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. 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.