancement was 43.2% +/- 4.0 for patients with infectious spondylitis (n = 3) and was 26.4% +/- 8.6 for the control group (n = 23). For those older than 35 years, the mean percentage enhancement was 28.2% +/- 12.2 for patients with infectious spondylitis (n = 19) and 17.5% +/- 7.9 (P:.001) for the control group (n = 63). Six (27%) of 22 patients with infectious spondylitis showed abnormal percentage enhancement values in unaffected bone marrow when the upper limit of the normal value was 2 SDs above the mean of the control group.On MR images, reactive bone marrow changes can be found in unaffected vertebrae in patients with infectious spondylitis. The signal intensity changes and increased percentage enhancement associated with this disease are similar to those of myeloproliferative and diffuse neoplastic disorders and bone marrow stimulation in hemolytic anemia.

The authors introduce a method for cardiac investigations by using electrocardiographically gated spiral scanning with a four-section computed tomographic system. Three-dimensional images were reconstructed by means of a 250-msec temporal resolution and continuous volume coverage by using a dedicated multisection cardiac volume reconstruction algorithm. Motion-free thin-section volume images were acquired with thin sections and overlapping image increments within a single breath hold. Data segment shifts in time allowed for multiphase imaging.

To determine the value of magnetic resonance (MR) sialography for the diagnosis of sialolithiasis by comparing results prospectively with those of ultrasonography (US) and digital sialography.MR sialography was prospectively performed with T2-weighted three-dimensional (3D) constructive interference in steady-state (CISS) and rapid acquisition with relaxation-enhancement (RARE) sequences in 24 patients suspected of having sialolithiasis. Evoked salivation was used as contrast material. T1-weighted spin-echo and T2-weighted turbo spin-echo MR imaging also were performed. The results were then compared with those of US and digital sialography, with the latter as standard of reference.The 3D CISS images were significantly (P:.05) superior to RARE images for demonstrating the submandibular ductal system, followed by T2-weighted turbo spin-echo images (P:.01) and T1-weighted spin-echo images (P:.001). The sensitivity and specificity were 100% and 80%, respectively, for CISS MR sialography and 80% and 100%, respectively, for RARE MR imaging. The sensitivity and specificity of US were both 80%.MR sialography with evoked salivation is noninvasive and allows delineation of the submandibular ductal system and detection of sialoliths with accuracy that is similar to that of digital sialography and superior to that of US.

To determine the value of non-electrocardiographically triggered contrast material-enhanced magnetic resonance (MR) angiography in assessing the patency of venous and internal thoracic artery (ITA) grafts after coronary bypass surgery.Twenty-seven patients with 76 coronary bypass grafts (48 venous, 28 ITA) were examined 26.5 months +/- 5.8 after surgery with MR angiography and conventional angiography. MR angiography was performed with a three-dimensional gradient-echo sequence after automated injection of contrast material; contrast agent administration was based on measurement of the individual transit time of the agent. Results of MR angiography were interpreted by two independent observers and compared with results of conventional angiography.The independent interpretations of the MR angiograms agreed with the results of conventional angiography in 96% and 91% of the grafts. After a final consensus reading, sensitivity was 95% for all grafts, 94% for venous grafts, and 96% for ITA grafts. Specificity was 85% for venous grafts and 67% for ITA grafts. Positive predictive value was 95% for all grafts, 94% for venous grafts, and 96% for ITA grafts.Non-electrocardiographically triggered contrast-enhanced MR angiography allows reliable assessment of the patency of venous and arterial coronary bypass grafts.

