Sixteen-slice spiral CT versus MR imaging for the assessment of left ventricular function in acute myocardial infarction

The aim of this study was to assess global left ventricular (LV) function and regional wall motion using retrospectively ECG-gated 16-slice computed tomography (CT) in comparison with magnetic resonance imaging (MRI). Twenty-one patients (18 male, 65.5±8.6 years) with acute myocardial infarction underwent multislice spiral CT (MSCT) and MRI. From manually drawn endo- and epicardial contours, LV volumes including myocardial mass, peak filling rate (PFR), peak ejection rate (PER), time to PER (TPER) and time from end-systole to PFR (TPFR) were calculated. Regional wall motion was assessed from cine loops using a 16-segment model of the left ventricle. LV function was analyzed using the Bland–Altman method, Pearsons correlation coefficient, multivariate analysis and post hoc t tests. Regional wall motion was evaluated with weighted kappa-statistics. Multivariate analysis revealed significant differences for global LV function as determined by MSCT and MRI. Post hoc t-tests showed significant differences for end-diastolic volume (EDV), PFR and TPER (P<0.05), while there was a good agreement for the LV volumes with an ejection fraction of 46.9±8.4% for MSCT and 46.9±8.9% for MRI. PER, PFR, TPER and TPFR presented a poor correlation and a wide range of scattering between MSCT and MRI. Regional wall motion scores showed a good agreement with =0.791. Sixteen-slice spiral CT allows for reliable assessment of LV volumes, but is not yet suited for the evaluation of all functional parameters. Assessment of regional wall motion at rest is feasible.     

Comparison of thallium-201 and technetium-99m teboroxime myocardial single photon emission tomography with coronary arteriography

Myocardial single photon emission tomography (SPET) using technetium-99m teboroxime (teboroxime) was studied and the results compared with those of thallium-201(thallium) SPET and coronary arteriography in 19 patients. Resting teboroxime SPET was performed initially. Two hours later, exercise teboroxime SPET was performed. Exercise ergometer tests for both teboroxime and thallium were carried out in a supine position. The levels of exercise achieved for both tests were similar. Agreement for the identification of myocardial segments between thallium SPET and teboroxime SPET was 147/171(86%) (NS). When a significant stenosis was defined as 75% or 50%, agreement between two radiopharmaceuticals for the detection of diseased vessels was 89% (NS, = 0.601) or 88% (NS, = 0.713), respectively. In only 2/19 cases were inferior and posterior segments (3/171) difficult to interpret in teboroxime SPET due to hepatic activity. Thus, teboroxime SPET with a short data acquisition time resulted in a rapid completion for each study and had a good correlation with thallium SPET. Offprint requests to: M. Oshima, M.D., Ph.D. Department of Radiology Nagoya First Red Cross Hospital     

Low-field versus high-field MRI in diagnosing breast disorders

We evaluated the performance of low-field MRI in breast disorders by comparing it with high-field MRI and biopsy results. Twenty-eight consecutive patients who were able to undergo two magnetic resonance examinations on following days were examined by high-field and low-field MRI. After T1-weighted sagittal images had been obtained a dynamic 3D axial study was performed followed by the acquisition of contrast-enhanced T1-weighted sagittal images. The images were analyzed separately by two radiologists paying attention to lesion morphology and enhancement kinetics. Six patients had problems in both breasts (34 breasts studied). The results were compared with biopsy results of 27 breasts. There were 16 malignant lesions, two fibroadenomas and nine other benign lesions. The inter-magnetic-resonance-scanner value was 0.77 (substantial agreement), while the interobserver value was 0.86 and 0.81 at low and high field, respectively (excellent agreement). The sensitivity was 100 and 100%, the specificity was 82 and 73% and the accuracy was 93 and 89% at low and high field, respectively. The mean lesion size was 2 cm and the smallest malignant lesion was 8 mm in diameter. Low-field MRI is a promising tool for breast imaging. Larger materials and smaller lesions are needed to evaluate its true sensitivity and specificity.     

Local Administration of NF-κ B Decoy Oligonucleotides to Prevent Restenosis after Balloon Angioplasty: An Experimental Study in New Zealand White Rabbits

Purpose To evaluate the efficacy of NF- B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits.Materials and Methods In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF- B in two different concentrations (1 g: n=14; 10 g: n=8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed.Results NF- B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF- B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm² using 1 g NF- B ODN compared to 0.98 mm² in the control group. The higher dose resulted in a neointimal area of 0.97 mm² compared to 1.07mm² at the control side.Conclusions Local drug delivery of NF- B ODN using the channeled balloon catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.     

