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Twelve athletes presenting acute knee injury with normal radiological findings underwent both three-phase radionuclide bone imaging (TPBI) and magnetic resonance imaging (MRI). The association of these highly sensitive diagnostic procedures detected occult fractures in all patients. The areas of signal intensity alterations on MRI corresponded to those of increased radionuclide uptake in blood pool images. However, the same areas seemed to be more extended on delayed TPB images. TPBI yielded early diagnostic information about lesion sites and functional activities, while MRI provided better anatomical definition and specific information about associated soft tissue lesions and served to establish the correct therapeutic approach and follow-up.

Comparison between the plasma levels of intravenously injected technetium 99m hydroxy methylene [corrected] diphosphonate (99mTc-HMDP) and chromium 51 ethylene diamine tetra-acetic acid (51Cr-EDTA) reflects the uptake of diphosphonate into bone (the diphosphonate space). This can be used as an index of skeletal function in metabolic bone disease. In a series of 49 patients with Paget's disease the diphosphonate space (DPS) correlated well with other indicators of disease activity such as alkaline phosphatase and urinary hydroxyproline levels. The DPS is a good predictor of the volume of skeletal involvement as estimated from bone images. The DPS also provides a sensitive indicator of response to treatment with intravenously administered bisphosphonate. The DPS is simple to perform and is a useful adjunct to routine bone imaging.

Bone imaging was done in patients after total replacement arthroplasty of the hip joint every 3rd month using 99mTc-HEDP and 18F. Uptake ratios were estimated over cup/normal hip and femur prosthesis/normal thigh. Ratios decline rapidly and reach a stable level 6–9 months, postoperatively. Eight cases of late infection were predicted correctly 1–3 months before any radiologic evidence was present. In four cases there had been false-positive results with 99mTc-HEDP while 18F gave always correct information except in cases of soft tissue inflammation. Here both 99mTc-HEDP and 18F ratios were elevated. The early diagnosis of late complications after replacement arthroplasty seems to be possible. The clinical significance, however, is low: only one out of eight patients with manifest infection is still on conservative treatment. Bone imaging should be done to exclude late infection as a cause of pain after total replacement arthroplasty of the hip joint only.

A patient with a muscle hernia in the thigh showed increased muscle uptake of radioactivity during bone imaging using 99mTc-pyrophosphate. The area of excessive accumulation corresponded well to the location and extent of the herniated muscle tissue observed at surgery. Microscopic examination revealed chronic muscle damage, which was assumed to be responsible for the abnormal muscle labelling found in this patient.

This communication reports a presumed increased localization of 99mTc-diphosphonate in a surgical scar 5 months post-op at the site of a medium sternotomy incision. The possible mechanisms for this observation are commented on and a brief review of the observed sites of soft-tissue uptake of 99mTc-labeled bone imaging agents is given.

We present a patient with diffuse and intense uptake in the soft tissues of both lower legs and feet seen on 99mTc-HMDP bone scintigraphy. This finding presumably resulted from compromised blood supply to the lower legs plus a cold environment. The extraosseous bone imaging agent localization was presumably related to an existing ischemic condition that was exacerbated by cold. Differential diagnosis of the scan pattern should be differentiated from the artifact of socks contaminated by radioactive urine.

In a series of 20 patients with a proven diagnosis of myeloma, both full radiographic skeletal surveys and full ratio-nuclide bone images were performed. When these were compared, they showed that (i) imaging underestimated the number of areas involved by 50%, but there were no false negative whole images when compared with the radiology, (ii) large lytic areas on X-ray show as ‘cold’ areas on the bone image but small ones show as normal, (iii) images that show areas of increased uptake (‘hot’) are almost always associated with fracture, and (iv) patients with bone pain very commonly had ‘hot’ images corresponding to the region of pain.