To investigate technical feasibility, test-retest reproducibility, and the ability to differentiate healthy subjects from subjects with osteoarthritis (OA) with diffusion-tensor (DT) imaging parameters and T2 relaxation time.This study was approved by the institutional review board and was HIPAA compliant. All subjects provided written informed consent. DT imaging parameters and T2 (resolution=0.6×0.6×2 mm) of patellar cartilage were measured at 7.0 T in 16 healthy volunteers and 10 patients with OA with subtle inhomogeneous signal intensity but no signs of cartilage erosion at clinical magnetic resonance (MR) imaging. Ten volunteers were imaged twice to determine test-retest reproducibility. After cartilage segmentation, maps of mean apparent diffusion coefficient (ADC), fractional anisotropy (FA), and T2 relaxation time were calculated. Differences for ADC, FA, and T2 between the healthy and OA populations were assessed with nonparametric tests. The ability of each MR imaging parameter to help discriminate healthy subjects from subjects with OA was assessed by using receiver operating characteristic curve analysis.Test-retest reproducibility was better than 10% for mean ADC (8.1%), FA (9.7%), and T2 (5.9%). Mean ADC and FA differed significantly (P.01) between the OA and healthy populations, but T2 did not. For ADC, the optimal threshold to differentiate both populations was 1.2×10(-3) mm2/sec, achieving specificity of 1.0 (16 of 16) and sensitivity of 0.80 (eight of 10). For FA, the optimal threshold was 0.25, yielding specificity of 0.88 (14 of 16) and sensitivity of 0.80 (eight of 10). T2 showed poor differentiation between groups (optimal threshold=22.9 msec, specificity=0.69 [11 of 16], sensitivity=0.60 [six of 10]).In vivo DT imaging of patellar cartilage is feasible, has good test-retest reproducibility, and may be accurate in discriminating healthy subjects from subjects with OA. ADC and FA are two promising biomarkers for early OA.

To determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the detection of hemodynamically significant coronary artery stenosis, as defined with fractional flow reserve (FFR).Institutional review board approval and informed patient consent were obtained before patient enrollment in the study. The study was HIPAA compliant. Subjects who were suspected of having or were known to have coronary artery disease underwent electrocardiographically triggered dynamic stress myocardial perfusion imaging. FFR measurement was performed within all main coronary arteries with a luminal narrowing of 50%-85%. Estimated myocardial blood flow (MBF) was derived from CT images by using a model-based parametric deconvolution method for 16 myocardial segments and was related to hemodynamically significant coronary artery stenosis with an FFR of 0.75 or less in a blinded fashion. Conventional measures of diagnostic accuracy were derived, and discriminatory power analysis was performed by using logistic regression analysis.Of 36 enrolled subjects, 33 (mean age, 68.1 years ± 10 [standard deviation]; 25 [76%] men, eight [24%] women) completed the study protocol. An MBF cut point of 75 mL/100 mL/min provided the highest discriminatory power (C statistic, 0.707; P.001). While the diagnostic accuracy of CT for the detection of anatomically significant coronary artery stenosis (50%) was high, it was low for the detection of hemodynamically significant stenosis (positive predictive value [PPV] per coronary segment, 49%; 95% confidence interval [CI]: 36%, 60%). With use of estimated MBF to reclassify lesions depicted with CT angiography, 30 of 70 (43%) coronary lesions were graded as not hemodynamically significant, which significantly increased PPV to 78% (95% CI: 61%, 89%; P = .02). The presence of a coronary artery stenosis with a corresponding MBF less than 75 mL/100 mL/min had a high risk for hemodynamic significance (odds ratio, 86.9; 95% CI:17.6, 430.4).Dynamic CT-based stress myocardial perfusion imaging may allow detection of hemodynamically significant coronary artery stenosis.

At the 2009 Scientific Assembly and Annual Meeting of the Radiological Society of North America, a special session was devoted to global trends in hybrid imaging. This article expands on the key points of the session, focusing primarily on positron emission tomography/computed tomography. Global trends in hybrid imaging equipment acquisition, usage, and image interpretation practices are reviewed, and emerging requirements for training and clinical privileging are discussed. Also considered are the current benefits of hybrid imaging for patient care and workflow and the potential of hybrid imaging for advancing drug development and personalized medicine.

