Use of computed tomography assessed kidney length to predict split renal GFR in living kidney donors.

OBJECTIVES: Screening of living kidney donors may require scintigraphy to split glomerular filtration rate (GFR). To determine the usefulness of computed tomography (CT) to split GFR, we compared scintigraphy-split GFR to CT-split GFR. We evaluated CT-split GFR as a screening test to detect scintigraphy-split GFR lower than 40 mL/min/1.73 m2/kidney. METHODS: This was a monocentric retrospective study on 346 potential living donors who had GFR measurement, renal scintigraphy, and CT. We predicted GFR for each kidney by splitting GFR using the following formula: Volume-split GFR for a given kidney = measured GFR*[volume of this kidney/(volume of this kidney + volume of the opposite kidney)]. The same formula was used for length-split GFR. We compared length- and volume-split GFR to scintigraphy-split GFR at donation and with a 4-year follow-up. RESULTS: A better correlation was observed between length-split GFR and scintigraphy-split GFR (r = 0.92) than between volume-split GFR and scintigraphy-split GFR (r = 0.89). A length-split GFR threshold of 45 mL/min/1.73 m2/kidney had a sensitivity of 100 % and a specificity of 75 % to detect scintigraphy-split GFR less than 40 mL/min/1.73 m2/kidney. Both techniques with their respective thresholds detected living donors with similar eGFR evolution during follow-up. CONCLUSION: Length-split GFR can be used to detect patients requiring scintigraphy. KEY POINTS: • Excellent correlation between kidney length and scintigraphy predicted GFR • Kidney length screening detects all donors with GFR lower than 40 mL/min/1.73 m 2 • Kidney length screening can replace scintigraphy screening.

Three-phase Bone Scintigraphy Can Predict the Analgesic Efficacy of Ketamine Therapy in CRPS.

OBJECTIVES: The efficacy of ketamine in relieving complex regional pain syndrome (CRPS) lacks predictive factors. The value of three-phase bone scintigraphy (TPBS) was assessed for this purpose. MATERIALS AND METHODS: TPBS was performed in 105 patients with unilateral, focal CRPS of type 1 before 5 days of ketamine infusions. Tracer uptake was measured in the region of interest concerned by CRPS and the contralateral homologous region. For the 3 scintigraphic phases (vascular, tissular, and bone phases), an asymmetry ratio of fixation was calculated between the affected and the unaffected sides (vascular phase [VPr], tissular phase [TPr], and bone phase [BPr]). Ketamine efficacy was assessed on pain intensity scores. RESULTS: Ketamine-induced pain relief did not correlate with VPr, TPr, and BPr, but with the ratios of these ratios: BPr/TPr (r=0.32, P=0.009), BPr/VPr (r=0.34, P=0.005), and TPr/VPr (r=0.23, P=0.02). The optimum cut-off value for predicting the response to ketamine therapy was >1.125 for BPr/TPr, >1.075 for BPr/VPr, and >0.935 for TPr/VPr. The combination of increased values of BPr/TPr, BPr/VPr, and TPr/VPr was highly significantly associated with ketamine therapy outcome. CONCLUSIONS: The relative hyperfixation of the radioactive tracer in the limb region concerned by CRPS in phases 2 and 3 versus phase 1 of TPBS correlated positively to the analgesic efficacy of ketamine. This study shows for the first time the potential predictive value of TPBS regarding ketamine therapy outcome. In addition, these results suggest that the analgesic action of ketamine is not restricted to "central" mechanisms, but may also involve "peripheral" mechanisms related to tissue inflammation and bone remodeling.