Application of contrast-enhanced ultrasonography after radiofrequency ablation for renal cell carcinoma: is it sufficient for assessment of therapeutic response?
OBJECTIVE
To assess the efficacy of contrast-enhanced ultrasonography (CEUS) with Sonovue in the evaluation of therapeutic response to radiofrequency ablation (RFA) of renal cell carcinoma (RCC).


METHODS
In a recent 3 years, 63 patients (mean age, 60 years; range 26-81 years) with 64 RCCs were treated by RFA. The lesions had a diameter between 1.8 and 9.8 cm (average diameter, 3.1 cm). The indications for RFA treatment included chronic renal insufficiency (n = 10), presence of solitary kidney (n =3), bilateral renal carcinoma (BRCC) (n =2), advanced age (n =12), significant medical comorbidity (n =29) or refusal of conventional therapy (n =7). Tumors were treated by laparoscopy-assisted (n =41), open surgical (n =18) or percutaneous US guidance (n =4). Follow-up CEUS and contrast-enhanced CT were performed 1 month after treatment to assess the necrotic area. Technical success was defined as elimination of areas that enhanced at imaging within the entire tumor.


RESULTS
On the 1-month CEUS and CT imaging after RFA, 62 of 64 tumors (96.9%) were successfully ablated with one session, and residual tumors were found in two RCCs. One of the two tumors was subjected to additional RFA treatment. We could not obtain a complete ablation in the other tumor of a patient with solitary kidney. The diagnostic concordance between the CEUS and 1-month follow-up CT was 100%. Sixty-one patients survived in the follow-up phase which ranged from 2 to 34 months. One patient with solitary kidney died of systemic disease progression and one patient was lost to follow-up. Of the 61 tumors without residual on both CT and CEUS after RFA, four had suspicious findings of recurrence on follow-up CEUS, and two of them were confirmed by subsequent CT examination. With CT as the reference imaging procedure in the assessment of renal tumor ablation, the sensitivity, specificity, positive predictive value, and negative predictive value of CEUS for detecting recurrence during follow-up were 100%, 96.6%, 50%, and 100%.


CONCLUSIONS
Despite its limitation of false-positive value, CEUS is potentially effective in assessing the therapeutic response to RFA of RCC.
Ultrasonic Room of Surgery, Drum Tower Hospital, Medical College of Nanjing University, China.
Wen-Tao
WT
Kong
Wei-Wei
WW
Zhang
Hong-Qian
HQ
Guo
Jun-Lan
JL
Qiu
Min
M
Tang
Zhi-Min
ZM
Jiang
Yi
Y
Shen
Xiao-Gong
XG
Li
Shi-Wei
SW
Zhang
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000601:surgery*; D017115:Catheter Ablation; D003287:Contrast Media; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010743:Phospholipids; D013459:Sulfur Hexafluoride; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride