QUANTITATIVE RADIOSCINTIGRAPHY: A SENSITIVE, SPECIFIC, AND ACCESSIBLE METHOD FOR THE DIAGNOSIS OF OCCULT FRACTURES OF THE CARPAL BONE

Abstract

Purpose of the study: Occult fractures of the carpal bone are underestimated. An undetected fracture of the scaphoid will not be immobilized and will lead to nonunion and osteoarthritic degradation. In order to avoid late diagnosis and functional loss, in addition to lost chances and legal suites, we validated a quantitative radioscin-tigraphic (QRS) tool in a randomized prospective trial conducted from 1997 to 2003 in a routine practice setting. The series included 667 patients with wrist trauma presenting a normal plain x-ray one day 0. After day 8 these patients underwent QRS.

Material and methods: The principle of the technique consists in a classical technetium scintigraphy with two technical improvements:

1. quantification of uptake: uptake two-fold greater on the injured side is a sign of «certain» fracture;

2. software superposition of the scintigraphic image and the radiographic image used to localize the bone fracture.

Results: Forty percent of the wrist trauma patients (260/667) with a normal plain x-ray presented an occult fracture (uptake > 2 on QRS). QRS was performed on day 17.7 on average. Fractures of the scaphoid were the most frequent (42%). The uptake ratio was higher if the QRS was performed from day 11 to day 20. Statistical analysis showed that uptake ratio > 2 was independent of age, gender, bone volume, and time to QRS.

Discussion: As demonstrated by Dikson, Dias, Thomp-son and Kuckla, repeated x-ray images do not increase the rate of diagnosis of carpal bone fractures. Spitz demonstrated that scintigraphic uptake on the trauma side more than twice that on the healthy side is a sign of fracture. Garbuio, NOvert and Lepage validated QRS as a sensitive and specific diagnostic tool for occult fractures. They demonstrated that QRS is less costly, more reliable than MRI and that there are no false positives.

Conclusion: Exploration of a «bone problem» in a patient with wrist trauma must not ignore sensitive and specific tests. Ultrasonography is operator-dependent and requires validation. We thought that QRS would not resist the development of routine MRI, but observed the contrary. QRS remains the gold standard diagnostic tool for ruling out a fracture of the carpal bones.