Biomedical subjects

Maximilian Reiser

Publications and source records attributed to Maximilian Reiser.

At least 19 recordsLinked to original sources

PubMed2006

Assessment of collateralized myocardium with Cardiac Magnetic Resonance (CMR): transmural extent of infarction but not angiographic collateral vessel filling determines regional function and perfusion in collateral-dependent myocardium.

BACKGROUND: Angiographic collateral vessel filling is limited to evaluate collateral-dependent myocardium. We hypothesize, that quantitative assessment of regional myocardial function, perfusion and viability with Cardiac Magnetic Resonance (CMR) adds complementary information to angiography of collateralized myocardium. METHODS: CMR was performed in 30 patients with one chronic occluded coronary artery and no further flow limiting stenosis to assess transmural extend of infarction (TEI), resting perfusion and perfusion during adenosine-induced hyperemia and regional wall thickening (RWT) in collateral-dependent and antegradely-perfused myocardium. Collateral vessels were evaluated by angiography and the Rentrop grade (0-3). RESULTS: In 15 patients with < 50% TEI in collateral-dependent myocardium resting perfusion (1.08+/-0.22 ml/min/g), hyperemia (2.21+/-0.73 ml/min/g) and RWT (4.0+/-2.6 mm) were similar to antegradely-perfused myocardium (rest 1.14+/-0.20 and hyperemia 2.46+/-0.82 ml/min/g, RWT 4.3+/-1.7 mm). In 15 patients with > or = 50% TEI in collateral-dependent myocardium resting perfusion and hyperemia as well as RWT were significantly lower (rest 0.84+/-0.19, p<0.001 and hyperemia 1.34+/-0.43 ml/min/g, p<0.001; RWT 1.0+/-1.0 mm, p<0.0001) compared to antegradely-perfused myocardium. There was an inverse correlation between TEI and resting or hyperemic perfusion or RWT. In contrary, resting perfusion and hyperemia as well as RWT in collateral-dependent myocardium were not different between patients with good (2-3) compared to patients with poor Rentrop grade (0-1). There was no correlation between TEI and Rentrop grade. CONCLUSION: Function and perfusion in collateral-dependent myocardium are preserved, if transmural extent of infarction is limited (< 50%). This is independent of their angiographic collateral vessel filling. Thus, CMR adds complementary information to angiographic standard assessment of collateral vessels.

Aged↗

PubMed2006

Sixty-four slice spiral CT angiography does not predict the functional relevance of coronary artery stenoses in patients with stable angina.

PURPOSE: The aim of this study was to evaluate spiral multidetector computed tomography (MDCT) angiography using 64-slice technique in the detection of functionally relevant coronary artery stenoses (CAS). METHODS: Thirty-eight patients (62+/-11 years, 28 men) with stable angina (26 with suspected and 12 with known coronary artery disease) were investigated using 64-slice MDCT angiography and gated myocardial perfusion SPECT (gated SPECT); a subgroup of 30 patients had additional invasive coronary angiography (ICA). Stenoses with luminal narrowing of >or=50% were defined as "significant" in MDCT angiography and ICA. MDCT angiography was compared with gated SPECT and the combination of gated SPECT plus ICA with respect to the detection of functionally relevant CAS. RESULTS: The sensitivity, specificity and negative and positive predictive values of MDCT angiography in detecting reversible perfusion defects on gated SPECT were 63%, 80%, 94% and 32%, respectively, in vessel-based analysis and 71%, 62%, 72% and 60%, respectively, in patient-based analysis. If only reversible perfusion defects on gated SPECT with CAS >or=50% on ICA were considered, the sensitivity, specificity and negative and positive predictive values were, respectively, 85%, 79%, 98% and 33% for vessel-based analysis and 85%, 59%, 83% and 61% for patient-based analysis. CONCLUSION: Sixty-four slice MDCT angiography failed to predict the functional relevance of CAS, but had a high negative predictive value in the exclusion of functionally relevant CAS in symptomatic patients.

