The American Society of Nuclear Cardiology and the Society of Nuclear Medicine conclude that incorporation of attenuation corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve diagnostic accuracy. The aim was to investigate the value of adding AC stress-only images for the decision whether a rest study is necessary or not.
1,261 patients admitted to (99m)Tc MPS were studied. The stress studies were interpreted by two physicians who judged each study as "no rest study necessary" or "rest study necessary", by evaluating NC stress-only and NC + AC stress-only images. When there was disagreement between the two physicians, a third physician evaluated the studies. Thus, agreement between 2 out of 3 physicians was evaluated.
The physicians assessed 214 more NC + AC images than NC images as "no rest study necessary" (17% of the study population). The number of no-rest-study-required was significantly higher for NC + AC studies compared to NC studies (859 vs 645 cases (p
Aim of this study was to retrospectively compare the image quality and the radiation dose of an ultra high pitch CT scan for the evaluation of pulmonary embolism and visualization of cardiac structures in comparison to our institution's standard pulmonary embolism protocol.
The study cohort consisted of 115 consecutive patients, 57 underwent CT pulmonary angiography on a dual source 128 slice scanner (Siemens Somatom Definition FLASH) via an ultra high pitch mode (Pitch 2.8) while 58 were scanned on a dual source 64 slice scanner (Siemens Somatom Definition Dual Source) with standard pitch (Pitch 0.9). Qualitative image assessment was determined by two blinded radiologists with 3 and 15 years' experience in chest and cardiac CT. Quantitative image assessment was determined by the signal to noise ratio (SNR) and contrast to noise ratio (CNR). Effective radiation dose was calculated via the product of the dose length product.
For the ultra high pitch protocol, 14% (8/57) were positive for pulmonary embolus compared to 13.7% (8/58) for the standard pitch group. 98.2% of the ultra high pitch scans were diagnostic for pulmonary embolus vs. 94.8% of the standard protocol. Visualization of cardiac structures was significantly improved with the ultra high pitch protocol (p
Subject movement during multislice interleaved MR acquisitions: prevalence and potential effect on MRI-derived brain pathology measurements and multicenter clinical trials of therapeutics for multiple sclerosis.
To show the prevalence of inter-packet motion in clinical trial magnetic resonance imaging (MRI) data and the effect of inter-packet motion on MRI-derived brain pathology measurements.
We present a method to detect and quantify inter-packet motion, apply it to 2384 MRIs to determine the prevalence of inter-packet motion in clinical trial data, and show the effect of inter-packet motion on measuring multiple sclerosis (MS) lesion volumes.
Experiments with simulated data showed that the detection procedure was accurate at measuring the amount of movement between packets and quantifying the amount of missing data. Application to clinical trial data demonstrated that a large number of MRIs had missing data due to inter-packet motion; 20% of the images had greater than 10% of the data missing and 10% of the images had greater than 15% of the data missing. These levels corresponded to thresholds where lesions were difficult to visually identify or disappeared completely. Lesion volume measurement errors ranged from 1.3 ± 0.5% to 9.9 ± 6.3%.
Inter-packet motion can introduce substantial errors to MRI-derived brain pathology measurements. The prevalence of inter-packet motion is substantial in MS clinical trial data. Automated detection procedures should be implemented to increase the fidelity of MRI-derived measurements.