Usefulness of brain <Superscript>99m</Superscript>Tc-TRODAT-1 SPET for the evaluation of Parkinson’s disease

Nigral dopaminergic projections to the striatum are targeted in Parkinsons disease (PD). The extent of the degeneration of the dopaminergic system in PD can be visualised by dopamine transporter imaging using single-photon emission tomography (SPET). In this study in 188 patients with PD, we analysed the image patterns and compared them with the clinical features in order to verify the usefulness of technetium-99m TRODAT-1 brain SPET in the evaluation of patients with PD. Two independent readers visually assessed SPET slices from three brain axes according to a fine visual scale; results were also grouped according to a rough visual scale. Results of both visual and semi-quantitative analyses were compared among patients with different stages of PD and healthy controls. There was good agreement between the readers in the interpretation of the image patterns [kappa statistic ()=0.85 for the presence of PD; =0.88 for the rough scale and 0.81 for the fine scale]. Good concordance was obtained when visual interpretation was used to evaluate the presence of PD (sensitivity =98%, specificity =86%, =0.85). Semi-quantitative analyses revealed significant negative correlations between both striatal and putaminal uptake and disease severity as assessed using the Hoehn and Yahr scale (=–0.89 and –0.93 respectively). An apparent decrease in striatal uptake in early PD, hardly discernible from the uptake level in advanced PD, was commonly found in visual analyses. The results suggest that both visual and semi-quantitative analyses of ^99mTc-TRODAT-1 SPET images reflect neurodegeneration in PD, and that ^99mTc-TRODAT-1 SPET represents an adequate means for evaluation of the status of patients with PD.     

Comparison of 99mTc-sestamibi/18FDG DISA SPECT with PET for the detection of viability in patients with coronary artery disease and left ventricular dysfunction

Purpose Dual-isotope simultaneous acquisition (DISA) single-photon emission computed tomography (SPECT) is an attractive technique as it permits assessment of both myocardial glucose metabolism and perfusion within a single session, but few data on its accuracy for the assessment of viability are available as yet. In the present study, DISA SPECT was compared with positron emission tomography (PET) for the detection of myocardial viability in normal and dysfunctional left ventricular (LV) myocardium.Methods Fifty-eight patients with chronic coronary artery disease and LV dysfunction (LV ejection fraction 33±12%) were studied. Patients underwent a 1-day dipyridamole stress ^99mTc-sestamibi/¹⁸F-fluorodeoxyglucose (¹⁸FDG) DISA SPECT and ¹³N-ammonia/¹⁸FDG PET protocol. Within 1 week, resting MRI was performed to assess contractile function. Comparison of PET and SPECT data was performed using both visual and quantitative analysis.Results The correlation of normalised activities of the flow tracers ^99mTc-sestamibi and ¹³N-ammonia was good (r=0.82; p<0.001). The correlation between the two ¹⁸FDG studies was also good (r=0.83; p< 0.001). The agreement for the assessment of viability for all segments between DISA SPECT and PET was 82%, with a -statistic of 0.59 (95% CI 0.53–0.64), without a significant difference; in dysfunctional segments only, the agreement was 82%, with a -statistic of 0.63 (95% CI 0.56–0.70), without a significant difference. When the DISA SPECT data were analysed visually, the agreement between DISA SPECT and PET was 83%, with a -statistic of 0.58 (95% CI 0.52–0.63), without a significant difference. Moreover, there was no significant difference between visual and quantitative DISA SPECT analysis for the detection of viability.Conclusion This study shows an overall good agreement between ^99mTc-sestamibi/¹⁸FDG DISA SPECT and PET for the assessment of myocardial viability in patients with severe LV dysfunction. Quantitative or visual analysis of the SPECT data did not influence the agreement with PET, suggesting that visual assessment may be sufficient for clinical purposes.     

Study of ECG-gated thallium-201 myocardial scintigraphy: Is imaging time a limiting factor?

Twenty patients underwent gated synchronized ²⁰¹Tl myocardial scanning (TMS). Twelve also performed a rest blood pool multigated acquisition (MUGA) study. A static image was obtained by adding all the gated frames of the study. In this way we found the conventional static study quite unnecessary.Comparing the gated TMS to the static one revealed significantly improved resolution in the gated images and additional information concerning wall motion and myocardial thickness. Close agreement was found with results of MUGA studies of the same patients.By the addition of diastolic frames the imaging time needed to obtain improved image quality was found to be not more than 10 min per view. The exclusion of imaging time as a limiting factor for gated TMS is stressed.     

