Clinical impact of 99mTc-HDP SPECT/CT imaging as standard workup for foot and ankle osteoarthritis.

Objective: The primary aim of this study was to assess to what extent 99mTc-HDP Single photon emission computed tomography/computed tomography (SPECT/CT) will lead to change of diagnosis and treatment, in patients with suspected foot and ankle osteoarthritis (OA). Secondary aim was to assess the intraobserver variability. Methods: Retrospectively 107 patients, with suspected foot and/or ankle OA of which a SPECT/CT was made, were included for analysis. All the clinical and radiological data were randomized and blinded before being scored by one experienced orthopaedic surgeon. Firstly, based on the clinical data and conventional radiographs, a diagnosis and treatment plan was scored. Secondly, the observer accessed the SPECT/CT and could change the diagnosis and treatment plan. Additionally, the intraobserver reliability was determined by data of 18 patients that were added in twofold to the dataset, without awareness of the observer and by calculating the κ values. Results: The diagnosis changed in 53% (57/107) and treatment plans changed in 26% (28/107) of the patients. Intraobserver reliability for the conventional workup was k = 0.54 (moderate strength of agreement), compared to k = 0.66 (substantial strength of agreement) when SPECT/CT data were added. Conclusions: This study describes the influence of SPECT/CT on diagnosis and treatment plans in patients with suspected symptomatic OA. Also, it shows SPECT/CT leads to a higher intraobserver variability. We believe SPECT/CT has a promising role in the workup for foot and ankle OA. Advances in knowledge: In addition to what was found in complex foot and ankle cases, this study shows that in patients with non-complex foot and ankle problems, SPECT/CT has a substantial influence on the diagnosis (and subsequent treatment plan).

Comparison of MRI, CT and bone scintigraphy for suspected scaphoid fractures.

PURPOSE: The best diagnostic modality for confirmation of the diagnosis of a scaphoid fracture that is not visible on the initial radiograph (occult scaphoid fracture) is still subject of debate. The aim of this study was to compare the accuracy of magnetic resonance imaging (MRI), computed tomography (CT) and bone scintigraphy (BS) for the diagnosis of these occult scaphoid fractures. PATIENTS AND METHODS: In a study period of 12 months, 33 consecutive patients with a clinically suspected scaphoid fracture without a fracture on the scaphoid radiographs were evaluated with MRI, CT and BS. In case of a discrepancy between the diagnostic modalities, the final diagnosis was based on standardised follow-up with clinical examination and a repeated radiograph. RESULTS: Three of the 33 patients had a scaphoid fracture. MRI missed one scaphoid fracture and did not over-diagnose. CT missed two scaphoid fractures and did not over-diagnose. BS missed no scaphoid fractures and over-diagnosed one scaphoid fracture in a patient with a fracture of the trapezium. CONCLUSION: 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.

MRI as a reference standard 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 κ=0.44; p<0.001). CONCLUSIONS: The specificity of MRI for scaphoid fractures is high (96%), but false-positives 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.