MDCT in suspected lumbar spine fracture: comparison of standard and reduced dose settings using iterative reconstruction.

AIM: To compare standard (SD-) and reduced-dose computed tomography (RD-CT) in combination with iterative reconstruction (IR) in emergency patients with suspected lumbar spine fracture. MATERIAL AND METHODS: Forty emergency patients with suspected lumbar spinal disorder who underwent RD-CT and 40 body mass index-matched patients undergoing SD-CT were enrolled in this retrospective study. Raw data for RD-CT were reconstructed using two increasing IR levels (IRL) 4 and 6, while SD-CT was reconstructed with IRL3. Two radiologists assessed image quality, image noise, and reader confidence in interpreting findings of spinal fractures in a blinded manner. RESULTS: Effective radiation dose was reduced by 50% using RD-CT. Overall subjective image quality (SIQ) was high for both protocols and slightly superior in the RD-CT protocol for both IRL compared to SD-CT. The detection rate of spinal disorders was high for both protocols with a high interobserver agreement. CONCLUSION: RD-CT with higher levels of IR results in substantial dose reduction of 50% in lumbar spine CT while maintaining an excellent subjective image quality resulting in a high diagnostic confidence.

Comparison of T2* relaxation times of articular cartilage of the knee in elite professional football players and age-and BMI-matched amateur athletes.

OBJECTIVE: Recent investigation has underlined the potential of quantitative MR imaging to be used as a complementary tool for the diagnosis of cartilage degeneration at an early state. The presented study analyses T2* relaxation times of articular cartilage of the knee in professional athletes and compares the results to age- and BMI (Body Mass Index)-matched healthy amateur athletes. MATERIALS AND METHODS: 22 professional football players and 22 age- and BMI-matched individuals were underwent knee Magnetic Resonance Imaging (MRI) at 3T including qualitative and quantitative analysis. Qualitative analysis included e.g. meniscal tears, joint effusion and bone edema. For quantitative analysis T2* (22 ET: 4.6-53.6ms) measurements in 3D data acquisition were performed. Deep and superficial layers of 22 predefined cartilage segments were analysed. All data sets were postprocessed using a dedicated software tool. Statistical analysis included Student t-test, confidence intervals and a random effects model. RESULTS: In both groups, T2* relaxation times were significantly higher in the superficial compared to the deep layers (p<0.001). Professional athletes had significantly higher relaxation times in eight superficial and three deep cartilage layers in the predefined cartilage segments (p<0.05). Highly significant differences were found in the weight-bearing segments of the lateral superficial femoral condyle (p<0.001). CONCLUSION: Elevated T2* values in cartilage layers of professional football players compared to amateur athletes were noted. The effects seem to predominate in superficial cartilage layers.

Accuracy of Coronary Plaque Detection and Assessment of Interobserver Agreement for Plaque Quantification Using Automatic Coronary Plaque Analysis Software on Coronary CT Angiography.