Angina Pectoris↗

PubMed2006

Cardiac magnetic resonance perfusion imaging for the functional assessment of coronary artery disease: a comparison with coronary angiography and fractional flow reserve.

AIMS: Cardiac magnetic resonance perfusion imaging (CMRI) is a promising technique for non-invasive measurement of myocardial perfusion reserve. Fractional flow reserve (FFR) is an established invasive method for functional assessment of coronary artery disease (CAD). To prospectively assess the diagnostic value of CMRI for the detection of haemodynamically significant coronary lesions, compared with coronary angiography (CA) and FFR. METHODS AND RESULTS: Forty-three patients with suspected or known CAD underwent CA, CMRI, and FFR measurement. First pass magnetic resonance perfusion examination was performed during hyperaemia (140 microg/kg/min adenosine over 6 min) and at rest. One hundred and twenty-nine perfusion territories were assessed by semi-quantitative evaluation of signal intensity-time curves using the myocardial perfusion reserve index (MPRI) [upslope(stress(corrected))/upslope(rest(corrected))]. Perfusion territories were categorized as normal (coronary stenosis < or = 50%), intermediate (stenosis > 50% and FFR > 0.75), or severe (stenosis > 50% and FFR < or = 0.75 or total occlusion). MPRI values (+/-SD) were significantly different between the three categories [normal, 2.2 +/- 0.5 vs. intermediate, 1.8 +/- 0.5 (P = 0.005) and intermediate vs. severe, 1.2 +/- 0.3 (P < 0.001)]. An MPRI cut-off value of 1.5 (derived from receiver operating characteristics analysis) distinguished haemodynamically relevant (severe) from non-relevant (normal and intermediate) stenoses with a sensitivity of 88% (CI 74-100%) and a specificity of 90% (CI 84-96%). CONCLUSION: In contrast to earlier studies that compared CMRI with morphological examination (CA) alone, the present study compared CMRI with CA plus a standard invasive functional assessment (FFR) and demonstrated that CMRI is able to distinguish haemodynamically relevant from non-relevant coronary lesions with a high sensitivity and specificity and may therefore contribute to clinical decision-making.

Aged↗

PubMed2006

Comparison of different patient positioning strategies to minimize shoulder girdle artifacts in head and neck CT.

The purpose of this study was to analyze different patient positioning strategies for minimizing artifacts of the shoulder girdle in head and neck CT. Standardized CT examinations of three positioning groups were compared (P: patients pushed their shoulders downwards; D: similar optimization by a pulling device; N: no particular positioning optimization). Parameters analyzed were the length of the cervical spine not being superimposed by the shoulder girdle as well as noise in the supraclavicular space. In groups P and D, the portion of the cervical spine not superimposed was significantly larger than in group N (P: 10.4 cm; D: 10.6 cm; N: 8.5 cm). At the supraclavicular space, noise decreased significantly (P: 12.5 HU; D: 12.1 HU; N: 17.7 HU). No significant differences between the two position-optimized groups (P and D) were detected. Optimized shoulder positioning by the patient increases image quality in CT head and neck imaging. The use of a pulling device offers no additional advantages.

Artifacts↗

PubMed2006

Hard disk online caches in picture archiving and communication systems archives: how big is beautiful?

The objective of our study was to support algorithmic recommendations for the appropriate sizing of picture archiving and communication system (PACS) caches. For a large PACS installation, a detailed analysis of current radiographic (CR), CT and MRI studies (n=400 consecutive studies, respectively) was performed. In this process every available prior examination was also considered. A new algorithmic procedure for appropriate sizing of PACS caches was developed and applied to the given cache implementation. The number of all priors was 7.6+/-12.3. Of them, 61% were relevant priors with an average age of 203+/-385 days. A basic cache (BC) that covers 12 months of current imaging results in a pre-fetching quote of 15.4% (8.6% for 24 months). In the PACS installation examined, a minimal threefold increase in cache capacity was recommended. Studies that are retrieved, prior to viewing, from the long-term archive require additional space in the extended cache (EC). An intimate and mutual interaction between hospital information system (HIS), radiology information system (RIS) and PACS minimizes this requirement and increases the time during which actual image material from the BC is available online. A basic cache size covering actual imaging of 12 months up to 24 months is recommended. The parameters governing the individual dimensions of both cache spaces and a mathematical algorithm are demonstrated.