To qualitatively and quantitatively compare virtual nonenhanced (VNE) data sets derived from dual-energy (DE) computed tomography (CT) with true nonenhanced (TNE) data sets in the same patients and to calculate potential radiation dose reductions for a dual-phase renal multidetector CT compared with a standard triple-phase protocol.This prospective study was approved by the institutional review board; all patients provided written informed consent. Seventy one men (age range, 30-88 years) and 39 women (age range, 22-87 years) underwent preoperative DE CT that included unenhanced, DE nephrographic, and delayed phases. DE CT parameters were 80 and 140 kV, 96 mAs (effective). Collimation was 14 x 1.2 mm. CT numbers were measured in renal parenchyma and tumor, liver, aorta, and psoas muscle. Image noise was measured on TNE and VNE images. Exclusion of relevant anatomy with the 26-cm field of view detector was quantified with a five-point scale (0 = none, 4 =75%). Image quality and noise (1 = none, 5 = severe) and acceptability for VNE and TNE images were rated. Effective radiation doses for DE CT and TNE images were calculated. Differences were tested with a Student t test for paired samples.Mean CT numbers (+/- standard deviation) on TNE and VNE images, respectively, for renal parenchyma were 30.8 HU +/- 4.0 and 31.6 HU +/- 7.1, P = .29; liver, 55.8 HU +/- 8.6 and 57.8 HU +/- 10.1, P = .11; aorta, 42.1 HU +/- 4.1 and 43.0 HU +/- 8.8, P = .16; psoas, 47.3 HU +/- 5.6 and 48.1 HU +/- 9.3 HU, P = .38. No exclusion of the contralateral kidney was seen in 50 patients, less than 25% was seen in 43, 25%-50% was seen in 13, and 50%-75% was seen in four. Mean image noise was 1.71 +/- 0.71 for VNE and 1.22 +/- 0.45 for TNE (P.001); image quality was 1.70 HU +/- 0.72 for VNE and 1.15 HU +/- 0.36 for TNE (P.0001). In all but three patients radiologists accepted VNE images as replacement for TNE images. Mean effective dose for DE CT scans of the abdomen was 5.21 mSv +/- 1.86 and that for nonenhanced scans was 4.97 mSv +/- 1.43. Mean dose reduction by omitting the TNE scan was 35.05%.In patients with renal masses, DE CT can provide high-quality VNE data sets, which are a reasonable approximation of TNE data sets. Integration of DE scanning into a renal mass protocol will lower radiation exposure by 35%.

To evaluate possible radiation dose reduction in the extremities with use of digital radiography and a needle-structured image plate (NIP) by comparing this technique with digital radiography performed with a powder-structured image plate (PIP) and a flat-panel detector (FPD).This study was approved by the local review board. A total of 72 plain radiographs of the feet of six human cadavers were obtained with four surface entrance doses (65, 43, 20, and 10 micro Gy) by using three systems. The reference image of each specimen was obtained with an 85-micro Gy dose and with use of a PIP. Five independent blinded radiologists evaluated the images. The noise level and the depiction of the cortical bone, trabecular bone, and soft tissue were rated and compared with those of the reference image by using a five-point scale. An overall image score was developed for these four criteria by calculating the unweighted mean. The Wilcoxon test was used to assess differences between overall image scores.For each dose, NIP images were significantly superior (P.001), whereas FPD images and PIP images were significantly inferior (P.01). NIP images obtained with 65-, 43-, and 20-micro Gy doses were significantly superior to reference images and to FPD and PIP images obtained with a 65-micro Gy dose. There were no significant differences between reference images and FPD images obtained with 65- and 43-micro Gy doses.Radiation dose can be reduced by 75% in clinical skeletal imaging of peripheral extremities by using NIP, with no significant loss of information. For FPD images, this might be possible with a dose reduction of 50%.

