Restricted CT Scans Did Not Harm Sensitivity

NEW ORLEANS — Abdominal computed tomography limited to the region of tenderness accurately delineates acute pathology while reducing radiation exposure, according to a double-blind study.

A standard abdominal CT scan covers an area from above the diaphragm to the mid-thigh. But in the study, limiting the scan to the tender area cut radiation exposure by a mean of 69% while preserving 96% sensitivity, Dr. Joshua Broder said at the annual meeting of the Society for Academic Emergency Medicine.

The 93 patients in the single-center study underwent standard abdominal CT after presenting to the emergency department with nontraumatic abdominal tenderness. Before imaging, emergency physicians placed skin markers to delineate the cephalocaudad extent of tenderness. Then they added coded meaningless markers so radiologists would remain blinded to the region of tenderness, said Dr. Broder of Duke University Medical Center, Durham, N.C.

Of the 93 patients, 51 ultimately were found to have abdominal pathology, most commonly acute appendicitis. In one-third of cases, the pathology identified by radiologists was completely contained in the area highlighted by the skin markers of abdominal tenderness; in another 51%, the pathology was partially located in the marked zone and would have been readily detected by a scan limited to the region of abdominal tenderness.

Although in 16% of cases, the pathology wasn't even partially in the skin marker zone, in most of those instances it was doubtful that the pathology actually caused the abdominal pain. The rate of clinically relevant false-negative abdominal CT scans limited to the area of pain and tenderness was only 4%.

Dr. Broder and his associates also tested intermediately restricted CT, in which the entire abdomen and pelvis below the most cephalad skin marker of tenderness was scanned. This reduced radiation exposure by 38% and increased test sensitivity to 98%.

Based on the encouraging results in a nonconsecutive series, Dr. Broder plans to perform a larger, double-blind study in a consecutive series of similar patients.

NEW ORLEANS — Abdominal computed tomography limited to the region of tenderness accurately delineates acute pathology while reducing radiation exposure, according to a double-blind study.

A standard abdominal CT scan covers an area from above the diaphragm to the mid-thigh. But in the study, limiting the scan to the tender area cut radiation exposure by a mean of 69% while preserving 96% sensitivity, Dr. Joshua Broder said at the annual meeting of the Society for Academic Emergency Medicine.

The 93 patients in the single-center study underwent standard abdominal CT after presenting to the emergency department with nontraumatic abdominal tenderness. Before imaging, emergency physicians placed skin markers to delineate the cephalocaudad extent of tenderness. Then they added coded meaningless markers so radiologists would remain blinded to the region of tenderness, said Dr. Broder of Duke University Medical Center, Durham, N.C.

Of the 93 patients, 51 ultimately were found to have abdominal pathology, most commonly acute appendicitis. In one-third of cases, the pathology identified by radiologists was completely contained in the area highlighted by the skin markers of abdominal tenderness; in another 51%, the pathology was partially located in the marked zone and would have been readily detected by a scan limited to the region of abdominal tenderness.

Although in 16% of cases, the pathology wasn't even partially in the skin marker zone, in most of those instances it was doubtful that the pathology actually caused the abdominal pain. The rate of clinically relevant false-negative abdominal CT scans limited to the area of pain and tenderness was only 4%.

Dr. Broder and his associates also tested intermediately restricted CT, in which the entire abdomen and pelvis below the most cephalad skin marker of tenderness was scanned. This reduced radiation exposure by 38% and increased test sensitivity to 98%.

Based on the encouraging results in a nonconsecutive series, Dr. Broder plans to perform a larger, double-blind study in a consecutive series of similar patients.

NEW ORLEANS — Abdominal computed tomography limited to the region of tenderness accurately delineates acute pathology while reducing radiation exposure, according to a double-blind study.

A standard abdominal CT scan covers an area from above the diaphragm to the mid-thigh. But in the study, limiting the scan to the tender area cut radiation exposure by a mean of 69% while preserving 96% sensitivity, Dr. Joshua Broder said at the annual meeting of the Society for Academic Emergency Medicine.

The 93 patients in the single-center study underwent standard abdominal CT after presenting to the emergency department with nontraumatic abdominal tenderness. Before imaging, emergency physicians placed skin markers to delineate the cephalocaudad extent of tenderness. Then they added coded meaningless markers so radiologists would remain blinded to the region of tenderness, said Dr. Broder of Duke University Medical Center, Durham, N.C.

Of the 93 patients, 51 ultimately were found to have abdominal pathology, most commonly acute appendicitis. In one-third of cases, the pathology identified by radiologists was completely contained in the area highlighted by the skin markers of abdominal tenderness; in another 51%, the pathology was partially located in the marked zone and would have been readily detected by a scan limited to the region of abdominal tenderness.

Although in 16% of cases, the pathology wasn't even partially in the skin marker zone, in most of those instances it was doubtful that the pathology actually caused the abdominal pain. The rate of clinically relevant false-negative abdominal CT scans limited to the area of pain and tenderness was only 4%.

Dr. Broder and his associates also tested intermediately restricted CT, in which the entire abdomen and pelvis below the most cephalad skin marker of tenderness was scanned. This reduced radiation exposure by 38% and increased test sensitivity to 98%.

Based on the encouraging results in a nonconsecutive series, Dr. Broder plans to perform a larger, double-blind study in a consecutive series of similar patients.