Pathological implications of areas of lower enhancement on contrast-enhanced computed tomography in renal-cell carcinoma: additional information for selecting candidates for surveillance protocols.
OBJECTIVE
Areas of lower enhancement on computed tomography are frequently seen in renal-cell carcinoma. We investigated whether tumor enhancement on the most prominent hypodense areas correlates with the nuclear grade and other pathologic variables.


METHODS
From 2004 to 2009, all consecutive patients with a preoperative tomography who underwent radical or partial nephrectomy for renal-cell carcinoma at our tertiary referral center were retrospectively analyzed. Enhancement of the entire tumor on the slice with most prominent areas of lower enhancement was determined.


RESULTS
Forty-eight patients were included. Clear-cell carcinoma comprised 91.6 %. Mean areas of lower enhancement for nuclear grade tumors 1-4 were 67.4, 38.7, 27.9, and 15.1 HU, respectively. Areas of lower enhancement negatively correlated with size, nuclear grade, T stage, and pathological stage. Tumors with extension beyond Gerota's fascia (10.5 vs. 35.9 HU, p < 0.001) and positive surgical margins (21.2 vs. 34.8 HU, p = 0.04) had more prominent areas of lower enhancement than organ-confined tumors. When comparing nuclear grade 1-3 to nuclear grade 4 tumors, these areas were significantly lower in the later (36.5 vs. 15.1 HU, p < 0.001). Receiver-operating characteristics curves for detecting nuclear grade 4 showed an area under the curve of 0.808 (95 % CI 0.659-0.957).


CONCLUSIONS
Lower enhancement of the entire tumor at the point where hypodense tumor areas are more predominant on tomography is associated with higher nuclear grade and more advanced stage.
Department of Urology, Hospital Regional de Alta Especialidad de la Peninsula de Yucatan, Merida, Mexico.
Miguel
M
Villalobos-Gollás
Bernardo
B
Aguilar-Davidov
Carolina
C
Culebro-García
Martha O
MO
Gómez-Alvarado
Priscila
P
Rojas-Garcia
Raúl
R
Ibarra-Fombona
Norma
N
Uribe-Uribe
Guillermo
G
Feria-Bernal
Ricardo
R
Castillejos-Molina
Mariano
M
Sotomayor
Fernando
F
Gabilondo
Francisco
F
Rodríguez-Covarrubias
D019540:Area Under Curve; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D003287:Contrast Media; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D008297:Male; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009392:Nephrectomy; D011159:Population Surveillance; D012372:ROC Curve; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed
D003287:Contrast Media