Sequential 123I-iododexetimide scans in temporal lobe epilepsy: comparison with neuroimaging scans (MR imaging and 18F-FDG PET imaging)

Purpose Muscarinic acetylcholine receptors (mAChRs) play an important role in the generation of seizures. Single-photon emission computed tomography (SPECT) with ¹²³I-iododexetimide (IDEX) depicts tracer uptake by mAChRs. Our aims were to: (a) determine the optimum time for interictal IDEX SPECT imaging; (b) determine the accuracy of IDEX scans in the localisation of seizure foci when compared with video EEG and MR imaging in patients with temporal lobe epilepsy (TLE); (c) characterise the distribution of IDEX binding in the temporal lobes and (d) compare IDEX SPECT and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in identifying seizure foci.Methods We performed sequential scans using IDEX SPECT imaging at 0, 3, 6 and 24 h in 12 consecutive patients with refractory TLE undergoing assessment for epilepsy surgery. Visual and region of interest analyses of the mesial, lateral and polar regions of the temporal lobes were used to compare IDEX SPECT, FDG PET and MR imaging in seizure onset localisation.Results The 6-h IDEX scan (92%; =0.83, p=0.003) was superior to the 0-h (36%; =0.01, p>0.05), 3-h (55%; =0.13, p>0.05) and 24-h IDEX scans in identifying the temporal lobe of seizure origin. The 6-h IDEX scan correctly predicted the temporal lobe of seizure origin in two patients who required intracranial EEG recordings to define the seizure onset. Reduced ligand binding was most marked at the temporal pole and mesial temporal structures. IDEX SPECT was superior to interictal FDG PET (75%; =0.66, p=0.023) in seizure onset localisation. MR imaging was non-localising in two patients in whom it was normal and in another patient in whom there was bilateral symmetrical hippocampal atrophy.Conclusion The 6-h IDEX SPECT scan is a viable alternative to FDG PET imaging in seizure onset localisation in TLE.     

Are digital images good enough? A comparative study of conventional film-screen vs digital radiographs on printed images of total hip replacement

The aim of this study was to evaluate the inter- and intra-observer variability and to find differences in diagnostic safety between digital and analog technique in diagnostic zones around hip prostheses. In 80 patients who had had a total hip replacement (THR) for more than 2 years, a conventional image and a digital image were taken. Gruens model of seven distinct regions of interest was used for evaluations. Five experienced radiologists observed the seven regions and noted in a protocol the following distances: stem–cement; cement–bone; and stem–bone. All images were printed on hard copies and were read twice. Weighted kappa, _w, analyses were used. The two most frequently loosening regions, stem–cement region 1 and cement–bone region 7, were closely analyzed. In region 1 the five observers had an agreement of 86.75–97.92% between analog and digital images in stem–cement, which is a varied _w 0.29–0.71. For cement–bone region 7 an agreement of 87.21–90.45% was found, which is a varied _w of 0.48–0.58. All the kappa values differ significantly from nil. The result shows that digital technique is as good as analog radiographs for diagnosing possible loosening of hip prostheses.     

Gray-scale three-dimensional sonography of thyroid nodules: feasibility of the method and preliminary studies

The aim of the study was differential evaluation of new and classical sonographic features of benign thyroid nodules and thyroid cancer with three-dimensional gray-scale sonography and evaluation of the effectiveness of the thin-slice surface rendered images in comparison with multiplanar reformation (MPR) presentation. Fifty-four thyroid nodules were interactively evaluated with thin-slice smooth surface rendering: shape in the c-plane (parallel to the probe) and evaluation of echogenicity, margins and calcification/microcalcification-like echogenic foci in the a-plane (plane of the probe). Evaluation of the level of agreement in readers interpretation and between sonographic techniques was performed using the statistic. Surface rendering permitted visualization of the shape of the nodule in the c-plane in all cases, in contrast to only up to 48% of cases in MPR evaluation. Lobulated nodule shape in the c-plane was 82–100% sensitive and 47–53% specific in diagnosis of carcinoma. Surface rendered images showed more calcification/microcalcification-like echogenic foci than MPR ones. The level of agreement between the observers in the evaluation of features of thyroid nodules and the agreement between features of thyroid nodules on MPR and surface-rendered images showed at least moderate reproducibility (0.41). Three-dimensional thin-slice surface rendering sonography appears to be a feasible and effective method for thyroid nodule evaluation.     

