Technetium-99m-HMPAO-labeled leukocytes and technetium-99m-labeled human polyclonal immunoglobulin G in diagnosis of focal purulent disease.

To evaluate the usefulness of 99mTc-HMPAO-labeled leukocytes and 99mTc-labeled polyclonal human immunoglobulin G (Technescan HIG) in the diagnosis of focal purulent disease, 31 comparative scintigraphies were done in 30 patients with known or strongly suspected focal infection. Focal purulent disease was the final diagnosis in 19 patients. Technetium-99m-labeled leukocytes showed 16 true-positive, no false-positive, 11 true-negative and 3 false-negative findings. The corresponding figures for 99mTc-labeled HIG were 11, 2, 9 and 8. The sensitivity and specificity of imaging with labeled leukocytes were 84% and 100%, respectively, and with labeled HIG, 58% and 82%, respectively. The overall accuracy of the leukocyte scan was significantly better than that of the HIG scan (90% versus 67%, p < 0.001). Thus, if focal infection is suspected, scintigraphy with 99mTc-labeled leukocytes is the preferable method. No cases exhibited a better imaging result with 99mTc-HIG scintigraphy than with 99mTc-labeled leukocytes.

Arthrography of the biceps tendon.

The purpose of this study was to analyse the factors having an influence on the arthrographic imaging of the biceps tendon. The study comprised 174 patients suffering from chronic shoulder pain. They underwent conventional shoulder arthrography with sodium meglumine metrizoate or metrizamide as a contrast medium. In the patients with a full-thickness tear of the rotator cuff, the biceps tendon sheath failed to fill with contrast medium more often than in those with an intact tendinous cuff. Metrizamide filled the biceps tendon sheath more readily than sodium meglumine metrizoate in patients with a full-thickness tear of the rotator cuff. The volume of the contrast medium injected had no influence on the imaging of the biceps tendon.

Complicated bone and soft-tissue infections. Imaging with 0.1 T MR and 99mTc-HMPAO-labeled leukocytes. ff.

PURPOSE: To assess the value of imaging by 0.1 T MR and by 99mTc-HMPAO-labeled leukocytes in confirming skeletal infection in patients with soft-tissue infections and/or bone pathology. METHODS: Thirty-nine anatomical sites (35 patients) with suspected bone infection were prospectively imaged with 0.1 T MR and 99mTc-HMPAO-labeled leukocytes. Thirty-two infected areas were confirmed: 12 osteomyelitis (out of which 3 were spondylitis) and 27 soft-tissue infections (both bone and soft-tissue infection in 7 areas). RESULTS: MR imaging showed 31 true-positive, 3 true-negative, 4 false-positive and one false-negative diagnosis of infection and scintigraphy 27, 7, 0 and 5 respectively. The sensitivity of MR for osteomyelitis was 100% (12/12) and of scintigraphy 42% (5/12), p<0.01. The specificity of MR and of scintigraphy for osteomyelitis were 81% (22/27) and 93% (25/27) respectively. The sensitivity of MR for soft-tissue infection was 96% (26/27) and specificity 75% (9/12). The correspoding figures for scintigraphy were 85% (23/27) and 100% (12/12). MR and scintigraphy were concordant with respect to the final diagnosis in 28/39 (72%) sites and discordant in 10 (26%). In one patient with Charcot osteoarthropathy a false-positive finding was found by both methods. MR detected all 3 cases of spondylitis, scintigraphy none. Nonpyogenic inflammations and neuroarthropathic joints were indistinguishable from infection by MR. CONCLUSION: Combined imaging with MR and 99mTc-labeled leukocytes is recommended in diagnostically complicated bone infections except for spondylitis where MR is the method of choice. Congruent positive findings are highly suggestive of infection, the extent of which can be determined. Congruent negative results exclude infection.

MR imaging of the lower spine. Differentiation between infectious and malignant disease.

The findings on MR imaging of 28 patients with spinal infection and 40 patients with spinal malignant disease were compared. Spinal infections involved one to 4 vertebrae, usually (23/28) 2 vertebrae. The posterior elements were involved with certainty in 26/40 patients with malignancy but in none with infection. In the latter group, the posterior elements might have been involved in 3/28. The intervertebral disk between the infected vertebrae was involved in 26/28 patients and 21/28 had a paravertebral mass. Spinal malignancies affected the vertebrae alone in 19 patients and paravertebral extension was found in 21/40 patients. The intervertebral disk was involved only in one patient with malignancy. The differences in the distribution of the MR findings between spinal infection and spinal malignancy were highly significant (p < 0.001). The highest signal intensity of the infectious lesions on T2-weighted images was equal to or higher than that of the cerebrospinal fluid (CSF) in 26/28 patients. In contrast, the signal intensity of the malignant lesions was hypointense as compared to the CSF in 29/40 patients (p < 0.001). MR is a useful method for differentiating between infection and malignancy in the lower spine; T2-weighted images are especially valuable for differentiation.

Low-field MR imaging for the assessment of therapy response in musculoskeletal infections.

Fifty-one patients with musculoskeletal infection were imaged by repeated MR imaging at ultra low-field and low-field strength. Soft-tissue infection, osteomyelitis, septic arthritis, and spondylitis were studied. The MR finding was scored according to the signal intensity (SI) on T2-weighted images (T2WI), and correlated with the values of serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and peripheral white blood cell (WBC) count. There was a positive correlation between the MR score and both CRP and ESR, but no correlation between MR score and WBC. The MR score between the follow-up studies decreased significantly in accordance with clinical reconstitution. The MR finding according to the SI on T2WIs corresponded better to disease activity than did the CRP or ESR.

Bone malalignment in acute injuries of the wrist.

The purpose of this study was to analyze radiographic signs of carpal bone instability in patients with an acutely injured wrist. There were 80 patients (52 women and 28 men) with a fall on the outstretched hand. Fifty patients had a fracture of the distal radius, and eight had a scaphoid fracture. The patients with a bone fracture showed a larger scapholunate angle than those without a fracture (P less than 0.001, t-test). However, only four of them showed true carpal bone instability: two patients with a scaphoid fracture and one with a radius fracture had dorsiflexion instability of the wrist and one patient with a radius fracture had dorsal subluxation of the wrist. In addition, one patient without any bone fracture had scapholunate dissociation, one form of carpal bone instability. Although carpal bone instability is not frequent in an acutely injured wrist, its signs should be remembered in the radiographic analysis of the traumatic wrist to prevent subsequent articular disorders.

Detection of soft-tissue and skeletal infections with ultra low-field (0.02 T) MR imaging.

To evaluate the use of ultra low-field (0.02 T) magnetic resonance (MR) imaging in the diagnosis of musculoskeletal infection, MR examinations with T2 weighted sequences were performed in 61 patients thought to be suffering from one of four major diagnostic categories: Soft-tissue abscesses (n = 22), osteomyelitis (n = 21), septic arthritis (n = 9) and spondylitis (n = 9). Infection was confirmed for 37 of these 61 patients. The verified abscesses, arthritis, spondylitis and acute osteomyelitis could be detected by 0.02 T MR. The sensitivity was poor in cases of chronic osteomyelitis. There was one false positive finding in a patient with a possible soft tissue infection. The 0.02 T MR examination failed four times. Two patients were too heavy and another 2 patients had magnetic material in or near the scanning field. Compared with computed tomography and isotope scanning, 0.02 T MR proved a little more informative, but without any statistical significance.