To compare parallel acquisition magnetic resonance (MR) imaging with thin-section helical computed tomography (CT) for depiction of pulmonary abnormalities suggestive of pneumonia in immunocompromised patients.The institutional review board approved this study; prior consent was obtained. Thirty consecutive neutropenic patients (10 women, 20 men; mean age, 51 years +/- 15 [standard deviation]; range, 25-75 years) with fever of unknown origin or clinical signs and symptoms of lung infection were examined with breath-hold single-shot half-Fourier turbo spin-echo MR imaging. To reduce image blurring and increase MR signal in the lungs, the echo time was shortened with generalized autocalibrating partially parallel acquisition (GRAPPA). Patients underwent thoracic CT (four detector rows and 1-mm section thickness [4 x 1 mm]; pitch, 6) as reference standard. Pulmonary abnormalities (ill-defined nodules, ground-glass opacity areas, and consolidation), their location and distribution, and lesion characteristics were analyzed at MR imaging by three readers, blinded to results of CT, in consensus. Frequencies were calculated for each feature; paired Wilcoxon rank sum test was used to examine whether differences between CT and MR imaging features were statistically significant (alpha.05). Bonferroni adjustments were performed. Overall sensitivity, specificity, and positive and negative predictive values were determined.Twenty-two patients had pulmonary abnormalities at CT. In 21 (95%) patients, pneumonia was correctly diagnosed with MR imaging. One false-negative finding occurred in a patient with ill-defined nodules smaller than 1 cm at CT. One false-positive finding with MR imaging was the result of blurring and respiratory artifacts (sensitivity, 95%; specificity, 88%; positive predictive value, 95%; negative predictive value, 88%). There was no significant difference in lesion location and distribution.With parallel imaging (GRAPPA technique) and fast MR imaging, detection of pulmonary abnormalities is almost as good as with CT. MR imaging has a slight disadvantage in its lower capability to assist in characterization of specific internal features, such as cavitations.

To prospectively determine if phase-sensitive inversion-recovery (IR) magnetic resonance (MR) imaging eliminates the need to find the precise inversion time (TI) to null the signal of normal myocardium to achieve high contrast between infarcted and normal myocardium.Informed consent was obtained from each patient for this prospective MR imaging research study, which was approved by the institutional review board. Twenty patients (16 men; four women; mean age, 56 years +/- 12.3) who experienced Q-wave myocardial infarction 2 weeks earlier were examined with a 1.5-T MR system 10 minutes after administration of 0.1 mmol per kilogram of body weight gadobenate dimeglumine. To determine the optimal TI, a TI scout sequence was used. A segmented two-dimensional IR turbo fast low-angle shot (FLASH) sequence and a segmented two-dimensional IR true fast imaging with steady-state precession (FISP) sequence that produces both phase-sensitive and magnitude-reconstructed images were used at TI values of 200-600 msec (TI values were varied in 100-msec steps) and at optimal TI (mean value, 330 msec). Contrast-to-noise ratios (CNRs) of normal and infarcted myocardium and the area of infarcted myocardium were determined. Magnitude-reconstructed IR turbo FLASH images were compared with magnitude-reconstructed and phase-sensitive IR true FISP images. Two-tailed unpaired sample Student t test was used to compare CNRs, and two-tailed paired-sample Student t test was used to compare area of infarction.Mean CNR of images acquired with IR turbo FLASH and IR true FISP (phase-sensitive and magnitude-reconstructed images) at optimal TI (mean value, 330 msec) were 6.6, 6.2, and 6.1, respectively. For a TI of 200 msec, CNR values were -4.3, -4.0, and 7.2, respectively; for TI of 600 msec, CNR values were 3.1, 3.3, and 4.3, respectively. Area of infarcted myocardium was underestimated on magnitude-reconstruction images (P = .002-.03) for short TI values (ie, 200 msec) for both sequences and for a TI of 300 msec for IR true FISP but not on phase-sensitive reconstructed IR true FISP images when compared with IR turbo FLASH images obtained at optimal TI.Phase-sensitive image reconstruction results in reduced need for precise choice of TI and more consistent image quality.