Algorithms↗

PubMed2006

Amygdala volume and depressive symptoms in patients with borderline personality disorder.

BACKGROUND: Borderline personality disorder (BPD) is characterized by a high prevalence of comorbid psychiatric disorders, including major depression (MD). The aim of this study was to examine whether a co-occurrence of MD is associated with structural changes in the amygdala of BPD patients. METHODS: Twenty-five right-handed, female patients with BPD and 25 matched healthy control subjects were examined. Diagnoses of BPD and MD were made according to DSM IV. Depressive symptomatology was determined with the Hamilton Depression Scale (HAMD). Magnetic resonance imaging scans were performed with 1.5 T Magnetom Vision (Siemens, Erlangen, Germany). The software program "BRAINS" was applied for brain volumetry and segmentation. The amygdala was delineated as "region of interest." RESULTS: Comparison of amygdala volumes between the whole group of BPD patients and control subjects revealed no significant difference. Amygdala volumes in both hemispheres were significantly larger in BPD patients with MD compared with those without MD. There was a significant correlation in BPD patients between left amygdala volume and depressive symptoms as measured by HAMD. CONCLUSIONS: Correlation of amygdala volume with depression in BPD patients might indicate a causal relationship. Future studies should clarify whether amygdala enlargement is a risk factor for MD in BPD patients or a consequence of the affective disorder.

Adult↗

PubMed2006

Volume changes in the menisci and articular cartilage of runners: an in vivo investigation based on 3-D magnetic resonance imaging.

BACKGROUND: Articular cartilage contributes to transferring enormous loads as uniformly as possible from one skeletal segment to the next. Whether it manages this task when subjected to the high repetitive loading cycles occurring during long-distance running and can remain intact is still the topic of controversy. PURPOSE: To investigate the changes in cartilaginous volumes of the tibia, patella, and medial and lateral menisci after extreme dynamic loading as occurs in long-distance runners. STUDY DESIGN: Controlled laboratory study. METHODS: Forty-eight knees of male athletes were studied (38 +/- 14 years). The subjects ran around a predetermined and precisely measured course (5, 10, 20 km), the beginning and end of the run being in the magnetic resonance imaging investigation room. The scan protocol was 60-minute rest period, first measurement, run, 3-minute delay, and second measurement. RESULTS: Overall, there were significant reductions in volume (P < .05) for the patella, tibia, and menisci. There was evidence of significant change after a running distance of 5 km. A further statistical reduction of the volume could only be demonstrated for the medial meniscus after 10 and 20 km. CONCLUSION: Tibial, patellar, and meniscal cartilaginous volumes show not only load-dependent volume changes but also an asymptotic curve. This is the first time that meniscal volume changes due to loading have been used as an indicator of the important mechanical contribution that the menisci make to sustaining the knee during repetitive loading. CLINICAL RELEVANCE: On the basis of the results of this study, the authors assume that the cartilage is able to adapt well to the loads caused by running.

Adult↗

PubMed2006

Cluster analysis of signal-intensity time course in dynamic breast MRI: does unsupervised vector quantization help to evaluate small mammographic lesions?

