USE OF SPIRAL AND NON-SPIRAL COMPUTED-TOMOGRAPHY ARTERIAL PORTOGRAPHYIN THE DETECTION OF POTENTIALLY MALIGNANT LIVER MASSES

The present study assesses the usefulness of computed tomography (CT) arterial portography (CTAP) in detecting and defining the number and a natomy of potentially malignant liver lesions. One hundred and one adu lts studied in 1993 and 1994 were retrospectively reviewed, including patients with primary or secondary rumours for possible resection and patients with non-hepatic malignancies in whom the detection of liver metastases would preclude surgery. Twenty-three patients underwent non -spiral CT studies and 78 had studies on a spiral unit, with 22 of the se having single phase and 56 having dual phase studies to overcome ar tefact problems. The relationship between lesion size and detection se nsitivity is critical. On non-spiral studies, the overall lesion detec tion sensitivity and positive predictive value was 69 and 90%, respect ively. Detection sensitivity was 100 and 20% for lesions >1 cm and <1 cm, respectively On single phase spiral CTAP the overall detection sen sitivity and positive predictive value was 80and 66%, respectively. De tection sensitivity for lesions >1 cm and <1 cm was 100 and 0%, respec tively. On dual phase spiral CTAP the overall detection sensitivity an d positive predictive value was 76 and 71%, respectively. For lesions >1 cm and <1 cm the sensitivity was 81 and 55%, respectively. Eighteen patients with non-hepatic malignancies with unsuspected metastatic sp read did not proceed to major surgery because of liver metastases dete cted on CTAP. Perfusion artefacts occurred in 30 and 64% of non-spiral and of initial portal venous spiral CTAP studies, respectively. By us ing the double-phase technique, these artefacts were substantially dim inished. In conclusion, CTAP is a valuable tool for assessing the pres ence, site and size of possible liver rumours and confers a benefit ev en when previous ultrasound and conventional CT have already been used . In addition, CTAP has a lower limit of useful resolution of approxim ately I cm. Perfusion artefacts can be reduced by a dual phase protoco l.