COMPARISON OF 1.0-PITCH, 1.5-PITCH, AND 2.0-PITCH ABDOMINAL HELICAL COMPUTED-TOMOGRAPHY IN EVALUATION OF NORMAL STRUCTURES AND PATHOLOGICALLESIONS

RATIONALE AND OBJECTIVES. The authors performed a comprehensive prospe ctive clinical trial comparing 1.0-, 1.5-, and 2.0-pitch abdominal hel ical computed tomography (CT) in the evaluation of normal and patholog ic structures/lesions. METHODS. Seventy-five consecutive patients were randomized by computer into one of three equal groups: helical CT pit ch 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, pla ced into a randomized order, and evaluated by five separate experience d 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 stati stical differences in 1.0- and 1.5-pitch abdominal CT scans when asses sing the display of normal and pathologic lesions. In addition, helica l pitch 1.0 and 1.5 studies were equivalent for both normal and pathol ogic structures/lesions, whereas equivalency was not demonstrated far helical pitch 2.0 studies. Overall study assessment questions again fo und equivalency between helical 1.0- and 1.5-pitch studies. CONCLUSION S. 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 e valuate the usefulness of the helical 20-pitch technique.