Impact of Hybrid Iterative Reconstruction on Agatston Coronary Artery Calcium Scores in Comparison to Filtered Back Projection in Native Cardiac CT.

PURPOSE: To investigate whether the effects of hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) measurements using the Agatston score lead to changes in assignment of patients to cardiovascular risk groups compared to filtered back projection (FBP). MATERIALS AND METHODS: 68 patients (mean age 61.5 years; 48 male; 20 female) underwent prospectively ECG-gated, non-enhanced, cardiac 256-MSCT for coronary calcium scoring. Scanning parameters were as follows: Tube voltage, 120 kV; Mean tube current time-product 63.67 mAs (50 - 150 mAs); collimation, 2 × 128 × 0.625 mm. Images were reconstructed with FBP and with HIR at all levels (L1 to L7). Two independent readers measured Agatston scores of all reconstructions and assigned patients to cardiovascular risk groups. Scores of HIR and FBP reconstructions were correlated (Spearman). Interobserver agreement and variability was assessed with ĸ-statistics and Bland-Altmann-Plots. RESULTS: Agatston scores of HIR reconstructions were closely correlated with FBP reconstructions (L1, R = 0.9996; L2, R = 0.9995; L3, R = 0.9991; L4, R = 0.986; L5, R = 0.9986; L6, R = 0.9987; and L7, R = 0.9986). In comparison to FBP, HIR led to reduced Agatston scores between 97 % (L1) and 87.4 % (L7) of the FBP values. Using HIR iterations L1 - L3, all patients were assigned to identical risk groups as after FPB reconstruction. In 5.4 % of patients the risk group after HIR with the maximum iteration level was different from the group after FBP reconstruction. CONCLUSION: There was an excellent correlation of Agatston scores after HIR and FBP with identical risk group assignment at levels 1 - 3 for all patients. Hence it appears that the application of HIR in routine calcium scoring does not entail any disadvantages. Thus, future studies are needed to demonstrate whether HIR is a reliable method for reducing radiation dose in coronary calcium scoring.

Immunogenicity and safety of a two-dose live attenuated varicella vaccine given to adults following autologous hematopoietic stem cell transplantation.

BACKGROUND: Immunogenicity and safety of varicella vaccine (Varilrix(™) [Oka-RIT]; GlaxoSmithKline Vaccines) in adults who had undergone autologous hematopoietic stem cell transplantation (HSCT) were assessed (September 2003 to September 2007; NCT00792623). METHODS: Two Oka-RIT doses were given at 4.5 and 6.5 months post transplantation. Humoral immune responses were assessed using an immunofluorescence assay (anti-varicella zoster virus [VZV] antibody; cutoff 1:4) after each vaccine dose. Solicited local (8 day) and general (43 day), unsolicited (until day 43) adverse events (AEs) after each vaccine dose and serious adverse events (SAEs) (until 17.5 months post dose 2) were recorded. RESULTS: Of 45 patients, 19 were included in the according to protocol cohort for immunogenicity; 15 patients had pre- and post-vaccination serum samples positive for anti-VZV antibodies. Vaccine responses (anti-VZV antibody titer ≥1:4 in seronegative patients, and ≥4-fold increase in anti-VZV antibody titer in seropositive patients) were elicited by only 2 patients 2 months post dose 1, and by a single patient 1.5 months post dose 2. Although no major safety signals were detected, any and Grade 3 solicited AEs that were causally related to vaccination were reported by 44.8% and 10.3% patients, respectively. During the 43-day follow-up period, 3 patients developed varicella-like rash (1 vaccine-type VZV). Beyond 43 days, herpes zoster was reported in 2 patients and wild-type varicella infection in 2 patients (1 was breakthrough infection). Four non-fatal SAEs were reported by patients and considered causally unrelated to vaccination. CONCLUSION: Oka-RIT was poorly immunogenic but safe when given to adults up to 6 months post autologous HSCT, and alternative strategies are required to prevent VZV-associated complications in these populations.

Effect of stem cell transplantation for B-cell malignancies on disease course of associated polyneuropathy.