We examined whether neural network clustering could support the characterization of diagnostically challenging breast lesions in dynamic magnetic resonance imaging (MRI). We examined 88 patients with 92 breast lesions (51 malignant, 41 benign). Lesions were detected by mammography and classified Breast Imaging and Reporting Data System (BIRADS) III (median diameter 14 mm). MRI was performed with a dynamic T1-weighted gradient echo sequence (one precontrast and five postcontrast series). Lesions with an initial contrast enhancement >or=50% were selected with semiautomatic segmentation. For conventional analysis, we calculated the mean initial signal increase and postinitial course of all voxels included in a lesion. Secondly, all voxels within the lesions were divided into four clusters using minimal-free-energy vector quantization (VQ). With conventional analysis, maximum accuracy in detecting breast cancer was 71%. With VQ, a maximum accuracy of 75% was observed. The slight improvement using VQ was mainly achieved by an increase of sensitivity, especially in invasive lobular carcinoma and ductal carcinoma in situ (DCIS). For lesion size, a high correlation between different observers was found (R(2) = 0.98). VQ slightly improved the discrimination between malignant and benign indeterminate lesions (BIRADS III) in comparison with a standard evaluation method.

Algorithms↗

PubMed2006

Accuracy of 64-slice computed tomography to classify and quantify plaque volumes in the proximal coronary system: a comparative study using intravascular ultrasound.

OBJECTIVES: We evaluated the accuracy of a new 64-slice computed tomography (CT) scanner, compared with intravascular ultrasound, to visualize atherosclerosis in the proximal coronary system. BACKGROUND: Noninvasive determination of plaque composition and plaque burden may be important to improve risk stratification. METHODS: In 20 patients, a 64-slice CT scan (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) and an intravascular ultrasound investigation of vessels without stenosis >50% was performed. Diagnostic image quality with 64-slice CT was obtained in 36 vessels in 19 patients. RESULTS: In these vessels, which were divided in 3-mm sections, 64-slice CT enabled a correct detection of plaque in 54 of 65 (83%) sections containing noncalcified plaques, 50 of 53 (94%) sections containing mixed plaques, and 41 of 43 (95%) sections containing calcified plaques. In 192 of 204 (94%) sections, atherosclerotic lesions were excluded correctly. In addition, 64-slice CT enabled the visualization of 7 of 10 (70%) sections revealing a lipid pool and could identify a spotty calcification pattern in 27 of 30 (90%) sections. The correlation coefficient to determine plaque volumes per vessel was r2 = 0.69 (p < 0.001) with an underestimation of mixed and noncalcified plaque volumes (p < 0.03) and a trend to overestimate calcified plaque volumes by 64-slice CT. The interobserver variability to determine plaque volumes was 37%. Interobserver agreement to identify atherosclerotic sections was good (Cohen's kappa coefficient = 0.75). CONCLUSIONS: We conclude that 64-slice CT reveals encouraging results to noninvasively detect different types of coronary plaques located in the proximal coronary system. The ability to determine plaque burden currently is hampered by mainly an insufficient reproducibility.

Coronary Angiography↗

PubMed2006

Comparison of angiography, duplex sonography and intravascular ultrasound for the graduation of femoropopliteal stenoses before and after balloon angioplasty.

The graduation of femoropopliteal stenoses by either digital subtraction angiography (DSA) or duplex sonography remains challenging, particularly after percutaneous transluminal angioplasty (PTA). More accurate assessment of stenosis might be achieved with intravascular ultrasound (IVUS). We investigated the relationship between DSA, IVUS and duplex before and after 32 femoropopliteal PTAs. Over the whole range of stenoses, peak systolic velocity (PSV) and peak velocity ratio (PVR) correlated better with DSA-stenosis (R(2) = .72 and 0.74, respectively, p < 0.01) than with IVUS-stenosis (R(2) = 0.58 and 0.50, p < 0.01). Within the subgroup of preinterventional (51 to 99%) stenoses, PVR was significantly correlated only with DSA-stenosis (R(2) = 0.60, p < 0.01). Severe dissection after PTA was associated with a disproportionate rise in PSV and large discrepancies between IVUS and DSA. Unexpectedly, our data show that intrastenotic flow acceleration assessed by duplex sonography correlates better with DSA- than with IVUS-stenosis. The concordance between duplex sonography, DSA and IVUS was particularly weak in postinterventional measurements, casting some doubt on the reliability of these methods for the assessment of residual stenosis after femoropopliteal PTA.

