Gregor Pache

Whole-body MRI in the detection of bone marrow infiltration in patients with plasma cell neoplasms in comparison to the radiological skeletal survey

To compare the diagnostic value of whole-body MRI versus radiological skeletal survey (RSS) in staging patients with plasma cell neoplasms (PCN) and to evaluate the possible therapeutic impact of the replacement of RSS by whole-body MRI. Fifty-four patients with PCN [multiple myeloma (MM), n=47; monoclonal gammopathy of unknown significance (MGUS), n=7] were studied by whole-body MRI and RSS in a monocenter prospective analysis from August 2002 to May 2004. The MRIs were performed using a rolling table platform “AngioSURF” for unlimited field of view with a 1.5-T system (Magnetom Sonata/Maestro Class, Siemens Medical Solutions, Erlangen, Germany). A coronal STIR sequence (TR5500-4230/TE102-94/TI160) was used for imaging of the different body regions, including the head, neck, thorax, abdomen, pelvis and upper and lower extremities. The RSS consisted of eight different projections of the axial and appendicular skeleton. In 41/54 (74%) patients, the results of the whole-body MRI and RSS were concordant. In 11/54 (20%) patients, both imaging techniques were negative. Bone involvement was observed in 30/54 (55%) patients; however, whole-body MRI revealed this more extensively than the RSS in 27/30 (90%) patients with concordant positive imaging findings. In 3/30 (10%) patients, both imaging techniques demonstrated a similar extent of bone marrow infiltration. In 10/54 (19%) patients, the whole-body MRI was superior to RSS in detecting bone marrow infiltration, whereas the RSS was negative. In 3/54 (6%) patients, the RSS was proven to be false positive by the clinical course, whereas the whole-body MRI was truly negative. Whole-body MRI is a fast and highly effective method for staging PCN patients by the use of a rolling table platform. Moreover, it is more sensitive and specific than RSS and reveals bone marrow infiltration and extensive disease more reliably. Therefore, whole-body MRI should be performed as an additional method of exactly staging PCN patients and - with more data in the field - may even prove to be an alternate and more sensitive staging procedure than RSS in PCN patients.

Dual-Energy CT Virtual Noncalcium Technique: Detecting Posttraumatic Bone Marrow Lesions—Feasibility Study

PURPOSE To evaluate traumatized bone marrow with a dual-energy (DE) computed tomographic (CT) virtual noncalcium technique. MATERIALS AND METHODS In this prospective institutional review board-approved study, 21 patients with an acute knee trauma underwent DE CT and magnetic resonance (MR) imaging. A software application was used to virtually subtract calcium from the images. Presence of fractures was noted, and presence of bone bruise was rated on a four-point scale for six femoral and tibial regions by two radiologists. CT numbers were obtained in the same regions. Consensus reading of independently read MR images served as the reference standard. Image ratings and CT numbers were subjected to receiver operating characteristic curve analysis. RESULTS After exclusion of 16 regions owing to artifacts, MR imaging revealed 59 bone bruises in the remaining 236 regions (19 of 114 femoral, 40 of 122 tibial). Fractures were present in eight patients. Visual rating revealed areas under the curve of 0.886 and 0.897 in the femur and 0.974 and 0.953 in the tibia for observers 1 and 2, respectively. For CT numbers, the respective areas under the curve were 0.922 and 0.974. If scores of 1 and 2 (strong or mild bone bruise) were counted as positive, sensitivities were 86.4% and 86.4% and specificities were 94.4% and 95.5% for observers 1 and 2, respectively. The kappa statistic demonstrated good to excellent agreement (femur, kappa = 0.78; tibia, kappa = 0.87). CONCLUSION This DE CT virtual noncalcium technique can subtract calcium from cancellous bone, allowing bone marrow assessment and potentially making posttraumatic bone bruises of the knee detectable with CT.

