99mTc-albumin nanocolloid (NC) joint scintigraphy in rheumatoid arthritis patients who are in clinical remission

Objectives To find out whether the clinical criteria in rheumatoid arthritis truly categorize patients to be in remission or that some patients still have subclinical active joint disease.

Methods 40 RA patients in clinical remission were studied.A comparison between the clinical criteria and the imaging results with ^99mTc-NC scintigraphy was carried out.The clinical status of the patients was not known to the nuclear physician and scan visual interpretation was carried out while blinded to any laboratory or clinical data.Each patient was given an intravenous injection of 555 MBq of ^99mTc-NC 1-h prior to spot views of the wrists, hands, shoulders, pelvic joints and SPECT-CT of the wrists and hands.A scan was considered positive when the joint showed increased tracer uptake, irrespective of the number of positive joints, while diffuse tracer activity with no focal joint uptake was regarded as negative.

Results The patients consisted of 29 females and 11 males, mean age of 60.8 years (range 22-86 years) disease duration of 13.4 years (3-23 years) and mean remission 27 months (12-48 months).The ^99mTc-NC scintigraphy was negative in 16 and positive in 24.22 patients with positive scans were RF positive and 2 were sero-negative, while in those who had a negative scintigraphy only 2 patients were sero- positive while the others were sero-negative.

Conclusions The results of this study indicate that the clinical criteria used for remission in RA are not consistent with the actual inflammatory joint activity shown by ^99mTc-albumin nanocolloid.