Early postoperative adherence of matrix-induced autologous chondrocyte implantation for the treatment of full-thickness cartilage defects of the femoral condyle

Matrix-induced autologous chondrocyte implantation (MACI) is a tissue-engineering technique for the treatment of full-thickness articular cartilage defects and requires the use of a three-dimensional collagen type I–III membrane seeded with cultured autologous chondrocytes. The cell-scaffold construct is implanted in the debrided cartilage defect and fixed only with fibrin glue, with no periosteal cover or further surgical fixation. In a clinical pilot study, the MACI technique was used for the treatment of full-thickness, weight-bearing chondral defects of the femoral condyle in 16 patients. All patients were followed prospectively and the early postoperative attachment rate, 34.7 days (range: 22–47) after the scaffold implantation, was determined. With the use of high-resolution magnetic resonance imaging (MRI), the transplant was graded as completely attached, partially attached, or detached. In 14 of 16 patients (87.5%), a completely-attached graft was found, and the cartilage defect site was totally covered by the implanted scaffold and repair tissue. In one patient (6.25%), a partial attachment occurred with partial filling of the chondral defect. A complete detachment of the graft was found in one patient (6.25%), which resulted in an empty defect site with exposure of the subchondral bone. Interobserver variability for the MRI grading of the transplants showed substantial agreement (=0.775) and perfect agreement (_w=0.99). In conclusion, the implantation and fixation of a cell-scaffold construct in a deep cartilage defect of the femoral condyle with fibrin glue and with no further surgical fixation leads to a high attachment rate 34.7 days after the implantation, as determined with high resolution MRI.     

PET and MR imaging in a neuro-behçet syndrome

Positron emission tomography (PET) and magnetic resonance imaging (MRI) studies were performed on a case of neuro-Behçet's syndrome. In accordance with the clinical signs, FDG PET (using¹⁸F-labeled 2-F-2-desoxyglucose) revealed disseminated storage defects in the cerebrum and cerebellum. Focal regions of enhanced signal intensity were demonstrated in the parietal white matter of the cerebrum in T2-weighted images and in the brain stem by MRI.This article was presented at the 1st EEC workshop on accuracy determination in PET, January 19–20th. 1989 Pisa, Italy (COMAC-BME Concerted Project Characterization and Standardization of PET Instrumentation)     

Proportional anatomical stereotactic atlas for visual interpretation of brain SPET perfusion images

A semi-automatic method was developed to determine the anterior (AC) and posterior (PC) commissures on brain single-photon emission tomographic (SPET) perfusion images, and then to draw the proportional anatomical Talairach's grid on each axial SPET image. First, the AC-PC line was defined on SPET images from the linear regression of four internal landmarks (frontal pole of the brain, inferior limit of the anterior corpus callosum, sub-thalamic point and occipital pole). Second, the SPET position of AC and PC points on the AC-PC line was automatically determined from measurements made on hard copies of magnetic resonance (MR) images of the patients. Finally, a proportional Talairach's grid was automatically drawn on each axial SPET image. To assess the accuracy of localization of AC and PC points, co-registered technetium-99m hexamethylpropylene amine oxime SPET and MR images from 11 subjects were used. The mean displacements between estimated points on SPET and true points on MRI (x=sagittal, y=frontal and z=axial displacement) were calculated. The mean displacements (in mm) were x=–1.4±1.8, y=–1.7±3.3 and z=–1.1±2.5 for AC, and x=–1.8±1.8, y=0.3±3.2 and =–1.3±2.7 for PC. These displacements represented an error of less than 5 mm at the anterior or posterior pole of the brain or at the vertex. Intra- and inter-observer comparisons did not reveal significant differences in mean displacements. Thus, this semi-automatic method results in reproducible and accurate stereotactic localization of SPET perfusion abnormalities. This method can be used routinely for repeat follow-up studies in the same subject as well as in different individuals without requiring SPET MRI co-registration.     

Reporting of ventilation perfusion images for pulmonary embolism: Accuracy and precision

Thirty-four hospital patients with suspected pulmonary embolism (PE) had ventilation perfusion (VP) imaging after pulmonary angiography to assess the performance of highly specific criteria for diagnosis of PE and to evaluate the precision of image reporting. A diagnostic result was obtained from VP imaging in 21 of 34 patients giving a sensitivity for PE of 80% and a specificity of 100% in this subgroup. Six of 11 patients with PE had an indeterminate study which reduced the overall sensitivity of the technique for PE in the whole group. A critical analysis of image reporting by two readers gave an 85% inter-observer agreement on ranking as diagnostic or indeterminate for PE ( 0.69) and 91%–94% agreement for consensus reproducibility ( 0.82). We conclude that the degree of accuracy and precision of reporting that can be obtained using specific criteria will provide a reliable diagnosis in a significant number of patients suspected of having PE. Consensus reporting by two readers is shown to be more reliable than individual reporting.     