Angiography, Digital Subtraction↗

PubMed2006

Depiction of low-contrast detail in digital radiography: comparison of powder- and needle-structured storage phosphor systems.

PURPOSE: We sought to evaluate the low-contrast performance of a newly developed needle image plate/line scanner (NIP) computed radiography system in comparison with a standard powder image plate/flying-spot scanner (PIP) system. MATERIALS AND METHODS: A total of 36 images of a CDRAD phantom, simulating low-contrast structures with different drill holes of different diameters, were obtained with both imaging systems using 9 different exposure variables. All images had window and level set to generate consistent density and contrast. In addition, multiscale contrast-dependent contrast amplification was applied to some of the images. All images obtained were printed and presented to a total of 10 observers (5 radiologists, 5 engineers/physicists), who were blinded to both the image plate and parameter setting used. The smallest detectable drill hole depth (= contrast) correctly identified was recorded for each diameter. The median values observed were calculated and tested for statistical differences between PIP and NIP using Student t test for matched pairs (level of significance P < or = 0.05). RESULTS: At all but 2 settings of the variables, NIP images depicted significantly lower contrast levels (= lower depth of drill holes) compared with PIP images. The 2 settings also showed a trend towards better low contrast depiction with NIP. In no case was low contrast performance better using PIP images. CONCLUSION: Images obtained with needle image plate/line scanner provide superior low contrast performance compared with the images obtained with powder image plate/flying-spot scanner.

Observer Variation↗

PubMed2006

Intravascular optical coherence tomography: comparison with histopathology in atherosclerotic peripheral artery specimens.

PURPOSE: Intravascular optical coherence tomography (OCT) is a new imaging modality that provides microstructural information on atherosclerotic plaques and has an axial resolution of 10-20 microm. OCT of coronary arteries characterizes different atherosclerotic plaque components by their distinctive signal patterns. Peripheral human arteries were examined ex vivo by means of OCT, and attempts to distinguish among fibrous, lipid-rich, and calcified atherosclerotic plaques were made based on imaging criteria previously established for coronary arteries. MATERIALS AND METHODS: One hundred fifty-one atherosclerotic arterial segments were obtained from 15 below-knee amputations. OCT imaging criteria for different plaque types (fibrous, lipid-rich, calcified) were established in a subset of 30 arterial segments. The remaining 121 OCT images were analyzed by two independent readers. Each segment was divided into four quadrants. Agreement between histopathology and OCT was quantified by the kappa test of concordance, as were interobserver, intraobserver, and inter-method variability. RESULTS: Four hundred sixty-nine of 484 quadrants (97%) were available for comparison. Sensitivity and specificity for OCT criteria (consensus readers 1 and 2) were 86% and 86% for fibrous plaques, 78% and 93% for lipid-rich plaques, and 84% and 95% for calcified plaques, respectively (overall agreement, 84%). The interobserver and intraobserver reliabilities of OCT assessment were high (kappa values of 0.84 and 0.87, respectively). The inter-method agreement was 0.74 for consensus OCT versus consensus histology. CONCLUSIONS: OCT of peripheral human arteries ex vivo characterized different atherosclerotic plaque types with a high degree of agreement with histopathologic findings. Findings were comparable to those reported for coronary arteries. OCT promises to improve understanding of the progression or regression of peripheral atherosclerosis in vivo.

Adult↗

PubMed2006

Technical description, phantom accuracy, and clinical feasibility for fiducial-free frameless real-time image-guided spinal radiosurgery.