To compare a hybrid magnetic resonance (MR) angiography protocol with selective digital subtraction angiography (DSA) in patients with critical limb ischemia.The study was approved by the institutional review board, and written consent was obtained from all patients. Pretreatment DSA and hybrid MR angiography were performed in 19 consecutive patients (15 men, four women; mean age, 69.8 years; range, 44-86 years). Hybrid MR angiography included submillimeter dual-phase three-dimensional gadolinium-enhanced MR angiography in lower calf and foot, and four-station bolus-chase MR angiography in pelvis, thigh, and upper calf. Three readers identified the target lesion and inflow and outflow segments and determined treatment (bypass graft placement, percutaneous transluminal angioplasty, conservative management, amputation). Results of interobserver and intermethod comparisons were expressed as percentage of agreement and 95% confidence interval (CI).On hybrid MR angiograms, no substantial venous overlay was present and image quality was excellent or adequate in 18 (95%) of 19 limbs. Readers 1, 2, and 3 selected the identical target lesion on the DSA image and the MR angiogram in 18, 17, and 18 of 18 comparable limbs, respectively. Mean percentage of agreement for readers 1 and 3 was 100% (95% CI: 81%, 100%) and for reader 2 was 94% (95% CI: 73%, 100%). Agreement of all three readers was superior with use of MR angiography for determination of inflow segments (13 [72%] of 18 limbs) and outflow segments (17 [94%] of 18 limbs), compared with agreement with use of DSA (13 [68%] of 19 inflow segments, 10 [53%] of 19 outflow segments). Agreement in therapy decisions was higher with DSA (15 [79%] of 19) than with MR angiography (11 [61%] of 18).Preliminary data strongly support the combination of submillimeter dual-phase MR angiography in lower calf and foot with four-station bolus-chase MR angiography to extend the utility of MR angiography to patients with critical limb ischemia.

To evaluate multi- and single-detector row computed tomographic (CT) depiction of anatomic landmarks of temporal bone.Institutional review board approval and written informed consent were obtained. In 50 temporal bones, transverse and coronal single-detector row CT images were compared with transverse and reformatted coronal multi-detector row CT images obtained of additional 50 temporal bones. Two radiologists evaluated images. Visibility of 50 landmarks was scored with a five-point quality rating scale. Fisher exact test, kappa statistics, and Mann-Whitney U test were used to evaluate imaging technique and landmark visibility.In delineating landmarks, total interobserver agreement was higher (P.001) for transverse multi- than for single-detector row CT images. In 60% of landmarks, interobserver agreement was higher (P.001) for transverse multi- than for single-detector row CT images. In 20% of landmarks, there was no difference, and in another 20% of landmarks, interobserver agreement was higher (P.01) for single-detector row CT. Total interobserver agreement was higher (P.01) for coronal multi-detector row reformations than for coronal single-detector row images. In 58% of landmarks, interobserver agreement was higher (P.001) for coronal multi-detector row reformations than for coronal single-detector row images, while there was no difference in 8%. In 34% of landmarks, interobserver agreement was higher (P.001) for coronal single-detector row images. Frequency of detected landmarks was higher for transverse (82%) and coronal (88%) multi-detector row images than for corresponding single-detector row images. In 72% of landmarks, transverse multi-detector row images were (P.05) superior to corresponding transverse single-detector row images in landmark delineation. In 56% of landmarks, reformatted coronal multi-detector row images were (P.05) superior to coronal single-detector row images in landmark delineation.Multi-detector row CT images, including reformations, better delineate temporal bone anatomy than do single-detector row CT images.

To detect hepatocyte-selective enhancement of focal lesions with gadoxetic acid at magnetic resonance (MR) imaging and to correlate enhancement in hepatocyte-selective phases with histopathologic findings and in arterial and portal venous phases with biphasic computed tomographic (CT) findings.Study was supported by local ethics committee; all patients gave written informed consent. In 19 men and 14 women recruited in three clinical studies, histopathologic correlation and CT scans of 41 focal lesions (13 primary malignant lesions, 21 metastases, three adenomas, three cases of focal nodular hyperplasia [FNH], and one cystadenoma) and ultrasonographic confirmation of five cysts were available. MR was performed before and during arterial and portal venous phases and in hepatocyte-selective phases 10 and 20 minutes after injection of gadoxetic acid. Enhancement was evaluated in consensus by two observers. Enhancement pattern and morphologic features during arterial and portal venous phases were correlated between gadoxetic acid-enhanced MR and CT images by means of adjusted chi(2) test.Hepatocyte-selective uptake was observed 10 and 20 minutes after injection in FNH (three of three), adenoma (two of three), cystadenoma (one of one), and highly differentiated hepatocellular carcinoma (HCC [grade G1], two of four). Uptake was not detected in metastases (21 of 21), cholangiocarcinoma (three of three), combined hepatocellular cholangiocarcinoma (one of one), undifferentiated carcinoma (one of one), moderately or poorly differentiated HCC (grade G2-G3) (four of four), HCC (grade G1, two of four), adenoma with atypia (one of three), or cysts (five of five). During arterial and portal venous phases, there was high overall agreement rate of 0.963 between gadoxetic acid-enhanced MR and CT (simultaneous 95% confidence interval: 0.945, 0.981).Liver-specific enhancement of focal lesions is hepatocyte selective and correlates with various histopathologic diagnoses regarding presence of certain hepatocytic functions. Arterial and portal venous MR images obtained with gadoxetic acid are comparable to those of CT.

