Sequential use of technetium 99m MDP and gallium 67 citrate imaging in the evaluation of painful total hip replacement

Fourteen patients with 20 total hip joint replacements were studied for 14 painful prosthetic hips. Clinical examination, plain film radiographs and 99Tcm-MDP bone scans failed to differentiate between infection and mechanical loosening of a prosthesis. Sequential use of 99Tcm-MDP and 67Ga-citrate bone scans were performed in an attempt to discover underlying infectious process. Increased focal uptake of both radiopharmaceuticals over the same hip indicated an infectious process responsible for prosthetic loosening. There were no false positive gallium examinations. Sequential use of 99Tcm-phosphate compounds and 67Ga-citrate is recommended for differentiation between mechanical loosening of a prosthesis and loosening of a prosthesis secondary to an infectious process.     

FDG-PET, 99mtc-HMPAO white blood cell SPET and bone scintigraphy in the evaluation of painful total knee arthroplasties.

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled white blood cell (WBC) scintigraphy and bone scintigraphy were used in the evaluation of total knee arthroplasties (TKAs). We prospectively included 21 patients who had a three-phase bone scan for exclusion of infection of TKAs. Four hours after injection of 185 MBq 99mTc-HMPAO-labelled WBCs, planar and single-photon emission tomographic (SPET) imaging was performed. Planar imaging was repeated at 24 h p.i. Consecutively images of the knees were obtained with a dedicated PET system 60 min following the injection of 370 MBq of FDG. Focal tracer uptake was scored on SPET and PET visually (0=no uptake, 4=intense uptake). In addition, SUV (standardised uptake value) per voxel was calculated from attenuation-corrected PET images using the MLAA algorithm. Focal uptake at the bone-prosthesis interface was used as the criterion for infection before and after correlation with the third phase of the bone scan. Final diagnosis was based on operative findings, culture and clinical outcome. In the infected TKAs, the WBC scan showed focal activity of grade 2 (n=2), 3 (n=l) or 4 (n=2). PET scan revealed focal activity of grade 4 (n=5) or 3 (n=1). WBC scan alone had a specificity for infection of 53% [positive predictive value (PPV) 42%, sensitivity 100%], compared with 73% for PET scan (PPV 60%, sensitivity 100%). Considering only lesions at the bone-prosthesis interface that were also present on the third phase of the bone scan, we found a specificity of 93% (PPV 83%) for WBC scan. Using these criteria, a specificity of 80% (PPV 67%) was obtained for PET scan. Two out of three false-positive PET scans were due to loosening of the TKA. It is concluded that WBC scintigraphy in combination with bone scintigraphy has a high specificity in the detection of infected TKAs. FDG-PET seems to offer no additional benefit.     

FDG-PET, 99mTc-HMPAO white blood cell SPET and bone scintigraphy in the evaluation of painful total knee arthroplasties

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled white blood cell (WBC) scintigraphy and bone scintigraphy were used in the evaluation of total knee arthroplasties (TKAs). We prospectively included 21 patients who had a three-phase bone scan for exclusion of infection of TKAs. Four hours after injection of 185 MBq ^99mTc-HMPAO-labelled WBCs, planar and single-photon emission tomographic (SPET) imaging was performed. Planar imaging was repeated at 24 h p.i. Consecutively images of the knees were obtained with a dedicated PET system 60 min following the injection of 370 MBq of FDG. Focal tracer uptake was scored on SPET and PET visually (0=no uptake, 4=intense uptake). In addition, SUV (standardised uptake value) per voxel was calculated from attenuation-corrected PET images using the MLAA algorithm. Focal uptake at the bone-prosthesis interface was used as the criterion for infection before and after correlation with the third phase of the bone scan. Final diagnosis was based on operative findings, culture and clinical outcome. In the infected TKAs, the WBC scan showed focal activity of grade 2 (n=2), 3 (n=1) or 4 (n=2). PET scan revealed focal activity of grade 4 (n=5) or 3 (n=1). WBC scan alone had a specificity for infection of 53% [positive predictive value (PPV) 42%, sensitivity 100%], compared with 73% for PET scan (PPV 60%, sensitivity 100%). Considering only lesions at the bone-prosthesis interface that were also present on the third phase of the bone scan, we found a specificity of 93% (PPV 83%) for WBC scan. Using these criteria, a specificity of 80% (PPV 67%) was obtained for PET scan. Two out of three false-positive PET scans were due to loosening of the TKA. It is concluded that WBC scintigraphy in combination with bone scintigraphy has a high specificity in the detection of infected TKAs. FDG-PET seems to offer no additional benefit.     

