Computed tomography and ultrasonography in the diagnosis of appendicitis: when are they indicated?

HYPOTHESIS: Relative merits and indications exist for ultrasonography (US) and computed tomography (CT) in the diagnosis of appendicitis. DESIGN: Prospective study. SETTING: General community and tertiary care hospital. METHODS: Ninety-nine patients (50 males and 49 females) were studied. Following consent, the initial disposition was recorded, designating the patient for operation, observation, or discharge from the hospital. Each patient was studied by CT and US. Studies were independently evaluated by 2 radiologists, and the results were designated as positive, negative, or equivocal. The surgeon reevaluated patients before and after learning the results of US and CT, recording whether the CT scan, US, or reexamination influenced the final disposition. RESULTS: Fifty patients had appendicitis; 6 appendixes were perforated. The initial clinical impression called for 44 operations, 49 observations, and 6 discharges. Thirty-four patients had their treatment plan changed from the initial disposition. Ultrasonography did not affect the initial impression. In contrast, 18 patients were rediagnosed solely on CT scan findings. Seven patients were rediagnosed by reexamination. Of 44 patients initially designated for operation, the CT scan and reexamination spared 6 females from surgery; the negative appendectomy rate potentially decreased from 50% to 17% (P =.03). The CT scan, US, or reexamination failed to spare 2 males from exploration with negative results. Of the 49 patients initially designated for observation, 23 were rediagnosed after reevaluation, 13 were discharged from the hospital, and 10 underwent expedient operation. One patient was spared from inappropriate discharge from the hospital. The reliability of the CT scan was good, with high sensitivities and specificities. Equivocal scan results lowered the diagnostic value. CONCLUSIONS: Selective use of a CT scan with a second examination can improve the diagnostic accuracy and management of suspected cases of appendicitis by (a) reducing the negative appendectomy rate in females, (b) moving patients from observation to earlier operation or discharge from the hospital, and (c) preventing inappropriate discharge of patients with appendicitis.

Expanded applications of CT. Helical scanning in five common acute conditions.

Helical CT has become a valuable imaging tool for detection of pulmonary embolism, deep venous thrombosis, ureteral colic, acute small-bowel obstruction, and acute appendicitis. Generally, helical CT has good sensitivity and specificity values, and scans can be performed more quickly than previous gold standard diagnostic examinations for the conditions mentioned. In some cases, helical CT can also identify other findings that may be responsible for a patient's symptoms. One notable disadvantage of helical CT is the charge for the procedure, which in some circumstances can be considerably more costly than diagnostic examinations preferred previously. However, because helical CT can often obviate the need for other tests--and may consequently reduce hospital stays--this technology may have the ability to reduce overall expenditures. Cost of helical CT is therefore a multifaceted issue and requires further study before conclusions can be drawn.

Computer-aided mammographic screening for spiculated lesions.

PURPOSE: To study the use of a computer vision method as a second reader for the detection of spiculated lesions on screening mammograms. MATERIALS AND METHODS: An algorithmic computer process for the detection of spiculated lesions on digitized screen-film mammograms was applied to 85 four-view clinical cases: 36 cases with cancer proved by means of biopsy and 49 cases with negative findings at examination and follow-up. The computer detections were printed as film with added outlines that indicated the suspected cancers. Four radiologists screened the 85 cases twice, once without and once with the computer reports as ancillary films. RESULTS: The algorithm alone achieved 100% sensitivity, with a specificity of 82%. The computer reports increased the average radiologist sensitivity by 9.7% (P = .005), moving from 80.6% to 90.3%, with no decrease in average specificity. CONCLUSION: The study demonstrated that computer analysis of mammograms can provide a substantial and statistically significant increase in radiologist screening efficacy.

Stroke associated with coronary artery bypass surgery.

Medical records and neuroimaging studies of 30 patients with major neurologic events after coronary artery surgery were reviewed. Two thousand and twenty-nine coronary artery bypass graft operations were performed in our institution between October 15, 1985, and December 27, 1989. Of these, there were 30 documented neurologic events suggesting acute ischemic injury during the intraoperative or the postoperative period. Clinical manifestations included hemiparesis, monoparesis, aphasia, bilateral cortical dysfunction, cortical and brainstem dysfunction, and left homonymous hemianopsia. There were five deaths directly attributable to neurologic injury. Twenty-two patients had a CT scan of the head, of which 15 showed evidence of acute infarction, two suggested watershed lesions from cerebral hypoperfusion, and the remainder showed findings consistent with multiple cerebral emboli or primary intracranial occlusion. Five carotid arteriograms and one digital subtraction arteriogram of the carotids were obtained. Angiographic findings revealed two common carotid artery occlusions, one callosal marginal artery occlusion, and two cases of bilateral high-grade internal carotid stenoses. Our findings support the contention that in patients who suffer cerebral infarction associated with coronary artery bypass grafting, the main mechanism of injury is cerebral embolization rather than cerebral hypoperfusion.