To investigate image quality and vascular delineation of multi-detector row computed tomographic (CT) angiography at various kilovoltage settings.Thirty patients were investigated with a standardized CT protocol, with three groups of 10 consecutive patients examined at 80, 120, and 140 kV, respectively. Three blinded readers independently evaluated images and graded image quality parameters, diagnostic confidence, and vascular delineation of intracranial arteries and veins. Vascular CT attenuation values, CT dose indices, and dose length products were assessed quantitatively. For data analysis, a Kruskal-Wallis nonparametric rank F test was used to identify trends and variables that required modeling attention. A proportional odds multinomial regression model was then fit with generalized estimating equations to account for the correlated nature of the data.Image quality was rated higher with higher kilovoltage settings (P.001). The severity of imaging artifacts was higher with lower kilovoltage settings (P.001), while the subjectively rated vessel contrast was lower in the 80-kV group than in the 120-kV group and the 140-kV group (P.05). Diagnostic confidence was higher in the 120-kV group and 140-kV group (P.005). Vascular delineation was higher with higher kilovoltage settings for most arterial and venous structures. Differences were more significant for structures in close topographic proximity to bone and for subsegmental arteries and were less significant and, in parts, not significant for the main arterial branches and the large venous sinus. Attenuation values were higher with lower kilovoltage settings (P.05). The mean dose length product could be reduced from 594 mGy. cm in the 140-kV group to 152 mGy.cm in the 80-kV group.This multireader study of image quality and vessel delineation with cranial multi-detector row CT angiography at various kilovoltage settings demonstrated a superiority of higher voltages with most pronounced effects for vessels adjacent to bone and subsegmental arteries.

To evaluate the occurrence, location, and shape of the fluid sign in acute osteoporotic and neoplastic vertebral compression fractures at magnetic resonance (MR) imaging.The study group comprised 87 consecutive patients with acute vertebral compression fractures due to osteoporotic (n = 52) or neoplastic (n = 35) infiltration. The MR imaging protocol included nonenhanced T1-weighted spin-echo and short inversion time inversion-recovery sequences and a 1.5-T system. Readers blinded to the outcome documented the occurrence, shape, and location of the fluid sign with consensus. The fluid sign was correlated with the cause, age, and severity of the fracture. The diagnosis was confirmed with surgery, follow-up MR imaging, clinical follow-up, or unequivocal imaging findings. Wilcoxon and chi(2) tests were used to assess significance.In fractured vertebral bodies, the fluid sign was adjacent to the fractured end plates and exhibited signal intensity isointense to that of cerebrospinal fluid. The fluid sign was linear (n = 16), triangular (n = 5), or focal (n = 2) and was significantly associated with osteoporotic fractures (21 [40%] of 52; P.001). The fluid sign occurred in two (6%) of 35 neoplastic compression fractures. Histologic examination demonstrated osteonecrosis, edema, and fibrosis at the site of the fluid sign. There was a tendency toward older fractures exhibiting the fluid sign, but this relationship was not significant (P.05). In osteoporotic fractures, the fluid sign was significantly associated with fracture severity (P.05).The fluid sign is featured in acute vertebral compression fractures that show bone marrow edema. It can be an additional sign of osteoporosis and rarely occurs in metastatic fractures.