OBJECT: The authors describe the technical application of the Xsight Spine Tracking System, data pertaining to accuracy obtained during phantom testing, and the initial clinical feasibility of using this fiducial-free alignment system with the CyberKnife in spinal radiosurgery. METHODS: The Xsight integrates with the CyberKnife radiosurgery system to eliminate the need for implantation of radiographic markers or fiducials prior to spinal radiosurgery. It locates and tracks spinal lesions relative to spinal osseous landmarks. The authors performed 10 end-to-end tests of accuracy using an anthropomorphic head and cervical spine phantom. Xsight was also used in the treatment of 50 spinal lesions in 42 patients. Dose planning was based on 1.5-mm-thick computed tomography slices in which an inverse treatment planning technique was used. All lesions could be treated using the fiducial-free tracking procedure. Phantom tests produced an overall mean targeting error of 0.52 +/- 0.22 mm. The setup time for patient alignment averaged 6 minutes (range 2-45 minutes). The treatment doses varied from 12 to 25 Gy to the median prescription isodose of 65% (40 to 70%). The tumor volume ranged between 1.3 and 152.8 cm3. The mean spinal cord volume receiving greater than 8 Gy was 0.69 +/- 0.35 cm3. No short-term adverse events were noted during the 1- to 7-month follow-up period. Axial and radicular pain was relieved in 14 of 15 patients treated for pain. CONCLUSIONS: Fiducial-free tracking is a feasible, accurate, and reliable tool for radiosurgery of the entire spine. By eliminating the need for fiducial implantation, the Xsight system offers patients noninvasive radiosurgical intervention for intra- and paraspinal tumors.

Adolescent↗

PubMed2006

Reduced hippocampal volume correlates with executive dysfunctioning in major depression.

OBJECTIVE: Dysfunction of neuronal plasticity or remodelling seems to contribute to the pathopysiology of major depression and may cause the well-documented hippocampal changes in depression. We aimed to investigate whether reduced hippocampal volumes correlate with executive dysfunctioning or memory dysfunctioning or with depression severity. METHODS: We recruited 34 inpatients with a previous or current episode of major depression from the department of psychiatry at the Ludwig-Maximilians University of Munich, Germany. We examined the 34 patients and 34 healthy control subjects with structural high resolution MRI. We assessed cognitive functions with the Wisconsin Card Sorting Test (WCST) and the Rey Auditory Verbal Learning Test (RAVLT) and severity of depression with the Hamilton Depression Rating Scale. RESULTS: Hippocampal volumes and frontal lobe volumes were significantly smaller in patients, compared with healthy control subjects. Furthermore, lower hippocampal volumes were correlated with poorer performance in the WCST. No significant correlations were found between hippocampal volumes and RAVLT performance or severity of depression. CONCLUSIONS: The present findings emphasize that patients with reduced hippocampal volumes show more executive dysfunctions than their counterparts. Thus, the mechanisms resulting in reduced hippocampal volumes seem to be related to the development of major depression.

Adult↗

PubMed2005

Code blue in the MR suite--a drill to rescue a patients with cardiac arrest from the MR scanner.

BACKGROUND: Dobutamine stress MR (DSMR) is increasingly used in the clinical routine. Due to the limitations inherent to MR, i.e. the distance of the personnel to the patient during imaging, it is necessary to set up an emergency training to rescue a patient from the scanner room in the shortest possible time. METHODS: We placed a volunteer in the 1.5 T scanner. Monitoring devices are attached in the same way as a patient would be prepared. A team of four performed the drill, everybody assigned to a certain task and position of the rescue procedure. In consecutive order, scanning was stopped, the MR table was released and the team entered the scanner room. The monitoring equipment was removed from the volunteer and he was slid onto a stretcher and moved out of the scanner room. RESULTS: The drill was performed 30 times, 3 teams were involved. The minimum time required was 32 s, maximum was 52 s. The amount of practice runs significantly reduced the rescue time. Team 1 with 15 runs had an average time of 39+/-6 s vs. team 2 with 9 runs (45+/-3 s, p<0.02) or team 3 with 6 runs (46+/-3 s, p<0.01). Team 1 practiced on three separate days each with five practice runs and consecutively improved from day one (43+/-5 s) to day three (35+/-2 s, p<0.02). CONCLUSION: A significant reduction in rescue time can be achieved with repetitive exercise. We recommend repetitive training with various scenarios, volunteers and personnel involved in the DSMR testing.

Analysis of Variance↗

PubMed2005

Ferrite-enhanced MRI monitoring in hyperthermia.