B cell dyscrasias are often refractory to medical treatments, and hematological stem cell therapy (SCT) may be warranted. It is not clear whether an associated polyneuropathy may also profit from SCT. In exceptional cases SCT has been tried in patients with monoclonal gammopathy and progressive polyneuropathy refractory to medical treatments. In a cohort of 225 patients with monoclonal gammopathy and polyneuropathy, we selected the six patients who underwent SCT and retrospectively examined the effects of SCT on the disease course of the associated polyneuropathy. In all patients except one, the indication for SCT was hemato-oncological (multiple myeloma in 4 patients and primary AL amyloidosis in 1). The remaining patient had an IgG monoclonal gammopathy of undetermined significance and a progressive and painful polyneuropathy for which she was treated with SCT. SCT led to improvement of motor scores and autonomic symptoms in one patient; three patients experienced improvement of neuropathic pain or sensory deficits but showed further progression of weakness. One patient showed no improvement at all. One patient died within 100 days after SCT. In conclusion, SCT as a treatment of refractory hematological malignancy may occasionally have a positive effect on the associated progressive polyneuropathy, although the benefits are very limited and the treatment-related mortality is high.

Extreme xanthomatosis in patients with both familial hypercholesterolemia and cerebrotendinous xanthomatosis.

Two unrelated individuals were referred to Lipid Clinics in The Netherlands and Chile with extreme xanthomatosis and hypercholesterolemia. Both were diagnosed with heterozygous familial hypercholesterolemia (heFH) after molecular genetic analysis of the low-density lipoprotein (LDL) receptor gene. Since heFH by itself could not account for the massive xanthomas, the presence of an additional hereditary lipid or lipoprotein disorder was suspected. Further genetic analysis revealed homozygozity for mutations in the sterol 27-hydroxylase gene, confirming the diagnosis of cerebrotendinous xanthomatosis (CTX). Markedly, the typical neurological manifestations of CTX were absent, suggestive of a protective role of LDL-receptor deficiency against the severe neurological consequences of CTX.

Bixbyite-type V2O3--a metastable polymorph of vanadium sesquioxide.

A metastable polymorph of vanadium sesquioxide was prepared by the reaction of vanadium trifluoride with a water-saturated gaseous mixture of 10 vol % hydrogen in argon. The new polymorph crystallizes in the bixbyite-type structure. At temperatures around 823 K a transformation to the well-known corundum-type phase is observed. Quantum-chemical calculations show that the bixbyite-type structure is about 9 kJ/mol less stable than the known corundum-based one. This result, in combination with the absence of imaginary modes in the phonon density of states, supports the classification of the bixbyite-type phase as a metastable V(2)O(3) polymorph. At ~50 K a paramagnetic to canted antiferromagnetic transition is detected.

Assessment of left ventricular function parameters with a new three-dimensional shape model.

PURPOSE: To evaluate a 3D model of the left ventricle (LV) which allows calculation of LV function parameters on the basis of both short axis (SA) and long axis (LA) cine acquisitions. Comparison with the conventional Simpson's rule method in a volunteer and patient collective. MATERIALS AND METHODS: Cine imaging was performed with a prospectively triggered SSFP sequence: trueFISP: TR 3.6 msec, TE 1.8 msec, bFFE: TR 3.0 msec, TE 1.4 msec, flip angle 60 degrees , resolution 1.37 x 1.37 mm, slice thickness 8 mm, gap 2 mm in SA orientation from apex to basis and in radial LA orientation (spacing 15 degrees) in 11 volunteers and 27 patients with mitral valve insufficiency. Five different volume computations were compared: Simpson's rule based on all SA slices (M0), 3D shape model based on all SA slices (M1a), 3D shape model based on 3 SA slices (M1b), 3D shape model based on all SA and LA slices (M2a), and 3D shape model based on 3 SA slices and 1 LA slice (M2b). RESULTS: M 0 and M 1a give similar results (r: 0.99, b: 0.98). M 2a produces larger volumes than M 0 (b: 0.85) due to the inclusion of the LA contours. M 1b effectively reproduces the volumes computed with M 0 (r: 0.99, b: 1.02). M 2b effectively reproduces the volumes computed with M 2a (r: 0.99, b: 0.94). M 2b and M 0 give similar results in the patient collective (r: 0.99, b: 0.97). CONCLUSION: The proposed 3D shape model allows merging of information acquired in different orientations and thus the combination of SA and LA contours with better coverage of the left ventricle. It provides a suitable fit with a reduced number of segmented contours.