To compare different reconstruction thicknesses of thin-collimation multi-detector row spiral computed tomographic (CT) data sets of the chest for the detection of subsegmental pulmonary emboli.A multi-detector row spiral CT protocol for the diagnosis of pulmonary embolism was used that consisted of scanning the entire chest with 1-mm collimation within one breath hold. In 17 patients with central pulmonary embolism, the raw data were used to perform reconstructions with 1-mm, 2-mm, and 3-mm section thicknesses. For each set of images, each subsegmental artery was independently graded by three radiologists as open, containing emboli, or indeterminate.For the rate of detection of emboli in subsegmental pulmonary arteries, use of the 1-mm section width yielded an average increase of 40% when compared with the use of 3-mm-thick sections (P.001) and of 14% when compared with the use of 2-mm-thick sections (P =.001). With the use of 1-mm sections versus 3-mm sections, the number of indeterminate cases decreased by 70% (P =.001). Interrater agreement was substantially better with the use of 1-mm and 2-mm sections than with the use of 3-mm sections.For the diagnosis of subsegmental pulmonary emboli at multi-detector row CT, the use of 1-mm section widths results in substantially higher detection rates and greater agreement between different readers than the use of thicker sections.

To determine differences in the signal intensity (SI) time courses at oxygen-enhanced magnetic resonance (MR) lung imaging in healthy volunteers and patients with pulmonary diseases and to correlate these differences with pulmonary diffusing capacity.Seventeen patients with pulmonary diseases and 11 healthy volunteers underwent oxygen-enhanced MR imaging while they breathed room air and 100% oxygen. A turbo spin-echo sequence with global or section-selective inversion pulses was used. For postprocessing, SI slope maps during the breathing of 100% oxygen were calculated. Mean SI slope and SI change values were compared with the diffusing capacity of the lung for carbon monoxide (DLCO).The SI slopes were significantly different for patients and volunteers (Por = .05, Mann-Whitney U test). Linear correlations were detected between the DLCO and SI slopes for the section-selective inversion pulse (r(2) = 0.81) and the global inversion pulse (r(2) = 0.74). A lower correlation was associated with the SI change for the section-selective pulse (r(2) = 0.04; global pulse, r(2) = 0.81). Regional differences were seen in the SI slope and SI change maps. These differences correlated with findings on radiographs and computed tomographic scans.The SI slope during the breathing of 100% oxygen allows spatially resolved assessment of the pulmonary diffusion capacity.

To assess the ability of postmortem radiography and magnetic resonance (MR) imaging to depict occult cervical spine injuries as compared with anatomic and pathologic findings.The cervical spines of 10 adult accident victims underwent radiography and MR imaging, with T1-weighted, fast spin-echo T2-weighted, and four gradient-echo pulse sequences. The frozen specimens were cut into 3-mm-thick slices (sagittal plane) and photographed, and microfocus radiographs were obtained. Imaging findings were compared with the anatomic and pathologic findings.Eight of the 10 specimens had 28 posttraumatic lesions: three fractures (two missed at the initial MR imaging reading), 10 facet joint capsule lesions with bleeding, five soft-tissue and ligament lesions, eight disk lesions, and two spinal cord lesions. Radiography depicted one lesion (4%). Two partial ruptures of the anterior annulus fibrosus were depicted at only MR imaging. Initially, 11 of 28 lesions were detected on MR images; retrospectively, 17 of 28 lesions were correlated with anatomic findings.Soft-tissue and intervertebral disk and ligament injuries account for 89% (25 of 28) of posttraumatic cervical spine lesions detected on postmortem images. Occult lesions, including apophyseal joint injuries, were found in clinically noninjured cervical spines. MR imaging was limited in the depiction of discrete lesions when T1-weighted non-fat-saturated, fast spin-echo T2-weighted, and gradient-echo pulse sequences were used.

To provide intraarterial chemotherapy of the liver in 30 outpatients with colorectal cancer metastases and other malignancies, 32 catheter-port systems were implanted percutaneously via the femoral artery. Mean patency was 229 days. Percutaneous placement was feasible and safe. Compared with surgical placement, the overall complication rate (12%) was comparable or less.