Diagnosis of osteomyelitis in the presence of soft-tissue infection and radiologic evidence of osseous abnormalities: value of leukocyte scintigraphy

To evaluate the usefulness of 111In-leukocyte scintigraphy for identifying osteomyelitis in the presence of soft-tissue infection, we prospectively studied 45 bone sites adjacent to soft-tissue infection in patients with abnormal findings on radiographs and 99mTc bone scans that were suggestive of osteomyelitis. 111In-leukocyte scans were analyzed in terms of the intensity of abnormal uptake and its location relative to bone. The diagnosis of osteomyelitis was established from results of percutaneous bone biopsy culture (n = 35), histologic examination of surgical specimens (n = 8), and clinical follow-up (n = 2). Osteomyelitis was present at 22 sites, including 16 of 18 sites with increased leukocyte uptake in bone, resulting in a sensitivity of 73%, specificity of 91%, and positive predictive value of 89% for this finding. Osteomyelitis was present at four of 17 sites with predominantly soft-tissue localization of leukocyte activity in the region of bone, none of seven sites with normal leukocyte scans, and two of three sites with diminished leukocyte uptake in bone. Although not helpful in distinguishing infectious from noninfectious bone abnormalities, 3- and especially 24-hr bone scans viewed in conjunction with leukocyte studies provided important correlation to aid in estimating the location of focal abnormal leukocyte uptake. The finding of soft-tissue infection with increased uptake of labeled leukocytes that extends to involve adjacent bone strongly suggests concurrent osteomyelitis. When the presence of abnormal leukocyte uptake in bone is uncertain, additional imaging and possibly biopsy may be required to establish or exclude the diagnosis of osteomyelitis.     

FDG PET for differentiation of infection and aseptic loosening in total hip replacements: comparison with conventional radiography and three-phase bone scintigraphy

PURPOSE: To compare the diagnostic efficacy of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) with that of conventional radiography and three-phase bone scintigraphy in patients suspected of having infection in their total hip replacements. MATERIALS AND METHODS: Thirty-five patients with painful total hip replacements and possible septic prosthetic loosening were examined with FDG PET, conventional radiography, and three-phase bone scintigraphy. PET, radiographic, and scintigraphic images were each evaluated by two independent observers in a blinded fashion. For 32 of 35 patients, serial conventional radiographs were available. Results of microbiologic examinations of surgical specimens represented the standard of reference in 26 patients, and results of joint aspiration plus clinical follow-up of at least 6 months represented the standard of reference in the remaining nine patients. Sensitivity, specificity, accuracy, and interobserver variability (kappa) values were calculated. The imaging modalities were compared in terms of diagnostic confidence by using the sign test. RESULTS: Nine patients had septic and 21 patients had aseptic loosening. In five patients, neither loosening nor infection was confirmed. For diagnosing infection with FDG PET, conventional radiography, and bone scintigraphy, respectively, sensitivity values for reader 1 and reader 2 were 33% and 22%, 89% and 78%, and 56% and 44%, while specificity values were 81% and 85%, 50% and 65%, and 88% and 92% and accuracy values were 69% for both readers, 60% and 69%, and 80% for both readers. PET was significantly more specific (P =.035) but less sensitive (P =.016) than conventional radiography for the diagnosis of infection. CONCLUSION: In a study population of patients suspected of having infected total hip replacements, FDG PET performed similarly to three-phase bone scintigraphy. FDG PET was more specific but less sensitive than conventional radiography for the diagnosis of infection.     