Long term results after implantation of tissue engineered cartilage for the treatment of osteochondral lesions in a minipig model.

In present study we determined the long term in vivo integration and histological modeling of an in vitro engineered cartilage construct. Tissue engineered autologous cartilagenous tissue was cultured on calcium phosphate cylinders and implanted into osteochondral defects into the femoral condyles in minipigs. Radiological follow-up was performed at 2, 8, 26 and 52 weeks, condyles were harvested 26 and 52 weeks post-implantation. Thickness of cultivated tissue (1.10 +/- 0.55 mm) was comparable to in situ cartilage and cells produced in vitro cartilage specific proteins. In vivo, 26 and 52 weeks post-implantation defects were resurfaced with hyaline-like tissue, the implants were well integrated with no gap at the interface between the engineered neocartilage and the adjacent articular cartilage. Synthesis of type II collagen was detected 26 and 52 weeks after implantation. The modified ICRS score increased from 26 to 52 weeks. Histomorphometric evaluation revealed a decrease in cellularity in tissue engineered cartilage from 2.2-fold of native cartilage after 26 weeks to 1.5-fold after 52 weeks. In conclusion, these findings demonstrate the integration and maturation of tissue engineered cartilage pellets attached on a bone substitute carrier implanted in osteochondral defects over a long time.

Assessment of functional anatomy of the mitral valve in patients with mitral regurgitation with cine magnetic resonance imaging: comparison with transesophageal echocardiography and surgical results.

The ability of magnetic resonance imaging (MRI) to accurately define the functional anatomy of mitral regurgitation was assessed. Transesophageal echocardiography (TEE) and cine MRI were performed on 43 patients with mitral regurgitation and were compared for the jet number, location, direction and presence of a prolapse (atrial displacement, malapposition or a flail). In 36 patients, diagnostic accuracy in reference to surgery was assessed. Comparing TEE and MRI the jet number and location were judged in concordance in 86% of patients. Jet location did not show a significant difference (Wilcoxon: P = 0.66) and both modalities correlated strongly (Spearman: r = 0.68, P<0.0001). Jet direction was judged with high concordance (kappa=0.63). Additionally, prolapse evaluation showed high concordance (kappa: valve, 0.63; anterior mitral leaflet, 0.70; posterior mitral leaflet, 0.73). Compared with surgery, the sensitivity for the detection of malapposition of any leaflet or one of both leaflets ranged between 75% and 93% for TEE and 71% and 89% for MRI. Specificities ranged between 88 and 96% for TEE and 88 and 100% for MRI. TEE detected torn chordae in all ten patients, six of which were missed by MRI. MRI is comparable with TEE in prolapse and jet evaluation. MRI is inferior to TEE in depicting anatomical details such as torn chordae.

[Evaluation of two "fast" software tools for the measurement of left ventricular volumes in retrospectively ECG-gated multidetector CT of the heart: biplane area-length method and "shape tracking" method]. / Evaluation von zwei "schnellen" Softwareprogrammen zur Bestimmung der linksventrikulären Volumina in der retrospektiv EKG-gegateten Mehrzeilen-Spiral-CT des Schweineherzens: Biplanare Flächen-Längen-Methode und "Shape-tracking"-Methode.

