Increased ⁶⁷gallium uptake among polymyalgia rheumatica patients. Is it additional evidence of its vasculitic nature?

Giant cell arteritis/temporal arteritis (GCA/TA) and polymyalgia rheumatica (PMR) are closely related conditions that affect middle age and older patients and frequently occur together. Many authorities consider them to be different phases of the same disease. A study was undertaken of the possible contribution of gallium-67 (⁶⁷Ga) single photon emission tomography (SPECT) scintigraphy to the diagnosis of GCA/TA and PMR, and to support the possible hypothesis of vasculitic nature of PMR. Nine consecutive patients with PMR, and nine consecutive patients with GCA/TA were included in the study. All patients fulfilled the American College of Rheumatology criteria for GCA/TA and Healey's criteria for PMR. The control patients group consisted of those who underwent ⁶⁷Ga scintigraphy for febrile illness. All patients and controls underwent ⁶⁷Ga SPECT scan of the skull on a dual-head Helix gamma camera 2 days after I.V. injection of 8-10 mCi of ⁶⁷Ga citrate. ⁶⁷Ga uptake ratio of temporal bone region to bone out of temporal area (TR/Bone) was estimated on transaxial and coronary slices after SPECT scan reconstruction. For each patient and control the calculations of both temporal areas were done. All GCA/TA and PMR patients showed increased uptake in both temporal areas of the skull, while ⁶⁷Ga uptake among GCA/TA was the highest, 1.31±0.14 in tranaxial view and 1.47±0.16 in coronary view. ⁶⁷Ga uptake among PMR patients was lower, 1.19±0.11 and 1.28±0.13, respectively. In comparison, the control patients showed the lowest ⁶⁷Ga uptake, 1.04±0.09 in transaxial view and 1.11±0.06 in coronary view. The results differ significantly between the three groups. It seems that ⁶⁷Ga SPECT scan may become a useful tool in the investigation of patients with suspicion of GCA/TA and PMR. Our findings of the increased ⁶⁷Ga uptake in the temporal areas among PMR patients add new arguments for vasculitic nature of this disorder.