Prosthesis Oversizing in Balloon-Expandable Transcatheter Aortic Valve Implantation Is Associated With Contained Rupture of the Aortic Root

Background— To retrospectively investigate the potential cause of contained rupture of the aortic root in balloon-expandable transcatheter aortic valve implantation (TAVI) by means of pre- and postinterventional multislice computed tomography. Methods and Results— Seventy-two patients (mean age 82±7 years, mean aortic valve area 0.69±0.19 cm2) underwent balloon-expandable TAVI using the EdwardsSAPIEN Transcatheter Heart Valve (23 mm, n=19; 26 mm, n=50; 29 mm, n=3). Aortic annulus dimensions were quantified by multislice computed tomography–based cross-sectional area assessment and average diameter calculation (CAAD) before and after TAVI. Post-TAVI multislice computed tomography data sets were available in 65 patients; contained aortic root rupture was diagnosed in 3 patients. Pre-TAVI CAAD was 23.1±1.8 mm; post-TAVI CAAD was 22.9±1.3 mm. Median relative change in CAAD pre- and post-TAVI was −0.5% (interquartile range, 3.6%). Relative increase of 5% to 10% was observed in 4 patients (1 with contained rupture), relative increase >10% in 2 patients, both with contained rupture. Mean relative oversizing, calculated as the relative difference in diameter between pre-TAVI CAAD and nominal diameter of the selected prosthesis, was 9.8%±7.8%. Relative oversizing was significantly higher in patients with contained rupture compared with patients without contained rupture (24.6%±5.4% versus 9.1%±6.6%; P<0.001). Relative oversizing ≥20% occurred in 6 patients (3 with contained rupture). Conclusions— Contained rupture of the aortic root in balloon-expandable TAVI is associated with severe prosthesis oversizing. Multislice computed tomography–based assessment of aortic annulus dimension in conjunction with adapted sizing guidelines may reduce the incidence of severe oversizing.

Early hypo-attenuated leaflet thickening in balloon-expandable transcatheter aortic heart valves

AIMS We sought to evaluate the frequency of early hypo-attenuated leaflet thickening (HALT) of the SAPIEN 3 transcatheter aortic valve (S3). METHODS AND RESULTS Of 249 patients who had undergone S3 implantation, we studied 156 consecutive patients (85 women, median age 82.2 ± 5.5 years) by electrocardiogram (ECG)-triggered dual-source computed tomography angiography (CTA) after a median of 5 days post-transcatheter aortic valve implantation. The prosthesis was assessed for HALT. Apart from heparin, peri-interventional antithrombotic therapy consisted of single- (aspirin 29%) or dual- (aspirin plus clopidogrel 71%) antiplatelet therapy. Hypo-attenuated leaflet thickening was found in 16 patients [10.3% (95% confidence interval (CI) 5.5-15.0%)] of the patients. None of the baseline and procedural variables were significantly associated with HALT, nor did we find a significant association with the antithrombotic regimen, either peri-interventionally or at the time of CTA. Hypo-attenuated leaflet thickening was found in 6 of 45 patients with peri-interventional single-antiplatelet therapy and in 10 of 111 patients with dual-antiplatelet therapy at the time of intervention [13.3% (95% CI 3.4-23.3%) vs. 9% (95% CI 3.7-14.3%), P = 0.42]. Hypo-attenuated leaflet thickening was not associated with clinical symptoms, but a small, albeit significant difference in mean pressure gradient at the time of CTA (11.6 ± 3.4 vs. 14.9 ± 5.3 mmHg, P = 0.026). Full anticoagulation led to almost complete resolution of HALT in 13 patients with follow-up CTA. CONCLUSION Irrespective of the antiplatelet regimen, early HALT occurred in 10% of our patients undergoing transcatheter aortic S3 implantation. Early HALT is clinically inapparent and reversible by full anticoagulation.