PURPOSE: Evaluation of 2 "fast" software tools, a biplane area-length method, and a new automatic "shape tracking" method, for the calculation of left ventricle volumes (end-diastolic volume EDV, end-systolic volume ESV, stroke volume SV) and ejection fraction (EF) in retrospectively ECG-gated multidetector computed tomography. MATERIALS AND METHODS: 60 contrast-enhanced cardiac CT datasets (16 x 0.75 mm collimation, normal dose: 120-140 kV, 400-500 mAs (eff) [n = 44], low dose 120 kV, 100 mAs (eff) [n = 16]) were acquired from eight intubated healthy pigs on different days. Images were reconstructed with a slice thickness and increment of 2 mm every 10 % of the cardiac cycle. The LV function was evaluated via the common short axis method as the reference method, the biplane area-length method, and the automatic "shape tracking" method. In the latter a three-dimensional triangulated deformable surface model was used to segment the endocardial border of the left ventricle and to track its motion through the cardiac phases. The results were compared using the Bland-Altman-plot, the correlation coefficient, and the Wilcoxon test. RESULTS: All 60 data sets could be evaluated with all three methods. Good correlations were found for left ventricular functional parameters for all data sets, the normal dose (ND), and low dose (LD) data sets between 0.65 and 0.89 for the "shape tracking" method and between 0.7 and 0.87 for the area-length method. The "shape tracking" method showed a mean overestimation of the EDV of 3.1 (LD, p = 0.38) to 4.3 ml (ND, p < 0.05), the SV of 4.0 (LD, p = 0.08) to 4.9 ml (ND, p < 0.05) and the EF of 1.3 (LD, p = 0.16) to 2.0 % (ND, p < 0.05). The EDV was underestimated between 0.3 (LD, p = 0.7) and 1.1 ml (ND, p = 0.08). The area-length method showed an overestimation of the EDV (6.6 to 6.7 ml [p < 0.05]), the SV (5.9 to 8.4 ml [p < 0.05]), the EF (1.2 to 3.0 % [p < 0.05]) and the normal dose ESV (0.6 ml [p = 0.74]). The low dose ESV was underestimated (1.3 ml [p = 0.21]). CONCLUSION: The left ventricular functional parameters acquired with both "fast" software methods correlate well with the common semi-automatic short axis method, and both methods significantly overestimate the EDV, SV and EF. Both methods can be used in low dose examinations.

[Patterns of delayed-enhancement in MRI of ischemic and non-ischemic cardiomyopathies]. / Muster der späten Kontrastmittelanreicherung in der MRT bei ischämischen und nicht-ischämischen Kardiomyopathien.

Contrast-enhanced MRI using the delayed-enhancement technique (DE-MRI) is widely applied in the clinical work-up of myocardial diseases. Myocardial diseases of varying etiology result in myocardial changes, such as necrosis, fibrosis, edema and metabolite deposition, which can be visualized by DE-MRI. Acute and chronic ischemic diseases based on a coronary artery disease as well as non-ischemic cardiomyopathies display DE. Cardiomyopathies often show a characteristic enhancement pattern. While ischemic lesions are localized in the subendocardium, non-ischemic cardiomyopathies often display an intramyocardial or subepicardial pattern. The typical pattern for dilated cardiomyopathies is band-like and intramyocardial with septal involvement. Arrhythmogenic right-ventricular dysplasias/cardiomyopathies are frequently associated with right-ventricular DE. In the case of amyloid cardiomyopathies which are often restrictive cardiomyopathies, subendocardial and circular DE is typically observed. Hypertrophic cardiomyopathies display patchy intramyocardial DE usually in the anteroseptal region. Acute myocarditis is typically accompanied by intramyocardial or subepicardial DE affecting the lateral wall. In the case of chronic myocarditis, intramyocardial or subepicardial DE is observed most frequently. Cardiac sarcoidosis typically entails patchy subepicardial DE with right- and left-ventricular involvement. Since there is an overlap between the enhancement patterns of cardiomyopathies, the diagnostic accuracy of DE-MRI is limited and the diagnosis must be based on additional clinical and MRI findings. The amount of DE often corresponds with cardiac functional parameters as well as with the frequency of cardiac events so that DE-MRI may be useful for risk stratification. Furthermore, DE-MRI can be helpful in the planning and evaluation of myocardial biopsies and electrophysiological examinations.

Computer-assisted analysis of 4D cardiac MR image sequences after myocardial infarction.

OBJECTIVES: Spatial-temporal MR image sequences of the heart contain information about shape and motion changes and pathological structures after myocardial infarction. In this paper a Heart Analysis Tool (HeAT) for the quantitative analysis of 4D MR image sequences of infarct patients is presented. METHODS: HeAT supports interactive segmentation of anatomical and pathological structures. Registration of Cine- and DE-MR image data is applied to enable their combined evaluation during the analysis process. Partitioning of the myocardium in segments enables the analysis with high local resolution. Corresponding segments are generated and used for inter/intrapatient comparison. Quantitative parameters were extracted and visualized. RESULTS: Parameters like endocard movement in the infarcted area of six infarct patients were computed in HeAT. Parameters in the infarct area show the expected dysfunctional characteristics. Based on theses parameters passive endocardial movement and myocardial areas with decreased contraction could be identified. CONCLUSION: In contrast to other software tools HeAT supports the combination of contour information of Cine-MR and DE-MR, local analysis with high resolution and inter/intra patient comparison. HeAT enables an observer-independent evaluation of the complex cardiac image data. Using HeAT in further studies can increase the understanding of left ventricle (LV) remodeling.