Diagnostic value of lung uptake of indium-111 oxine-labeled white blood cells

One hundred sixty-two white-blood-cell scans were retrospectively reviewed to determine the sensitivity and specificity of the test for pulmonary and pleural infection. All scans were performed 18-24 hr after injection of indium-111 oxine-labeled autologous or donor cells. Pulmonary activity was graded on a scale of 0-4: 0 = equal to soft tissue; 1 = greater than soft tissue but less than rib; 2 = equal or greater than rib but less than liver; 3 = equal or greater than liver but less than spleen; 4 = equal to spleen. Activity was also characterized as being focal or diffuse. The white-blood-cell scan findings were correlated with the clinical diagnosis on the basis of physical examination, laboratory results, chest radiographs, clinical course, and pathologic studies when available. As pulmonary activity increased from grade 1 to 4, sensitivity declined from 93% to 14% and specificity increased from 64% to 100%. The sensitivity and specificity of focal uptake were 31% and 89% vs 62% and 74% for diffuse pulmonary activity. Making a distinction between focal and diffuse activity did not improve the specificity of low grades of pulmonary activity. The white-blood-cell scan can be very sensitive or very specific for pulmonary or pleural infection, depending on the criteria selected for a positive scan.     

Initial results in the assessment of multiple myeloma using 18F-FDG PET

This prospective study was undertaken to investigate the appearance of multiple myeloma on fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET). Furthermore, the accuracy of FDG-PET in detecting myeloma lesions and its influence on patient management were evaluated. Forty-three patients with known multiple myeloma (n=28) or solitary plasmacytoma (n=15) underwent FDG-PET. The results of routinely performed radiographs and of scans obtained using all available imaging modalities (MRI, CT), as well as the clinical course, were used for verification of detected lesions. Focally increased tracer uptake was observed in 38 of 41 known osteolytic bone lesions (sensitivity 92.7%) in 23 patients. In addition, 71 further bone lesions which were negative on radiographs were detected in 14 patients. Twenty-six (36.6%) of these lesions could be confirmed in ten patients. As a result of FDG-PET imaging, clinical management was influenced in five (14.0%) patients. The positive predictive value for active disease was 100% in patients with focal or mixed focal/diffuse skeletal FDG uptake and 75% in patients with diffuse bone marrow uptake. Depending on the interpretation of the PET scans in patients with diffuse bone marrow uptake, the sensitivity ranged from 83.8% to 91.9% and the specificity from 83.3% to 100%. FDG-PET thus proved highly accurate in detecting multiple myeloma, and revealed a greater extent of disease than routine radiographs in 14 of 23 (60.9%) patients who had osteolytic bone lesions. FDG-PET might contribute to the initial staging of solitary plasmacytoma.     

Evaluation of infectious diabetic foot complications with indium-111-labeled human nonspecific immunoglobulin G.

Osteomyelitis of the foot is a well-known complication of diabetes mellitus. In this study, the validity of 111In-labeled human nonspecific immunoglobulin G (IgG) scintigraphy was studied in 16 diabetic patients with foot ulcers, gangrene or painful Charcot joints. In all patients, plain radiographs, conventional bone scan images and 111In-IgG images were recorded. The results were verified by histologic examination of surgical specimens in patients who did not respond to antibiotic treatment within 2-3 wk (10 lesions) or long-term clinical follow-up of at least 6-mo (16 lesions). On the bone scans, all seven osteomyelitic foci were detected. However, 19 additional foci not due to osteomyelitis were seen. The absence of true-negative bone scans in this study resulted in a specificity of 0%. On the plain radiographs, four of seven osteomyelitis foci were detected; for 111In-IgG scintigraphy, six of seven (sensitivity 57% and 86%, respectively). Plain radiographs correctly ruled out osteomyelitis in 15 of 19 lesions, 111In-IgG scintigraphy in 16 of 19 (specificity 79% and 84%, respectively). All imaging procedures gave false-positive results in penetrating ulcers over the calcaneus in two patients and in one patient with a Charcot joint, most likely due to recent fractures. A false-negative 111In-IgG study was observed in a patient with severe arterial angiopathy. Accurate estimation of probable osteomyelitis was not possible from the results of soft-tissue cultures, since in only 6 of 12 positive cultures, osteomyelitic foci could be proven. Indium-111-IgG scintigraphy can contribute to adequate evaluation of osteomyelitis in diabetic foot complications because it improves specificity when compared to bone scan and radiographic findings and improves sensitivity in comparison to plain radiographs.     

