Limitations of quantitative radionuclide bone scanning in the evaluation of total knee replacement.

To establish the value of quantitative radionuclide bone scanning after total knee replacement, 21 patients were scheduled for examination. Eight patients were scanned more than 1 year after surgery (group 1), and 13 within the first postsurgical year (group 2). Ratios were calculated for three regions of interest. The ratio was defined as the counts per pixel for each region of interest, normalized by dividing them by the counts per pixel of the ipsilateral femoral shaft. There was no significant difference in uptake between control subjects and patients in group 2, indicating that the test was not reliable within this time period. No statistical difference was found between the uptake scores in groups 1 and 2, demonstrating that an uninterpretable period of 1 year is perhaps too short. Using a ratio of more than three, seen more than 1 year after surgery as pathologic, a sensitivity of 100%, a specificity of 33%, and an accuracy of 75% was found. Quantitative bone scanning is a very sensitive test for detecting complications, but it is nonspecific in diagnosing loosening of total knee arthroplasties. The value of quantitative scanning presumably lies in the follow-up of patients as an objective method for the evaluation of sequential scanning. Nevertheless, radionuclide data need to be interpreted in correlation with clinical and radiologic findings.

A rare case of sebaceous carcinoma with very malignant characteristics.

A case of a sebaceous carcinoma is presented. This carcinoma of the skin appendages requires diagnosis by histopathology because the clinical appearance is often atypical. Because of the frequency of metastases to local lymph nodes and bone, a careful physical examination and appropriate radiologic/scintigraphic examinations of these organs should be performed routinely. The case presented illustrates the very malignant character of this tumor.

Quantitative scintigraphy of the sacroiliac joints.

The effects of age and laterality on sacroiliac (SI) to sacral indices and ratios were assessed in 62 patients. For the 14 controls, the left mean SI to sacral index was significantly higher than the right one. There was no correlation between age and SI to sacral ratio (= average of right and left index). The mean ratio in 36 patients with sacroiliitis and 12 patients with low back pain was not significantly different from that of the controls, with a clear overlap of indices between controls and sacroiliitis patients.

Clinical usefulness of Tc-99m HMPAO labeled white blood cell imaging in prosthetic vascular graft infections.

The reported frequency of prosthetic vascular graft infections after reconstructive vascular surgery is low. However, it is a serious and potentially catastrophic complication of this treatment, with high morbidity and mortality rates. Effective therapy involves graft excision and replacement. Tc-99m HMPAO labeled leukocyte scintigraphy appears to be an accurate method of detecting prosthetic vascular graft infections. The value of leukocyte scanning is illustrated by two case reports.

Clinical significance of squamous cell carcinoma antigen in cancer of the human uterine cervix. Comparison with CEA and CA-125.

Serum squamous cell carcinoma antigen (SCCa) concentrations were determined by a radioimmunoassay kit before and during the treatment of 50 patients with cervical carcinoma: 44 with squamous cell carcinoma (SCC) and 6 with adenocarcinoma. The positivity rate of SCCa was 50% (52% for SCC and 33% for adenocarcinoma). The sensitivity of SCCa for SCC was twice as high as that of CEA and CA-125. Low serum concentrations were observed in early-stage carcinoma, indicating that SCCa is not useful for diagnosis. In advanced cases, serum levels were directly and significantly correlated with the stage of the disease.

Tc-99m HM-PAO labelled leucocyte scanning for detection of infection in orthopedic surgery.

The use of labelled granulocyte scintigraphy is recognized as a reliable method for detecting osteomyelitis and other skeletal sepsis. Tc-99m hexamethyl propyleneamine oxime (Tc-99m HM-PAO), a lipophilic chelate offers the advantages of availability, lower radiation dose and higher image resolution, compared to other labelling agents. We have scanned 36 orthopedic patients with suspected infection, using autologous granulocytes labelled with Tc-99m HM-PAO. In all cases, scans were compared with clinical, microbiological and/or surgical findings. Sensitivity was 94% and specificity was 80%. We therefore believe that Tc-99m HM-PAO leucocyte scanning provides a useful method for detecting osteomyelitis and other skeletal infections.