In an MRI hyperthermia hybrid system, T1 changes are investigated for monitoring thermal therapy at 0.2 T. The water bolus, which is needed for power transmission and cooling of the skin, limits MR image quality by signal compression and artifacts. Superparamagnetic ferrofluid in different concentration was investigated with MR relaxometry and MRI methods. We found that using ferrofluid in a low concentration of 70-90 ppm magnetite the water signal can be suppressed without susceptibility artifacts. With our method of signal suppression, a significant improvement of spatial and temporal resolution is possible. The ferrofluid is stable and allows RF heating at 100 MHz. This method of signal extinction may also be useful for other experimental setups where suppression of water is necessary.

Artifacts↗

PubMed2005

Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound.

OBJECTIVES: The aim of the present study was to determine the diagnostic accuracy of 64-slice computed tomography (CT) to identify and quantify atherosclerotic coronary lesions in comparison with catheter-based angiography and intravascular ultrasound (IVUS). BACKGROUND: Currently, the ability of multislice CT to quantify the degree of coronary artery stenosis and dimensions of coronary plaques has not been evaluated. METHODS: We included 59 patients scheduled for coronary angiography due to stable angina pectoris. A contrast-enhanced 64-slice CT (Senation 64, Siemens Medical Solutions, Forchheim, Germany) was performed before the invasive angiogram. In a subset of 18 patients, IVUS of 32 vessels was part of the catheterization procedure. RESULTS: In 55 of 59 patients, 64-slice CT enabled the visualization of the entire coronary tree with diagnostic image quality (American Heart Association 15-segment model). The overall correlation between the degree of stenosis detected by quantitative coronary angiography compared with 64-slice CT was r = 0.54. Sensitivity for the detection of stenosis <50%, stenosis >50%, and stenosis >75% was 79%, 73%, and 80%, respectively, and specificity was 97%. In comparison with IVUS, 46 of 55 (84%) lesions were identified correctly. The mean plaque areas and the percentage of vessel obstruction measured by IVUS and 64-slice CT were 8.1 mm2 versus 7.3 mm2 (p < 0.03, r = 0.73) and 50.4% versus 41.1% (p < 0.001, r = 0.61), respectively. CONCLUSIONS: Contrast-enhanced 64-slice CT is a clinically robust modality that allows the identification of proximal coronary lesions with excellent accuracy. Measurements of plaque and lumen areas derived by CT correlated well with IVUS. A major limitation is the insufficient ability of CT to exactly quantify the degree of stenosis.

Aged↗

PubMed2005

Reproducibility of image interpretation in MRI of the prostate: application of the sextant framework by two different radiologists.

The aim of this study was to reproduce prostate cancer (PCA) localization by MRI based on prostatic sextants (right and left base, middle, and apex) with minimal systematic error. Combined endorectal/body-phased-array-coil MRI of the prostate at 1.5 T was retrospectively evaluated twice, with an interval of more than 1 month, by each of two independent radiologists (R1 readings R11 and R12, and R2 readings R21 and R22) in 23 patients (age 51-75 years) who had radical prostatectomy within 1 month of MRI. PCA stage was pT2 in 14 patients, and pT3 in nine. Median Gleason score was 7 (range 5-9). Histopathology showed 83 sextants with PCA and 55 without. Reproducibility of sextant positions was within one MRI slice (3 mm) in over 80% of cases. For PCA localization, ROC analysis (AUC=0.584+/-0.048-0.724+/-0.043) yielded no significant intra-reader differences. R11 and R21 differed slightly (P=0.035). Intra-observer agreement (kappa=0.52-0.58) exceeded inter-observer agreement (kappa=0.35-0.45). Intra-observer Spearman correlation (r=0.72-0.74) exceeded inter-observer correlation (r=0.43-0.51) for sextants with PCA, but not for sextants without (r=0.69-0.74). Per-sextant localization and reporting provides a highly reliable framework in MRI of the prostate. MRI of the prostate should be followed up by the same radiologists to minimize systematic error of interpretation.

Aged↗