To evaluate gadobenate dimeglumine (Gd-BOPTA) for dynamic and delayed magnetic resonance (MR) imaging of focal liver lesions.In 126 of 214 patients, MR imaging was performed before Gd-BOPTA administration, immediately after bolus administration of a 0.05- mmol/kg dose of Gd-BOPTA, and 60-120 minutes after an additional intravenously infused 0.05-mmol/kg dose. In 88 patients, imaging was performed before and 60-120 minutes after a single, intravenously infused 0.1-mmol/kg dose. T1- and T2-weighted spin-echo and T1-weighted gradient-echo images were acquired. On-site and blinded off-site reviewers prospectively evaluated all images. Intraoperative ultrasonography, computed tomography (CT) during arterial portography, and/or CT with iodized oil served as the reference methods in 110 patients.Significantly more lesions were detected on combined pre- and postcontrast images compared with on precontrast images alone (P. 01). All reviewers reported a decreased mean size of the smallest detected lesion and improved lesion conspicuity on postcontrast images. All on-site reviewers and two off-site reviewers reported increased overall diagnostic confidence (P.01). Additional lesion characterization information was provided on up to 109 (59%) of 184 delayed images and for up to 50 (42%) of 118 patients in whom dynamic images were assessed. Gd-BOPTA would have helped change the diagnosis in 99 (47%) of 209 cases and affected patient treatment in 408 (23%) of 209 cases.Gd-BOPTA increases liver lesion conspicuity and detectability and aids in the characterization of lesions.

To determine whether electrocardiographic (ECG) gating improves image quality of thin-section computed tomographic (CT) scans of the lung obtained with a subsecond CT scanner.Thin-section CT was performed in 35 patients by using standard techniques. Three additional sections were obtained in each patient with prospective ECG gating at corresponding levels of the paracardiac lung parenchyma. Non-ECG-gated and ECG-gated sections were then rated in blinded fashion by three experienced radiologists for overall image quality, spatial resolution, and diagnostic value and for different types of respiratory and cardiac motion artifacts.ECG gating helped significantly reduce artifacts caused by cardiac motion (i.e., distortion of pulmonary vessels, double images, or blurring of the cardiac border) (P.05). ECG gating did not reduce respiratory motion artifacts. In patients with heart rates of less than 76 beats per minute, ECG gating significantly improved overall image quality (P = .041). ECG gating was not perceived to increase the diagnostic value of thin-section CT scans.ECG gating improves image quality of thin-section CT scans of the lung by reducing cardiac motion artifacts that may mimic disease. It must be established whether ECG gating can help increase the diagnostic accuracy of thin-section CT for the evaluation of subtle parenchymal disease.

To determine if hypointense lesions clearly outline on T2-weighted fast spin-echo (SE) magnetic resonance (MR) images obtained during coagulative interstitial laser-induced thermotherapy (LITT) of a prostate with benign hyperplasia.In six patients with benign prostatic hyperplasia (BPH), 12 LITT treatments were followed online with repetitive axial T2-weighted fast SE imaging (repetition time, 3,700 msec; echo time, 138 msec; acquisition time, 19 seconds). Development, time course, correlation with interstitial tissue temperature, and diameters of hypointense lesions around the laser diffusor tip were investigated. Lesion diameters on T2-weighted images acquired during LITT were compared with diameters of final lesions on T2-weighted images and unperfused lesions on enhanced T1-weighted SE images obtained at the end of therapy.Hypointense lesions developed within 20-40 seconds of LITT. Average correlation coefficients between interstitial temperature development and signal intensity development were 0.92 during LITT and 0.90 after LITT. Regression slopes were significantly steeper during LITT (0.67% signal intensity change per degree Celsius) than after LITT (0.47% per degree Celsius; P = .038). Lesions remained visible after LITT for all procedures. Average maximum diameters of lesions were 1-3 mm larger during LITT than after LITT (P = .0006-.019).Repetitive T2-weighted fast SE MR imaging during interstitial coagulative LITT of BPH demonstrates the development of permanent hypointense prostate lesions. However, posttherapeutic lesion diameters tend to be overestimated during LITT.