[Multislice CT urography (MSCTU): evaluation of a modified scan protocol for optimized opacification of the collecting system]. / Mehrschicht-CT-Urographie (MSCTU): Beurteilung eines modifizierten Untersuchungsprotokolls zur Optimierung der Kontrastierung des Harnwegsystems.

PURPOSE: To retrospectively quantify opacification of the urinary tract using a MSCTU protocol based on furosemide and individual adaptation of urographic acquisition delay. MATERIALS AND METHODS: MSCTU examinations obtained from 4-row and 16-row CT scanners in 53 patients (35 men, 18 women, average age 59) were independently reviewed by two radiologists. MSCTUs were performed using a low-dose injection of furosemide. No fixed scan delay for urographic image acquisition was applied. The urographic timing was individually adapted by performing low-dose test images of the distal ureters to display their current opacification. Image analysis included grading of the opacification of the segmented collecting system. The average urographic delay was calculated. Stratified comparisons of mean scores were assessed using the Friedman and Wilcoxon tests. The inter-observer kappa value was calculated. RESULTS: The calculated median scan delay for patients with normal serum-creatinine levels (n = 51) was 418 sec (mean 447 sec; SD, 118 sec). The median number of acquired test images was 2 (range 1 - 6 images). The opacification analysis demonstrated that 98 % of the ICS, 90 % of the proximal, 86 % of the middle, and 83 % of the distal ureteral segments showed opacification greater than 90 %. 9.5 % of the distal ureteral segments could not be visualized. Statistics did not show significant opacification differences between proximal, middle, and distal ureteral segments (p > 0.05). The two observers were largely in agreement (kappa coefficient r = 0.81). CONCLUSION: The analyzed MSCTU technique based on furosemide and scan delay timing by means of test images reliably lead to a homogenous opacification of the entire upper urinary tract. It features the individual adaptation of MSCTU to the excretory rate of the kidneys.

[Clinical relevance of "bone bruise" detected by MRI following spinal injuries in children]. / Zur Bedeutung der MRT-Diagnose "bone bruise"" bei kindlichen Wirbelsäulenverletzungen.

BACKGROUND: MRI is a sensitive diagnostic tool, which is especially suited for the diagnosis of vertebral injuries in children since no radiation has to be applied to gonads or blood-producing organs. An indirect sign of vertebral injury is the presence of "bone bruise," an edema of the vertebral body without other bony lesions. The purpose of this study was to elucidate the clinical significance of "bone bruise" following vertebral trauma in children. PATIENTS AND METHODS: Between 1998 and 2003 a total of 66 children with vertebral injuries were treated at our institution; 34 of these patients initially underwent MRI. In this retrospective study 20 of these children who were diagnosed with a vertebral injury based on the presence of a "bone bruise" in an MRI on admission were examined clinically as well as by follow-up MRI. RESULTS: All 20 patients stated they felt no limitations in daily activities. On examination there were no significant pathologic findings. We did not note persistence of a "bone bruise" or a collapse of the affected bone in the follow-up MRI. CONCLUSION: If a "bone bruise" is detected in the MRI after vertebral trauma in children, it usually has a good prognosis. With adequate therapy, which in our regimen consists of bedrest and early mobilization, we did not note any secondary collapse of the affected vertebrae.

[MRI of pulmonary arteries in follow-up after arterial-switch-operation (ASO) for transposition of great arteries (d-TGA)]. / MRT der Pulmonalarterien bei Kindern nach arterieller Switch-Operation (ASO) bei Transposition der grossen Gefässe (d-TGA).

PURPOSE: To determine the value of MRI in postoperative evaluation of patients with arterial-switch-operation (ASO) for d-TGA. MATERIAL AND METHODS: 14 consecutive patients with d-TGA and ASO were examined with MRI in addition to ultrasound because the acoustic window in echocardiography was insufficient. Nine patients had a pulmonary-artery-bifurcation anterior to the aortic root (group 1), and five (group 2) laterally (two of them left, three of them right). MRI was performed in six patients as contrast-enhanced MR-angiography, in 8 patients as native examination. Diameters of pulmonary arteries were measured in two perpendicular views at the origin and in two further locations each with a distance of one cm. RESULTS: One patient showed a supravalvular pulmonary artery stenosis with subsequent pulmonary artery aneurysm, which had not been detected in echocardiography. This patient showed only indirect signs of pulmonary artery stenosis in echocardiography. Compared to group 1, pulmonary arteries in group 2 generally had greater diameters. Those pulmonary arteries in Group 2 which cross the mediastinum underneath the aortic arch had lower diameters compared to the pulmonary artery positioned on the other side. In group 1, the left-sided pulmonary artery had lower diameters than the right-sided pulmonary arteries. It seems remarkable that the narrowing of pulmonary arteries is associated with a flattening of the transversal vessel diameter. CONCLUSION: Narrowing of pulmonary arteries after ASO is associated with oval vessel diameters. Therefore, multiplanar diagnostic methods are necessary. MRI meets this prerequisite and is therefore advantageous to echocardiography in follow-up examinations at patients with ASO for d-TGA. Special attention should be focused on the main pulmonary artery, on the left pulmonary artery in patients with preaortic pulmonary artery bifurcation as well as on the pulmonary artery which crosses the mediastinum in patients with laterally placed pulmonary artery bifurcation. Angiography should only be performed when intervention is planned.

Evaluation of spatial and temporal resolution for ECG-gated 16-row multidetector CT using a dynamic cardiac phantom.

Measurements of spatial and temporal resolution for ECG-gated scanning of a stationary and moving heart phantom with a 16-row MDCT were performed. A resolution phantom with cylindrical holes from 0.4 to 3.0 mm diameter was mounted to a cardiac phantom, which simulates the motion of a beating heart. Data acquisition was performed with 16x0.75 mm at various heart rates (HR, 60-120 bpm), pitches (0.15-0.30) and scanner rotation times (RT, 0.42 and 0.50 s). Raw data were reconstructed using a multi-cycle real cone-beam reconstruction algorithm at multiple phases of the RR interval. Multi-planar reformations (MPR) were generated and analyzed. Temporal resolution and cardiac cycles used for image reconstruction were calculated. In 97.2% (243/250) of data obtained with the stationary phantom, the complete row of holes with 0.6 mm was visible. These results were independent of heart rate, pitch, scanner rotation time and phase point of reconstruction. For the dynamic phantom, spatial resolution was determined during phases of minimal motion (116/250). In 40.5% (47/116), the resolution was 0.6 mm and in 37.1% (43/116) 0.7 mm. Temporal resolution varied between 63 and 205 ms, using 1.5-4.37 cardiac cycles for image reconstruction.

Evaluation of balanced steady-state free precession (TrueFISP) and K-space segmented gradient echo sequences for 3D coronary MR angiography with navigator gating at 3 Tesla.

PURPOSE: To test the feasibility of k-space segmented gradient-echo pulse sequences for free-breathing coronary magnetic resonance angiography (cMRA) on a clinical 3T system. MATERIALS AND METHODS: T2-prepared, fat-suppressed turbo field echo (TFE, turboFLASH, SFPGR) as well as balanced TFE (b-TFE, trueFISP, FIESTA, segmented SSFP) sequences with navigator gating for prospective motion correction were applied on a 3T system equipped with a six-element phased-array cardiac coil. In 15 healthy volunteers, the right coronary artery (RCA) was examined with TFE and b-TFE sequences. Due to examination time limitations, the left coronary artery (LM/LAD) was examined exclusively with the TFE sequence in ten volunteers. Image quality was graded on a five point scale (0 = not visualized to 4 = excellent). The length, diameter and sharpness of the vessels and the contrast-to-noise ratios (CNR) were measured. RESULTS: 98 % of all major segments (proximal/middle/distal) of the RCA could be seen with the TFE sequence and 82 % with the b-TFE sequence. The image quality for the three segments was graded higher for the TFE sequence (2.7/2.7/1.5) than for the b-TFE sequence (1.9/1.6/0.9) with P: (< or = 0.001/< or = 0.004/< or = 0.056). The kappa of the interobserver variability was 0.75 for the TFE sequence and 0.8 for the b-TFE sequence. The measured vessel lengths were longer for the TFE sequence (95 +/- 22 mm) than for the b-TFE sequence (80 +/- 40 mm; P < or = 0.115). No significant changes (P < or = 0.074, P < or = 0.145) in diameter and vessel sharpness of the RCAs were observed between the TFE (2.4 +/- 0.3 mm, 60 % +/- 5) and b-TFE sequences (2.4 +/- 0.3 mm, 62 % +/- 6). The CNR was higher for the TFE sequence (10.1 +/- 3.4) than for the b-TFE sequence (6.6 +/- 2.1; P < or = 0.014). All ten main and proximal segments of the LM/LAD, which were examined exclusively with the TFE sequence, were visible with grade 2.5 and 2.1. The middle segment was visible in seven cases with grade 1.3. In three cases, the distal segment was visible with grade 0.5. The vessel length was 78 +/- 27 mm and the CNR 11.9 +/- 2.4. CONCLUSION: The conventional TFE technique has demonstrated good feasibility for cMRA at 3T. In its operational availability at 3T, the b-TFE sequence is inferior to the TFE sequence.

