Many rheumatologists and radiologists routinely assess conventional radiographs of the hands, and it is often unclear how to proceed if radiography reveals only cyst-like lesions (CLLs), with otherwise normal findings. The present study was undertaken to evaluate the use of 320-row multidetector computed tomography (MDCT) of the hands in the further assessment of CLLs of metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints identified on conventional radiography.
MCP and PIP joints (n = 1,120 joints) of 56 consecutive patients (44 women [mean age 55 years, range 31-72 years] and 12 men [mean age 57 years, range 37-77 years]) were prospectively scored for the presence of cysts, CLLs, and erosions of the PIP and MCP joints, first on conventional radiographs, then on MDCT. Scoring was performed by 2 independent readers under blinded conditions. Intraclass correlation coefficients were calculated.
By conventional hand radiography, 13 patients (total of 260 joints assessed) were identified as having CLLs in 1 or more joints (total of 36 joints [11 PIP and 25 MCP]). By MDCT, the findings in 19 of 36 joints (53%) were diagnosed as erosions, while 7 of 36 (19%) were confirmed as true cysts, and 10 joints (28%) were normal (false positive). Among the patients with CLLs, 10 of 224 joints with no abnormality seen radiographically had erosions as seen on MDCT. Interreader agreement for erosions was 0.854 (95% confidence interval [95% CI] 0.831-0.874) by conventional hand radiography and 0.952 (95% CI 0.943-0.959) by MDCT.
Our results indicate that radiographic appearance of cyst-like lesions may actually represent erosions and should lead to initiation of further imaging tests.