Focal nodular hyperplasia: CT findings with emphasis on multiphasic helical CT in 78 patients.
OBJECTIVE
To evaluate features of focal nodular hyperplasia (FNH) at multiphasic helical computed tomography (CT).


METHODS
Clinical, pathologic, and preoperative imaging findings were retrospectively reviewed in 78 patients. Conventional liver CT was performed in nine patients; helical multiphasic CT, in 69. Diagnosis was based on complete resection (n = 20), biopsy (n = 42), or clinical and imaging follow-up for a minimum of 6 months (n = 16). Number, size, location, margins, surface, homogeneity of enhancement, and presence of a central scar, mass effect, exophytic growth, calcification, pseudocapsule, or vessels feeding or draining the lesion were evaluated.


RESULTS
CT depicted 124 tumors (mean diameter, 4.1 cm; range, 1-11 cm); 62 were small (< or =3 cm). FNHs were hypervascular and hyperattenuating to liver on 106 of 106 arterial phase scans and were isoattenuating to liver on 82 of 89 delayed scans. Of the 124 tumors, 111 enhanced homogeneously, 109 had a smooth surface, 101 were subcapsular, 89 had ill-defined margins, and 62 had a central scar that was observed more often in large lesions (40 of 62 lesions) than in small lesions (22 of 62 lesions). FNHs less frequently exerted a mass effect (43 lesions), had vessels around or within the lesion (42 lesions), demonstrated exophytic growth (40 lesions), or showed a pseudocapsule (10 lesions). Only one FNH had calcification.


CONCLUSIONS
Helical CT demonstrates characteristic features that may allow confident diagnosis of FNH. In typical cases, neither biopsy nor further imaging is necessary.
Department of Radiology, University of Pittsburgh Medical Center, Presbyterian Hospital, 200 Lothrop St, Rm 4660 CHP MT, Pittsburgh, PA 15213-2582, USA.
G
G
Brancatelli
M P
MP
Federle
L
L
Grazioli
A
A
Blachar
M S
MS
Peterson
L
L
Thaete
D000293:Adolescent; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D020518:Focal Nodular Hyperplasia / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement; D014057:Tomography, X-Ray Computed