Interobserver variation in the detection of osteopenia by radiography and comparison with dual X-ray absorptiometry of the lumbar spine

In 100 patients (20 male, 80 female) radiographs of the lumbar spine were obtained in both planes, anteroposterior and lateral. Nine readers independently and without specific criteria or training assessed the radiographs for presence of osteopenia in the form of a binary decision. A posteroanterior dual x-ray absorptiometry (PA DXA) measurement of the lumbar spine was performed in all patients using the Hologic QDR 1000 bone densitometer. A bone mineral density (BMD) of 0.83 g/ cm² (T-score about 2 SD and 2.5 SD lower than BMD in normal young female and male subjects respectively) was used as a threshold for the diagnosis of osteopenia. Complete agreement amongst the 9 readers was achieved in 43 patients. In 26 more patients at least 8 readers agreed, -coefficients for interobserver variation ranged from 0.458 to 0.691 for reader pairs. For agreement between the observer ratings and the DXA results, -coefficients ranging between 0.347 and 0.555 were found. The vast majority of readers agreed in the diagnosis of osteopenia in cases where the BMD was less than 0.73 g/cm². Where the BMD was between 0.73 and 1.03 g/cm² a substantial disagreement was found between reader evaluation and DXA measurement, and also amongst the readers. We conclude from our results that osteopenia can reliably be detected from lumbar spine radiographs by all readers only after a substantial amount of BMD is lost. On the other hand, a diagnosis based solely on PA DXA measurement of the spine may also lack accuracy, due to a substantial influence of degenerative changes of the lumbar spine and aortic calcification. Therefore, spine radiographs remain an important cornerstone in the detection and differential diagnosis of osteopenia.     

Relation between wall thickening on gated perfusion SPECT and functional recovery after coronary revascularization in patients with previous myocardial infarction

Purpose This study aimed to evaluate whether wall thickening analysis by gated perfusion single-photon emission computed tomography (SPECT) is useful in predicting functional recovery after revascularization.Methods Forty-one patients with previous myocardial infarction and left ventricular (LV) dysfunction (ejection fraction, EF, 36±6%) who were scheduled for revascularization underwent rest ^99mTc-sestamibi gated SPECT.Results Of 131 akinetic or dyskinetic segments at baseline echocardiography, 82 (63%) recovered after revascularization. Compared with wall thickening analysis, perfusion imaging provided higher sensitivity (78% vs 50%, P<0.0001) and specificity (80% vs 71%, P<0.0005). Among segments with 55% sestamibi uptake (viable), those with detectable wall thickening had a higher likelihood of functional recovery than those with absent wall thickening (95% vs 77%, P<0.05). In segments with improved function, the absence of wall thickening was associated with lower sestamibi activity than was observed when detectable wall thickening was present (58±14% vs 71±13%, P<0.0005). An increase in EF of 5% was detectable in 22 (54%) patients. For the prediction of EF improvement, perfusion imaging provided a higher sensitivity than wall thickening analysis (68% vs 41%, P<0.05), while specificity was not significantly different (68% vs 74%). The prevalence of patients with functional recovery did not change when wall thickening analysis was considered in addition to perfusion status (73% in patients with detectable wall thickening and 70% in those without; P=NS).Conclusion In patients with coronary artery disease, wall thickening analysis by gated perfusion SPECT provides additional information compared with perfusion data for the prediction of segmental functional recovery. However, on a patient basis, wall thickening assessment seems to be of more limited value than perfusion status.     

Hemorrhage associated with “bone crisis” in Gaucher's disease identified by magnetic resonance imaging

Children suffering from Gaucher's disease were examined by magnetic resonance imaging (MRI) during a characteristic episode of bone crisis. An unexpectedly high intramedullary as well as subperiosteal signal was observed on both the T1 and T2-weighted sequences in 5 patients, suggesting a subacute hemorrhage or hematoma. It is conceivable that such a painful hemorrhage is an important component of the bone crisis phenomenon. Furthermore, in these cases this is a specific sign which may enable differentiation of bone crises from other types of bone pain associated with Gaucher's disease.     

