This study could not confirm that early CT imaging is superior to bone scintigraphy for suspected scaphoid fractures.
Objectives: Some have suggested that MRI might be the best reference standard for a true fracture among patients with suspected scaphoid fractures. The primary aim of this study was to determine the rate of false-positive diagnosis of an acute scaphoid fracture in a cohort of healthy volunteers. Methods: In a prospective study, 33 healthy volunteers were recruited and both wrists of each were scanned, except for 2 volunteers for whom only one wrist was scanned. To simulate the usual clinical context the 64 scans of healthy volunteers were mixed with 60 MRI scans of clinically suspected scaphoid fractures but normal scaphoid radiographs. These 124 MRI scans were blinded and randomly ordered. Five radiologists evaluated the MRI scans independently for the presence or absence of a scaphoid fracture and other injuries according to a standard protocol. Results: To answer the primary question, only the diagnoses from the 64 scans of healthy volunteers were used. The radiologists diagnosed a total of 13 scaphoid fractures; therefore, specificity for diagnosis of scaphoid fracture was 96% (95% confidence interval: range 94-98%). The 5 observers had a moderate interobserver agreement regarding diagnosis of scaphoid fracture in healthy volunteers (multirater k50.44; p,0.001). Conclusions: The specificity of MRI for scaphoid fractures is high (96%), but falsepositives do occur. Radiologists have only moderate agreement when interpreting MRI scans from healthy volunteers. MRI is not an adequate reference standard for true fractures among patients with suspected scaphoid fractures. The American College of Radiologists recommends MRI for diagnosis of true fractures among suspected scaphoid fractures [1]. A number of published studies cite sensitivities and specificities approaching 99% [2-9], but other studies have reported a lower sensitivity (80%) and substantial interobserver variation (k50.67) for diagnosis of a scaphoid fracture [2,8]. It has been difficult to agree upon a reliable reference standard for true fractures among suspected scaphoid fractures, and these studies often use only repeated radiographs 6 weeks after trauma as reference standard. However, it is also known that not all occult scaphoid fractures become apparent on repeated radiographs.It is not clear how to distinguish true fracture from other changes in bone signal that are detected with MRI. We propose that MRI of the wrists of healthy volunteers with no history of wrist or hand injury represents a reliable reference standard for the absence of an acute fracture of the scaphoid waist. By evaluating MRI scans of healthy volunteers, we may learn more about the diagnostic performance characteristics of MRI for suspected scaphoid fracture. A set of MRI scans with a reliable reference standard would also provide useful information about the reproducibility of the interpretation of MRI for suspected scaphoid fracture.The primary study question was to investigate the occurrence of false-positive diagnosis of an acute scaphoid fracture on MRI using a reliabl...
This study shows that neither MRI, nor CT and BS are 100 % accurate in diagnosing occult scaphoid fractures. MRI and CT miss fractures, and BS tends to over-diagnose. The specific advantages and limitations of each diagnostic modality should be familiar to the treating physicians and taken into consideration during the diagnostic process.
i cine published our study, examining whether multidetector CT is superior to bone scintigraphy for diagnosing radiographically occult scaphoid fractures. 1 Based on the results in this consecutive series of 100 patients, we could not confirm that early CT is superior to bone scintigraphy for suspected scaphoid fractures.We initially stopped after inclusion of 100 patients. However, throughout the following period, we were fortunate enough to continue inclusions to 159 patients. With this extended group of patients, we were able to provide more significant results. We would like to present the final results of our study to the readers of Clinical Nuclear Medicine. The design of the study is described in our previous publication. 1 In a period of 39 months, a total number of 159 consecutive patients with a suspected scaphoid fracture visited the emergency department, 79 of whom were male and 80 were female, with a mean age of 41 years (range, 17Y88 y).CT scans showed 15 scaphoid and 35 other fractures. Bone scintigraphy showed 28 scaphoid and 57 other fractures. According to the reference standard, there were 20 scaphoid fractures. One CT scan was false-positive and CT missed 6 scaphoid fractures. Bone scintigraphy was false-positive in 9 cases and missed 1 scaphoid fracture.CT had a sensitivity of 70%, specificity of 99%, accuracy of 96%, a positive predictive value of 93%, and a negative predictive value of 96%. Bone scintigraphy had a sensitivity of 95%, specificity of 94%, accuracy of 94%, a positive predictive value of 68%, and a negative predictive value of 99%.The percentages of sensitivity, specificity, and correct predictions (accuracy) were compared for the 2 diagnostic methods with a McNemar test. Although the sensitivity of CT seemed to be lower (70%) than that of bone scintigraphy (95%), this could not be confirmed statistically (P = 0.13), probably because of the small number of scaphoid fractures (n = 20). Accuracy did not differ significantly either between CT and bone scintigraphy (P = 0.63). The specificity of CT was significantly better than that of bone scintigraphy (P = 0.02). On the basis of these results, CT seems the investigation of choice for ruling in, and bone scintigraphy for ruling out, a scaphoid fracture in clinically suspected patients.In conclusion, after increasing the power of our study with additional data, our previous statement is confirmed that early CT imaging is not superior to bone scintigraphy for suspected scaphoid fractures. REFERENCE 1. Rhemrev SJ, de Zwart AD, Kingma LM, et al. Early computed tomography compared with bone scintigraphy in suspected scaphoid fractures. Clin Nucl Med. 2010;35:931Y934.
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