ABSTRACT
The ability to measure cellular proliferation non-invasively in renal cell carcinoma may allow prediction of tumour aggressiveness and response to therapy. The aim of this study was to evaluate the uptake of 18F fluorothymidine [FLT] PET in renal cell carcinoma [RCC], and to compare this to 18F-fluorodeoxyglucose [FDG], and to an immunohistochemical measure of cellular proliferation [Ki-67]. Twenty seven patients [16 male, 11 females; age 42-77] with newly diagnosed renal cell carcinoma suitable for resection were prospectively enrolled. All patients had preoperative FLT and FDG PET scans. Visual identification of tumour using FLT PET compared to normal kidney was facilitated by the use of a pre-operative contrast enhanced CT scan. After surgery tumour was taken for histologic analysis and immunohistochemical staining by Ki-67. The SUVmax [maximum standardized uptake value] mean +/- SD for FLT in tumour was 2.59 +/- 1.27, compared to normal kidney [2.47 +/- 0.34]. The mean SUVmax for FDG in tumour was similar to FLT [2.60 +/- 1.08]. There was a significant correlation between FLT uptake and the immunohistochemical marker Ki-67 [r=0.72, P<0.0001] in RCC. Ki-67 proliferative index was mean +/- SD of 13.3% +/- 9.2 [range 2.2% - 36.3%]. There is detectable uptake of FLT in primary renal cell carcinoma, which correlates with cellular proliferation as assessed by Ki-67 labelling index. This finding has relevance to the use of FLT PET in molecular imaging studies of renal cell carcinoma biology
ABSTRACT
Insulin is readily concentrated from 10 to 50 ml of urine with better than 75% recovery using octadecylsilyl (ODS) silica columns (C18Sep-Pak cartridge) and can then be measured by radioimmunoassay. Fractionation on Sephadex G50 gel filtration reveals that the apparent immunoreactivity corresponds for the most part to 6000 dalton insulin. Renal clearance of insulin in 5 normal subjects does not appear to differ in the fasted or fed state and ranged from 0.34 to 0.58 ml/min with an average of 0.44 +/- 0.10 (S.D.) ml/min. Increased urinary insulin output was observed following feeding and fell during prolonged fasting. Insulin output in urine from 7 non-diabetic subjects ranged from 11 to 39 mU/24 hr, averaging 25 +/- 10 mU/24 hr. In normal subjects without renal disease a single determination of renal insulin clearance and a timed urinary insulin output appear to be sufficient for determination of mean plasma insulin during that time period. Concentration of urine using this methodology could provide the material for HPLC screening for abnormal insulins and for their subsequent purification to determine the site of change in amino acid sequence.