Assessment of aortic annulus dimensions for Edwards SAPIEN Transapical Heart Valve implantation by computed tomography: calculating average diameter using a virtual ring method

OBJECTIVE Accurate preoperative assessment of the aortic annulus dimensions is critical in patients undergoing transcatheter aortic valve implantation (TAVI) for severe AS. Using multislice computed tomography (MSCT), we evaluated a novel approach to quantify aortic annulus dimensions using cross-sectional area (CSA) assessment and average diameter calculation compared with the commonly applied electronic caliper measurements in patients undergoing transapical implantation of the Edwards SAPIEN Transcatheter Heart Valve. METHODS Seventy-one patients underwent pre-TAVI MSCT with the following dimensions assessed at the level of the most basal attachment points of all three aortic cusps joined by a virtual ring: CSA, calculated average annulus diameter (CAAD), and minimal, maximum, sagittal and coronal diameters. Measurements were compared with post-TAVI MSCT data sets at the level of the ventricular stent ending in 24 patients. Pre-TAVI measurements were compared to those taken post-TAVI. Eligibility to balloon-expandable TAVI was evaluated based on the different measurements. RESULTS The Edwards SAPIEN valve (23 mm, n=8; 26 mm, n=16) was implanted 2.1±1.1 mm below the non-coronary sinus. Pre-TAVI CAAD was 23.0±1.6 mm; post-TAVI CAAD was 23.0±1.1 mm. Post-TAVI CSA was circular in 18 patients (75%) and ovoid in six (25%). Pre- and post-TAVI assessment showed strong correlation for CSA and CAAD (r=0.835, p<0.001; r=0.841, p<0.001, respectively). Minimal, maximum, coronal and sagittal dimension correlated weakly between pre- and post-TAVI measurements (r=0.435-0.632, p=0.001-0.034). CONCLUSION Pre-TAVI CSA assessment and average diameter calculation using a virtual ring method is able to predict the post-interventional configuration of the annulus after balloon-expandable TAVI. We regard this approach as the best-available method to select the appropriate prosthesis size for balloon-expandable TAVI. Specific MSCT-based sizing recommendations should be developed.

Conformational Pulsatile Changes of the Aortic Annulus: Impact on Prosthesis Sizing by Computed Tomography for Transcatheter Aortic Valve Replacement

OBJECTIVES This study sought to investigate pulsatile changes of the aortic annulus and their impact on prosthesis selection by computed tomography (CT). BACKGROUND Precise noninvasive prosthesis sizing is a prerequisite for transcatheter aortic valve replacement. METHODS A total of 110 patients with severe aortic stenosis (mean age: 82.9 ± 8 years, mean aortic valve area: 0.69 ± 0.18 cm(2)) underwent electrocardiogram-gated CT. Aortic annulus dimensions were planimetrically quantified as area-derived diameter (D(A) = 2 ×✓(CSA/π), where CSA is the cross-sectional area) and perimeter-derived diameter (D(P) = P/π, where P is the length of the perimeter) in 5% increments of the RR interval. Hypothetical prosthesis sizing was based on D(A) and D(P) (23-mm prosthesis for <22 mm; 26 mm: 22 to 25 mm; 29 mm: >25 mm) and compared between maximum and traditional cardiac CT reconstruction phases at 35% and 75% of RR. Agreement for prosthesis selection was calculated by κ statistics. RESULTS D(A) and D(P) were increased and eccentricity was reduced during systole, with D(A-MAX) and D(P-MAX) most often observed at 20% of RR. D(P) was consistently larger than D(A). Average net differences were 2.0 ± 0.6 mm and 1.7 ± 0.5 mm by D(A-MIN) versus D(A-MAX) and D(P-MIN) versus D(P-MAX). Agreement for prosthesis sizing was found in 93 of 110 patients (κ = 0.75) by D(A-75%) and in 80 of 110 patients (κ = 0.53) by D(A-MAX) compared with D(A-35%); and in 94 of 110 patients (κ = 0.73) by D(P-75%) and in 93 of 110 patients (κ = 0.73) by D(P-MAX) compared with D(P-35%). With sizing by D(A-75%) or D(P-75%), nominal prosthesis diameter was smaller than D(A-MAX) or D(P-MAX) in 15 and 6 patients respectively. CONCLUSIONS Aortic annulus morphology exhibits conformational pulsatile changes throughout the cardiac cycle due to deformation and stretch. These changes affect prosthesis selection. Prosthesis selection by diastolic perimeter- or area-derived dimensions harbors the risk of undersizing.