Evaluation of carotid stenosis with axial high-resolution black-blood MR imaging

High-resolution axial black-blood MR imaging (BB MRI) has been shown to be able to characterise carotid plaque morphology. The aim of this study was to explore the accuracy of this technique in quantifying the severity of carotid stenosis. A prospective study of 54 patients with symptomatic carotid disease was conducted, comparing BB MRI to the gold standard, conventional digital subtraction X-ray angiography (DSA). The BB MRI sequence was a fast-spin echo acquisition (TE=42 ms, ETL=24, field of view = 100×100 mm, slice thickness = 3.0 mm) at 1.5 T using a custom-built phased-array coil. Linear measurements of luminal and outer carotid wall diameter were made directly from the axial BB MRI slices by three independent blinded readers and stenosis was calculated according to European Carotid Surgery Trial (ECST) criteria. There was good agreement between BB MRI and DSA (intraclass correlation = 0.83). Inter-observer agreement was good (average kappa = 0.77). BB MRI was accurate for detection of severe stenosis (80%) with sensitivity and specificity of 87 and 81%, respectively. Eight cases of DSA-defined moderate stenosis were overestimated as severe by BB MRI and this may be related to non-circular lumens. Axial imaging with BB MRI could potentially be used to provide useful information about severity of carotid stenosis.     

Short tau inversion recovery and proton density-weighted fat suppressed sequences for the evaluation of osteoarthritis of the knee with a 1.0 T dedicated extremity MRI: development of a time-efficient sequence protocol

Aim of this study was to develop a time-efficient sequence protocol for a 1.0 T dedicated MR system to be used for whole-organ scoring of osteoarthritis (OA). Thirty-four knees were examined using a protocol that included fat suppressed fast spin echo proton density weighted sequences (PDFS) in three planes plus a coronal STIR sequence. Two radiologists scored each knee by consensus for five OA features. In separate sessions, all knees were scored using three different combinations of sequences: (1) all four sequences (reference protocol, 16 min 31 s scanning time), (2) three PDFS sequences without STIR (No STIR, 12 min 25 s scanning time) and (3) sagittal and axial PDFS sequences plus a coronal STIR sequence (No PDFS, 11 min 49 s scanning time). Agreement of the readings using both subsets of sequences compared to the reference protocol was evaluated using weighted kappa statistics. -coefficients showed good or excellent agreement for both sequence subsets in comparison to the reference protocol for all assessed features. -coefficients for No PDFS/No STIR: bone marrow abnormalities (0.74/0.67), subarticular cysts (0.84/0.63), marginal osteophytes (0.77/0.71), menisci (0.75/0.79), tibial cartilage (0.71/0.78). Optimization of sequence protocols consisting of three sequences results in time savings and cost efficiency in imaging of knee OA without loss of information over a more time consuming protocol.     

Assessment of myocardial perfusion and viability from routine contrast-enhanced 16-detector-row computed tomography of the heart: preliminary results

To assess the diagnostic accuracy of 16-detector-row computed tomography (16DCT) of the heart in the assessment of myocardial perfusion and viability in comparison to stress perfusion magnetic resonance imaging (SP-MRI) and delayed-enhancement magnetic resonance imaging (DE-MRI). A number of 30 patients underwent both 16DCT and MRI of the heart. Contrast-enhanced 16DCT data sets were reviewed for areas of myocardium with reduced attenuation. Both CT and MRI data were examined by independent reviewers for the presence of myocardial perfusion defects or myocardial infarctions (MI). Volumetric analysis of the hypoperfusion areas in CT and the infarct sizes in DE-MRI were performed. According to MRI, myocardial infarctions were detected in 11 of 30 cases, and perfusion defects not corresponding to an MI were detected in six of 30 patients. CTA was able to detect ten of 11 MI correctly (sensitivity 91%, specificity 79%, accuracy 83%), and detected three of six hypoperfusions correctly (sensitivity 50%, specificity 92%, accuracy 79%). Assessing the volume of perfusion defects correlating to history of MI on the CT images, a systematic underestimation of the true infarct size as compared to the results of DE-MRI was found (P<0.01). Routine, contrast-enhanced 16-detector row CT of the heart can detect chronic myocardial infarctions in the majority of cases, but ischemic perfusion defects are not reliably detected under resting conditions.Dr. Sanzs work is supported in part by a Research Grant (Beca para la Formación en Investigación Post-Residencia) from the Spanish Society of Cardiology.