MR elastography of the prostate: initial in-vivo application.

PURPOSE: To analyze the initial assessment of the technical feasibility of in-vivo MR elastography (MRE) of the prostate gland in healthy volunteers. MATERIALS AND METHODS: Dynamic sinusoidal MR elastography was performed in 7 healthy volunteers in prone position. The mechanical wave was induced via an external oscillator attached to the pubic bone. A 1.5 Tesla MR system (Philips Medical Systems, Netherland) was used with 4 combined surface coils for signal reception. MRE data acquisition was performed with a motion-sensitive spin-echo MR sequence that was phase-locked to the mechanical oscillation. Subsequently, these images were used to reconstruct the local distribution of elasticity inside the prostate gland. The applied reconstruction algorithm was tested by means of phantom measurements. RESULTS: Sufficient penetration of the mechanical wave into the prostate gland was achieved in all volunteers, allowing the acquisition of utilizable image data sets. The reconstructed distribution of elasticity (shear-modulus) inside the healthy prostate gland correlated with the zonal anatomy of the gland. The elasticity of the central portion (2.2 +/- 0.3 kPa) appeared to be lower than the peripheral prostatic portion (3.3 +/- 0.5 kPa). CONCLUSION: In-vivo MRE of the prostate gland is technically feasible. The proposed experimental set-up allows the efficient insertion of the mechanical wave into the prostate gland and provides a successful MR data acquisition.

[Evaluation of experimental cartilage lesions with ultrahigh-resolution multi-slice-CT in comparison to histology]. / Evaluation experimenteller Knorpeldefekte mit der ultrahochauflösenden Mehrzeilen-CT im Vergleich zur Histologie.

PURPOSE: Histologic validation of ultrahigh-resolution multi-slice (MS)-CT for the evaluation of focal, experimental cartilage lesions with special regard to the subchondral bone. Testing of micro-CT ( micro CT) as alternative reference standard. METHODS: 32 experimental cartilage lesions in bovine patellae were imaged surrounded by air (MS-CT-air) and immersed in a contrast material solution (MS-CT-CM) with MS-CT (collimation 2 x 0,5 mm). After the micro CT (8 micro m-voxelsite) examination in three specimen and histologic work-up of 29 specimen two radiologist graded the defects on MS-CT images in consensus (subchondral bone involvement yes or no) and results were compared to the results of histomorphometry and micro CT. RESULTS: The MS-CT-air and -CM had an accuracy of 94 % (30/32) and 88 % (28/32), respectively. MS-CT-air led to one false-positive (remaining cartilage: = 0,1 mm) and false-negative result, each. MS-CT-CM showed false-positive results if the remaining cartilage was < 0,3 mm thick (n = 4), i. e. showed subchondral bone involvement. Contrast-to-noise ratio was significantly higher in MS-CT-air compared to MS-CT-CM. micro CT yielded a clear depiction of cartilage defect depth in the three cases. CONCLUSION: MS-CT-air has a high accuracy in the depiction of focal cartilage defects. MS-CT-CM has a tendency to overestimate cartilage defect depth. micro CT could potentially serve as alternative reference standard to histology.