Utility of low mA 1.5 pitch helical versus conventional high mA abdominal CT.

The objective of this study was to evaluate the utility of a low mA 1.5 pitch helical versus conventional high mA conventional technique in abdominal computed tomography (CT). Twenty-five patients who had both a conventional high mA (> 300) and a 1.5 pitch low mA (80-125) helical CT within 3 months were selected for inclusion in the study. Patients were excluded who had a significant change in pathology between the two studies. The other parameters (injection rate, contrast type and volume, and filming window/level) were constant. The studies were randomized and blinded to five separate experienced readers who graded the studies by a variety of normal anatomical structures and pathological criteria. Overview questions also assessed noise, resolution, contrast, and overall quality. The abdominal wall/retroperitoneum and hiatal hernias were statistically better visualized on the conventional high mA studies. However, for all other normal anatomical and pathological sites, there was equivalent or better visualization on the helical versus the conventional CT examinations. The resolution of the helical studies was graded statistically better than the high mA conventional CT scans as was the amount of noise present on the images. While there was some advantage for conventional high mA CT with respect to contrast enhancement and low contrast sensitivity, these differences were not statistically significant. It appears from the data of this study that a low mA technique in evaluating the abdomen may be a useful option in performing routine abdominal CT. The radiation dose savings to the patient is significant and there appears to be little degradation of image quality using a low mA 1.5 helical versus mA conventional CT technique.

Extended pitch thoracic helical CT 47.

The objective of this study was to test whether extended 1.5 pitch helical computed tomography (CT) can be used for routine thoracic CT without a significant loss of clinical scan quality. Thirty consecutive patients presenting for contrast thoracic CT were computer randomized into one of three groups: conventional, 1.0 pitch helical, and 1.5 pitch helical. All other variables, including kV, mA, slice thickness and reconstruction interval, and contrast administration, were kept constant. The studies were randomized to five independent, blinded, experienced radiologists who rated visualization 25 normal structures, and up to five pathologic findings per patient. In addition, each reader evaluated the studies' contrast enhancement, low contrast sensitivity, linear resolution, motion artifact, noise, and overall quality. The visualization score for all normal and overall for pathological lesions did not vary between groups. The three groups were not equivalent for several individual pathologic categories. However, these differences were not consistently in favor of one technique over the other two. The overall score for scan quality was not significantly different between the three groups. Extended 1.5 pitch thoracic helical CT provides equivalent quality versus either 1.0 pitch helical or conventional CT. The use of 1.5 pitch helical thoracic CT allows faster scanning, greater patient coverage, and the use of reduced amounts of intravenous contrast.

Comparison of 1.0-, 1.5-, and 2.0-pitch abdominal helical computed tomography in evaluation of normal structures and pathologic lesions.

RATIONALE AND OBJECTIVES: The authors performed a comprehensive prospective clinical trial comparing 1.0-, 1.5-, and 2.0-pitch abdominal helical computed tomography (CT) in the evaluation of normal and pathologic structures/lesions. METHODS: Seventy-five consecutive patients were randomized by computer into one of three equal groups: helical CT pitch 1.0, 1.5, and 2.0. The imaging parameters and contrast enhancement of all 75 patients were kept constant. The 75 studies were masked, placed into a randomized order, and evaluated by five separate experienced radiologists who rated visualization of 25 normal structures and up to five pathologic findings per patient using a scale of 1 (not seen) to 5 (very well seen/very sharp margins). RESULTS: There were no statistical differences in 1.0- and 1.5-pitch abdominal CT scans when assessing the display of normal and pathologic lesions. In addition, helical pitch 1.0 and 1.5 studies were equivalent for both normal and pathologic structures/lesions, whereas equivalency was not demonstrated for helical pitch 2.0 studies. Overall study assessment questions again found equivalency between helical 1.0- and 1.5-pitch studies. CONCLUSIONS: Abdominal CT performed with pitches of 1.0 and 1.5 are equivalent. Because of its advantages, we advocate the routine use of an extended pitch (1.5) in routine abdominal CT. Further studies are required to evaluate the usefulness of the helical 2.0-pitch technique.

Multiplanar image reconstruction and 3D imaging using a musculoskeletal phantom: conventional versus helical CT.

PURPOSE: Our goal was to perform a detailed comparison of the relative performances of helical CT (pitches 1.0, 1.5, and 2.0) and conventional (overlapped and nonoverlapped) CT in detailed 3D and MPR musculoskeletal imaging. METHOD: A specially designed bone fragment phantom was imaged with multiple slice thicknesses using conventional (overlapped and nonoverlapped) and helical (varying pitch and slice index) CT. Studies were randomized, blinded, and graded using predetermined criteria by 10 radiologists. Statistical analysis included an assessment of raw image scores, a separate testing using duplicate copies of the conventional images as gold standards, and a multivariate model based upon the results of both scoring systems. RESULTS: When assessing raw scores of the images, conventional scans were consistently scored more favorably than helical studies. Decreasing the slice index improved conventional CT studies and helical studies with a pitch of 1.0, but showed no effect on helical studies with a pitch of > 1.0. When using the conventional studies as gold standards, the helical studies were consistently graded as poorer than conventional overlapped and nonoverlapped studies. CONCLUSION: For detailed musculoskeletal 3D and MPR work, helical CT may not adequately compare with conventional CT and offers no discernible advantage, particularly for pitches of > 1.0.

Routine use of a higher order interpolator and bone algorithm in thoracic CT.

OBJECTIVE: This study was designed to evaluate the utility of the routine use of high spatial frequency algorithms and higher order helical interpolators for imaging lung parenchyma during routine thoracic CT. SUBJECTS AND METHODS: We evaluated 50 consecutive patients undergoing clinically indicated thoracic CT using the same imaging parameters and scanner. The helical volume was reconstructed three separate times using standard and higher order (180 degrees linear with double-sided lobes) interpolators and standard and high spatial frequency (bone) algorithms. The images were photographed and given to five separate readers who were kept unaware of the interpolator and algorithm and who were asked to evaluate simultaneously each patient's three sets of images for best, in-between, and worst images of the lung interstitium, pathology, and normal anatomy. RESULTS: All five readers rated the standard interpolator and algorithm images as the worst (p < .01). All five readers consistently rated the double-sided lobe interpolator and bone algorithm images as the best (p < .01). CONCLUSION: A second reconstruction of routine thoracic helical CT data using higher order helical interpolators and a bone algorithm significantly improves interstitial detail of lung parenchyma and overall visualization of normal anatomy and pathologic processes.

[Role of echography in the diagnosis of visceral ischemic syndrome]. / Ruolo dell'ecografia nella diagnosi della sindrome ischemica viscerale.

Personal experience of the current possibilities of ultrasonography in the diagnosis of visceral ischaemic syndrome is reported.

[Intramural diverticulosis of the gallbladder]. / Le diverticolosi intramurali della colecisti.

The authors report on 9 cases of acalculous adenomyomatosis of the gallbladder, selected to Arianoff's classification. The clinical, anatomopathological and radiological data are considered: there isn't difference concerning the clinical symptoms between adenomyomatosis and cholelithiasis; only radiological study may clarify the nature and character of these lesions. The authors conclude stressing the importance of surgical therapy because the medical therapy is only symptomatic and does not modify the natural evolution of the disease and its complications.