Prospective electrocardiography-triggered CT angiography of the great thoracic vessels in infants and toddlers with congenital heart disease: Feasibility and image quality

PURPOSE To investigate feasibility and image quality and to calculate radiation dose estimates for computed tomography angiography (CTA) of the great thoracic vessels in infants and toddlers with congenital heart disease (CHD) using end-systolic prospective electrocardiography-triggered sequential dual-source data acquisition. METHODS This study was institutional review board approved; informed consent was obtained. Twenty children (age 1.2±1.1 years) underwent 22 prospective ECG-triggered sequential dual-source CTA examinations (Somatom Definition, Siemens) with tube current (250 mAs/rot) centered at 250 ms past the R-peak in the cardiac cycle (end-systole). Tube voltage was set to 80 kV. Image quality was evaluated by two readers independently using a four-point grading scale (4=excellent, 1=non-diagnostic). Radiation dose estimates were calculated from the dose-length-product (DLP). RESULTS All CT images showed diagnostic image quality (mean score 3.67±0.67, κ=0.85). Stair-step artifacts were present in one and breathing artifacts in 4 patients, with neither impairing diagnostic image quality. Mean heart rate (bpm) was 107.6±12.1 (76-130), mean heart rate variability (bpm) was 2.5±2.0 (1-9). Mean scan length (mm) was 90.7±22.7 (50-134). Mean estimated effective dose was 0.32±0.11 mSv. CONCLUSION Prospective ECG-triggered sequential dual source CTA is feasible in infants and toddlers with CHD, thereby allowing almost motion-free imaging of the great thoracic vessels with the benefit of a low radiation dose.

Reducing the radiation dose for low-dose CT of the paranasal sinuses using iterative reconstruction: Feasibility and image quality

PURPOSE To evaluate image quality of dose-reduced CT of the paranasal-sinus using an iterative reconstruction technique. METHODS In this study 80 patients (mean age: 46.9±18 years) underwent CT of the paranasalsinus (Siemens Definition, Forchheim, Germany), with either standard settings (A: 120 kV, 60 mAs) reconstructed with conventional filtered back projection (FBP) or with tube current-time product lowering of 20%, 40% and 60% (B: 48 mAs, C: 36 mAs and D: 24 mAs) using iterative reconstruction (n=20 each). Subjective image quality was independently assessed by four blinded observers using a semiquantitative five-point grading scale (1=poor, 5=excellent). Effective dose was calculated from the dose-length product. Mann-Whitney-U-test was used for statistical analysis. RESULTS Mean effective dose was 0.28±0.03 mSv(A), 0.23±0.02 mSv(B), 0.17±0.02 mSv(C) and 0.11±0.01 mSv(D) resulting in a maximum dose reduction of 60% with iterative reconstruction technique as compared to the standard low-dose CT. Best image quality was observed at 48 mAs (mean 4.8; p<0.05), whereas standard low-dose CT (A) and maximum dose reduced scans (D) showed no significant difference in subjective image quality (mean 4.37 (A) and 4.31 (B); p=0.72). Interobserver agreement was excellent (κ values 0.79-0.93). CONCLUSION As compared to filtered back projection, the iterative reconstruction technique allows for significant dose reduction of up to 60% for paranasal-sinus CT without impairing the diagnostic image quality.