PURPOSE: To evaluate the accuracy of automatic plaque detection and the interobserver agreement of automatic versus manually adjusted quantification of coronary plaques on coronary CT angiography (cCTA) using commercially available software. MATERIALS AND METHODS: 10 cCTA datasets were evaluated using plaque software. First, the automatically detected plaques were verified. Second, two observers independently performed plaque quantification without revising the automatically constructed plaque contours (automatic approach). Then, each observer adjusted the plaque contours according to plaque delineation (adjusted approach). The interobserver agreement of both approaches was analyzed. RESULTS: 32 of 114 automatically identified findings were true-positive plaques, while 82 (72 %) were false-positive. 20 of 52 plaques (38 %) were missed by the software (false-negative). The automatic approach provided good interobserver agreement with relative differences of 0.9 ±â€Š16.0 % for plaque area and -3.3 ±â€Š33.8 % for plaque volume. Both observers independently adjusted all contours because they did not represent the plaque delineation. Interobserver agreement decreased for the adjusted approach with relative differences of 25.0 ±â€Š24.8 % for plaque area and 20.0 ±â€Š40.4 % for plaque volume. CONCLUSION: The automatic plaque analysis software is of limited value due to high numbers of false-positive and false-negative plaque findings. The automatic approach was reproducible but it necessitated adjustment of all constructed plaque contours resulting in deterioration of the interobserver agreement. KEY POINTS: • Automatic plaque detection is limited due to high false-positive and false-negative findings.• Automatic plaque quantification was reproducible in the few accurately detected plaques.• The automatically constructed contours did not represent the plaque delineation.• Both observers independently adjusted the plaque contours.• Manual adjustment of plaque contours reduced the interobserver agreement. Citation Format: • Laqmani A, Klink T, Quitzke M et al. Accuracy of Coronary Plaque Detection and Assessment of Interobserver Agreement for Plaque Quantification Using Automatic Coronary Plaque Analysis Software on Coronary CT Angiography. Fortschr Röntgenstr 2016; 188: 933 - 939.

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.

Intraindividual evaluation of the influence of iterative reconstruction and filter kernel on subjective and objective image quality in computed tomography of the brain.

OBJECTIVES: To intraindividually evaluate the potential of 4th generation iterative reconstruction (IR) on brain CT with regard to subjective and objective image quality. METHODS: 31 consecutive raw data sets of clinical routine native sequential brain CT scans were reconstructed with IR level 0 (= filtered back projection), 1, 3 and 4; 3 different brain filter kernels (smooth/standard/sharp) were applied respectively. Five independent radiologists with different levels of experience performed subjective image rating. Detailed ROI analysis of image contrast and noise was performed. Statistical analysis was carried out by applying a random intercept model. RESULTS: Subjective scores for the smooth and the standard kernels were best at low IR levels, but both, in particular the smooth kernel, scored inferior with an increasing IR level. The sharp kernel scored lowest at IR 0, while the scores substantially increased at high IR levels, reaching significantly best scores at IR 4. Objective measurements revealed an overall increase in contrast-to-noise ratio at higher IR levels, which was highest when applying the soft filter kernel. The absolute grey-white contrast decreased with an increasing IR level and was highest when applying the sharp filter kernel. All subjective effects were independent of the raters' experience and the patients' age and sex. CONCLUSION: Different combinations of IR level and filter kernel substantially influence subjective and objective image quality of brain CT.

Impact of a 4th generation iterative reconstruction technique on image quality in low-dose computed tomography of the chest in immunocompromised patients.

PURPOSE: To determine the image quality of an iterative reconstruction (IR) technique in low-dose MDCT (LDCT) of the chest of immunocompromised patients in an intraindividual comparison to filtered back projection (FBP) and to evaluate the dose reduction capability. MATERIALS AND METHODS: 30 chest LDCT scans were performed in immunocompromised patients (Brilliance iCT; 20-40 mAs; mean CTDIvol: 1.7 mGy). The raw data were reconstructed using FBP and the IR technique (iDose4™, Philips, Best, The Netherlands) set to seven iteration levels. 30 routine-dose MDCT (RDCT) reconstructed with FBP served as controls (mean exposure: 116 mAs; mean CDTIvol: 7.6 mGy). Three blinded radiologists scored subjective image quality and lesion conspicuity. Quantitative parameters including CT attenuation and objective image noise (OIN) were determined. RESULTS: In LDCT high iDose4™ levels lead to a significant decrease in OIN (FBP vs. iDose7: subscapular muscle 139.4 vs. 40.6 HU). The high iDose4™ levels provided significant improvements in image quality and artifact and noise reduction compared to LDCT FBP images. The conspicuity of subtle lesions was limited in LDCT FBP images. It significantly improved with high iDose4™ levels (> iDose4). LDCT with iDose4™ level 6 was determined to be of equivalent image quality as RDCT with FBP. CONCLUSION: iDose4™ substantially improves image quality and lesion conspicuity and reduces noise in low-dose chest CT. Compared to RDCT, high iDose4™ levels provide equivalent image quality in LDCT, hence suggesting a potential dose reduction of almost 80%.

