Mishal Mendiratta-Lala MD, Presenter: Nothing to Disclose

Sofia Gourtsoyianni MD, Abstract Co-Author: Nothing to Disclose

Olga Rachel Brook MD, Abstract Co-Author: Nothing to Disclose

Bettina Siewert MD, Abstract Co-Author: Nothing to Disclose

Vassilios D. Raptopoulos MD, Abstract Co-Author: Nothing to Disclose

To determine the value of 3-min-delay phase in routine oncology follow up MDCT protocol for hepatic lesion detection and characterization

This is a retrospective IRB approved HIPPA compliant study of 39 patients who had known primary malignancy with potential for hypovascular liver metastasis and focal liver abnormalities seen on oncology MDCT protocol. Liver imaging was done without IV contrast followed by scans in portal venous (PV) phase and 3-min-delay phase. PV timing was determined by liver triggering during injection of bolus and start scanning at 50 HU enhancement threshold (48-75 sec). Two experienced abdominal radiologists assessed the data in consensus. Number of lesions visible on PV and/or delayed phases were counted. Up to 6 lesions per patient were evaluated for lesion characterization. A 5 point grading scale was used to assess readers’ confidence level of benignity or malignancy. Dose length product (DLP) for each phase was available.

Over a three month period 39 patients were identified. A total of 235 focal hepatic lesions were detected of which 143 (up to 6 per patient) were characterized. In the PV phase we counted 233 and in the delayed phase scans we counted 143 focal lesions (p<0.001). In 11 of 39 patients (28%) more lesions were detected on PV phase, ranging from 1 to 37 (mean 8.18, SD 12.6, median 2) additional lesions per patient. In only 1 of 39 patients (2%) additional lesions (n=2) were detected in the delayed phase (p = 0.005). In terms of characterization, 10 out of 143 (7%) evaluated lesions were given a higher confidence score with the addition of delayed images. Seven of these lesions were considered benign in nature (hemangiomas, cysts). Mean DLP of delayed phase ranged from 21% to 51% (124.4-888.6) of the total scan DLP, depending on whether the pelvis or chest was also scanned.

3-min delayed phase imaging in oncology MDCT does not increase exam’s sensitivity in detecting liver metastasis but increases confidence for lesion characterization. It can be safely eliminated in follow-up oncology scanning.

Portal venous phase MDCT is adequate for evaluation of liver metastasis and delayed phase imaging does not add in detection and marginally adds in lesion characterization.

Mendiratta-Lala, M, Gourtsoyianni, S, Brook, O, Siewert, B, Raptopoulos, V, The Value of 3-minute Delay Phase in Routine Oncology Follow-up MDCT for Hepatic Lesion Detection and Characterization.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034467.html