Combined Assessment of Aortic Root Anatomy and Aortoiliac Vasculature With Dual-Source CT as a Screening Tool in Patients Evaluated for Transcatheter Aortic Valve Implantation

OBJECTIVE The objective of our study was to investigate the feasibility, image quality, and clinical implications of a combined dual-source CT angiography (CTA) protocol to assess aortic root anatomy and aortoiliac vasculature in patients with severe aortic stenosis evaluated for transcatheter aortic valve implantation. SUBJECTS AND METHODS Eighty consecutive patients (47 women and 33 men; mean age, 82.3 ± 7.8 [SD] years) with severe aortic stenosis evaluated for transcatheter aortic valve implantation underwent a combined single-dose contrast-enhanced dual-source CTA protocol (body weight < 70 kg, 110 mL of contrast medium; ≥ 70 kg, 130 mL) consisting of ECG-gated dual-source CTA of the chest with integrated cardiac CT and ungated CTA of the abdomen and pelvis. Two independent observers measured the dimensions of the aortic root and the aortoiliac vasculature and rated image quality semiquantitatively. Vessel attenuation was assessed. Amenability to transfemoral access was evaluated on the basis of vessel diameter (> 7 mm), anatomy, and the presence of vascular disease. RESULTS Image quality of the aortic root was diagnostic in all 80 patients, and image quality of the aortoiliac vasculature was diagnostic in 79 patients. Vascular attenuation was greater than 200 HU at any vessel level. The mean diameter of the aortic annulus was 24.1 ± 2.9 (SD) mm. Inter- and intraobserver correlations for aortic root and aortoiliac measurements were high (r = 0.93-0.99). Aortic root dimensions were suitable for transcatheter aortic valve implantation in 65 patients (81%). Thirty-eight patients (48%) were deemed amenable to instant transfemoral access without another vasculature intervention. CONCLUSION The dimensions of the aortic root and the aortoiliac vasculature can be assessed with a combined single-dose contrast-enhanced dual-source CTA protocol, thereby allowing determination of patient eligibility for transcatheter aortic valve implantation, prosthesis sizing, and evaluation of the access route in one examination.

Oversizing in transcatheter aortic valve replacement, a commonly used term but a poorly understood one: Dependency on definition and geometrical measurements

BACKGROUND In transcatheter aortic valve replacement, prosthesis oversizing is essential to prevent paravalvular regurgitation. However, the estimated extent of oversizing strongly depends on the measurement used for annular sizing. PURPOSE The aim was to investigate the influence of geometrical parameters for calculation of relative oversizing in transcatheter aortic valve replacement, reported as percentage in relation to the native annulus size, to standardize reporting. METHODS Electrocardiogram-gated cardiac dual-source CT data of 130 consecutive patients with severe aortic stenosis (mean age, 81 ± 8 years; 56 men; mean aortic valve area, 0.67 ± 0.18 cm2) were included. Aortic annulus dimensions were quantified by means of planimetry that yielded area and perimeter at the level of the basal attachment points of the aortic cusps during systole. Area- and perimeter-derived diameters were calculated as DA = 2 × √(A/π) and DP = P/π. Hypothetical prosthesis sizing was based on DA (23-mm prosthesis for 19-22 mm; 26-mm prosthesis for 22-25 mm; 29-mm prosthesis for 25-28 mm). Relative oversizing for hypothetical prosthesis selection was calculated as percentage in relation to the native annulus size. RESULTS Mean annulus area was 492.12 ± 94.9 mm2 and mean perimeter was 80.1 ± 7.6 mm. DP was significantly larger than DA (25.5 ± 2.4 mm vs 24.9 ± 2.4 mm; P < .001). Mean maximum diameter was 28.1 ± 3.0 mm and mean minimal diameter was 22.8 ± 2.4 mm. Calculated eccentricity index [EI = 1 - minimal diameter/maximum diameter)] was 0.19 ± 0.06. Difference between DP and DA correlated significantly with EI (r = 0.67; P < .001). Relative oversizing was 10.2% ± 3.8% and 21.6% ± 8.4% by DA and area, and 7.8% ± 3.9% by both DP and perimeter. CONCLUSION For planimetric assessment of aortic annulus dimensions with CT, the percentage oversizing calculated strongly depends on the geometrical variable used for quantifying annular dimensions. Standardized nomenclature seems warranted for comparison of future studies.