The decision for treatment with 224RaCl always should be made in close collaboration of the nuclear medicine specialist and the rheumatologist. Diagnosis of AS and a failure of conservative pharmacotherapy with both nonsteroidal anti-inflammatories and analgesics, or the presence of specific contraindications against these drugs are a prerequisite. The patients frequently complain of lower back pain, severe morning stiffness in the back and spine, and of breathing impairment owing to progressive inflammation and stiffening of their chests.
Table 3 Indications for 224RaCl (Radium Chloride) Treatment
Diagnosis of ankylosing spondylitis by a rheumatologist Failure of conservative pharmacotherapy
Active mineralization processes in the axial skeleton (referring to stages 2 and 3)
Only patients with active mineralization processes in the axis skeleton should be selected for 224RaCl therapy. Following the clinical and radiological classifications, those are particularly patients showing areas of progressive ossification in the sacroiliac joints and in at least two spine regions referring to the historical illness stages II and III of AS (17,18).
In later stages, presenting with an almost complete spinal ankylosis (so-called "bamboo stick spine' ), 224RaCl therapy is no longer reasonable. Furthermore, in these patients, the pain is frequently regressive. Active mineralization zones, into which the calcium analog, 224RaCl, is firmly incorporated, can be easily proven by bone scintigraphy, showing local accumulation of the bone-seeking 99mTc-HDP (99 m technetium-hydroxy-methylene-phosphonate) on the delayed images 3-h postinjection. Evidence of an increased mineralization, for example, in the chest or the spine, is an indication for radionuclide therapy with 224RaCl (Table 3). Figure 1 shows an example of active multifocal mineralization processes on the delayed images of a whole-body bone scan in a patient with AS (Fig. 1).
Contraindications are pregnancy and breastfeeding; adolescents with still-active metaphyseal growth plates; history of hematopoietic diseases or cancer; recent bone fractures; impaired liver function; acute infections; and preceeding treatment with drugs toxic to the bone marrow (Table 4).
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