Pulmonary manifestation of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients: initial findings with multidetector computed tomography.

OBJECTIVE: To describe initial multidetector computed tomographic (MDCT) findings of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients and to evaluate whether or not identification of certain abnormalities can help predict patients who are at risk for a severe clinical course. SUBJECTS AND METHODS: This retrospective study included 13 patients with confirmed S-OIV infection suffering from an underlying immunodeficiency or who were receiving immunosuppressive therapy. All patients underwent MDCT of the thorax due to respiratory distress. All data were read by two independent radiologists who described the type and pattern of opacities, distribution and extent of the abnormalities observed. Adverse outcome measures were defined as acute respiratory distress syndrome with the need for mechanical ventilation, extracorporeal membrane oxygenation or death. RESULTS: MDCT revealed pulmonary manifestations in 12 (92%) of 13 individuals. Six (50%) patients showed an adverse outcome with development of acute respiratory distress syndrome, 4 of these died. The most common findings were ground-glass opacities (10/12; 83%) and pulmonary consolidation (7/12; 58%) predominantly with a bilateral distribution. Reticular pattern and a tree-in-bud appearance were found in 3/12 (25%), respectively. Bilateral opacities with extensive involvement of the lung parenchyma were most predictive of a severe clinical course. CONCLUSION: The MDCT scan in immunocompromised patients with confirmed S-OIV infection frequently revealed pulmonary abnormalities, which included ground-glass opacities and consolidations. Therefore, prediction of an adverse clinical outcome could be made in patients with MDCT findings demonstrating bilateral extensive consolidations, often combined with ground-glass opacities.

Diffusion weighted MRI and 18F-FDG PET/CT in non-small cell lung cancer (NSCLC): does the apparent diffusion coefficient (ADC) correlate with tracer uptake (SUV)?

INTRODUCTION: To investigate the potential correlation of the apparent diffusion coefficient assessed by diffusion-weighted MRI (DWI) and glucose metabolism determined by the standardized uptake value (SUV) at 18F-FDG PET/CT in non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: 18F-FDG PET/CT and DWI (TR/TE, 2000/66 ms; b-values, 0 and 500 s/mm(2)) were performed in 41 consecutive patients with histologically verified NSCLC. Analysing the PET-CT data calculation of the mean (SUV(mean)) and maximum (SUV(max)) SUV was performed. By placing a region-of-interest (ROI) encovering the entire tumor mean (ADC(mean)) and minimum ADC (ADC(min)) were determined by two independent radiologists. Results of 18F-FDG PET-CT and DWI were compared on a per-patient basis. For statistical analysis Pearson's correlation coefficient, Bland-Altman and regression analysis were assessed. RESULTS: Data analysis revealed a significant inverse correlation of the ADC(min) and SUV(max) (r=-0.46; p=0.032). Testing the correlation of the ADC(min) and SUV(max) for each histological subtype separately revealed that the inverse correlation was good for both adenocarcinomas (r=-0.47; p=0.03) and squamouscell carcinomas (r=-0.71; p=0.002), respectively. No significant correlation was found for the comparison of ADC(min) and SUV(mean) (r=-0.29; p=0.27), ADC(mean) vs. SUV(mean) (r=-0.28; p=0.31) or ADC(mean) vs. SUV(max) (r=-0.33; p=0.23). The κ-value of 0.88 indicated a good agreement between both observers. CONCLUSION: This preliminary study is the first to verify the relation between the SUV and the ADC in NSCLC. The significant inverse correlation of these two quantitative imaging approaches points out the association of metabolic activity and tumor cellularity. Therefore, DWI with ADC measurement might represent a new prognostic marker in NSCLC.