Tc-99m PMT hepatobiliary scintigraphy in the differential diagnosis of extrahepatic metastases and hepatocellular carcinoma.
OBJECTIVE
The authors evaluated the utility of hepatobiliary scintigraphy for tissue characterization of extrahepatic metastases from hepatocellular carcinoma (HCC) using Tc-99m N-pyrydoxyl-5-methyltriptophane (Tc-99m PMT).


METHODS
We examined 13 patients with HCC (29 extrahepatic metastases and 3 benign bone lesions) and 5 patients with other cancers (15 extrahepatic metastases). Thirty minutes to 6 hours after intravenous administration of Tc-99m PMT, planar (all 47 lesions) and SPECT (42 lesions) images were obtained. Accumulation of Tc-99m PMT in the lesion was evaluated visually by comparing bone scintigraphy, computed tomography, magnetic resonance imaging, or all of these.


RESULTS
Findings were positive in 12 of 13 patients with HCC and extrahepatic metastases (16 of 29 on planar imaging and 21 of 26 on SPECT). Findings in all three benign bone lesions and 15 metastatic lesions from non-HCC primary lesions were negative (0 of 18 on planar imaging, 0 of 16 on SPECT). There were no false-positive findings in these lesions. Lesion-by-lesion sensitivity, specificity, accuracy, and positive and negative predictive values were 55%, 100%, 72%, 100%, and 58% by planar imaging and 81%, 100%, 88%, 100%, and 76% by SPECT, respectively.


CONCLUSIONS
Because of the high specificity and reasonable sensitivity, Tc-99m PMT appears to be useful for the differential diagnosis of extrahepatic metastases from HCC. SPECT improves the detectability of small or faint accumulation in metastases from HCC.
Mochizuki
T
T
Department of Radiology, Ehime University School of Medicine, Onsen-gun, Japan. tmochi@m.ehime-u.ac.jp
Tsuda
T
T
Sugawara
Y
Y
Tanaka
H
H
Kikuchi
T
T
Miyagawa
M
M
Shimizu
K
K
Murase
K
K
Iuchi
H
H
Onji
M
M
Ikezoe
J
J
D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000556:secondary*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D008297:Male; D015609:Organotechnetium Compounds; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D013669:Technetium Tc 99m Medronate / Q000031:analogs & derivatives*; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014364:Tryptophan / Q000031:analogs & derivatives*
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C034836:technetium Tc 99m (Sn)-N-pyridoxyl-5-methyltryptophan; C024226:technetium Tc 99m hydroxymethylene diphosphonate; D014364:Tryptophan; D013669:Technetium Tc 99m Medronate