Comparison of Tc-99m-labelled antileukocyte fragment Fab' and Tc-99m-HMPAO leukocyte scintigraphy in the diagnosis of bone and joint infections: a prospective study

Between January and July 1998, we conducted a prospective study to compare Tc-99m-labelled antigranulocyte monoclonal antibody fragment Fab' (LEUKOSCAN) scintigraphy versus Tc-99m-hexamethylpropyleneamine oxime (Tc-99m-HMPAO)-labelled leukocyte scintigraphy (HMPAO-LS) for the diagnosis of unselected patients with bone and joint infection. Twenty-three patients (16 men and 7 women; mean age, 67 years) with suspected bone infection were explored successively with bone scintigraphy, HMPAO-LS and LEUKOSCAN scintigraphy. Thirty-two foci were studied (diabetic foot = 11, prosthetic material = 8, joint disease = 4, others = diagnosed in 18 cases, eight on the basis of bacteriological and histological examination of surgical or puncture specimens, with or without radiographic signs, and 10 on the basis of clinical course and radiographic findings. Overall sensitivity, specificity and accuracy were 86%, 72% and 78%, respectively, for LEUKOSCAN scintigraphy (12 true positives (TP), 13 true negatives (TN), 5 false positives (FP), 2 false negatives (FN)), 93%, 100% and 96%, respectively, for HMPAO-LS (13TP, 18TN, 0FP, 1FN), and 100%, 17% and 53.3%, respectively, for bone scintigraphy. In this small series, LEUKOSCAN scintigraphy was found to be less specific for the diagnosis of osteomyelitis than HMPAO-LS. In addition, the interpretation of LEUKOSCAN scintigraphy is more difficult than HMPAO-LS for the diagnosis of bone infection in the diabetic foot, and would appear to be less discriminating for differentiating soft tissue infection from osteitis in the case of plantar perforating ulcers.     

Subacute and chronic bone infections: diagnosis using In-111, Ga-67 and Tc-99m MDP bone scintigraphy, and radiography

The usefulness of indium-111 white blood cell scintigraphy in the diagnosis of subacute or chronic bone infection was examined in 21 orthopedic patients. In-111 WBC imaging was compared with gallium-67 and technetium-99m methylene diphosphonate skeletal scintigraphy and bone radiography, all studies being performed within 1 week. In-111 WBC scintigraphy showed no definite advantage over Ga-67 scintigraphy in the identification of chronic bone infection. The two tests had the same sensitivity (80%) and similar specificity (In-111 WBC 75%, Ga-67 83%; difference not significant). Bone radiography had a sensitivity of 60% and a specificity of 67%. A negative Tc-99m MDP bone scintigram ruled out infection (sensitivity 100%), but because of low specificity (25%), final evaluation required performance of Ga-67 or In-111 WBC scintigraphy.     

Painful pseudarthrosis following lumbar spinal fusion: detection by combined SPECT and planar bone scintigraphy

Twenty-six adult patients more than 6-months post-lumbar spinal fusion were studied. Flexion and extension radiographs showing motion or bone scintigrams showing focal areas of increased activity within the fusion mass were considered positive for pseudarthrosis. Patients were classified as either symptomatic or asymptomatic. Among the 15 symptomatic patients, scintigraphy had a sensitivity of 0.78 and a specificity of 0.83 which was superior to the 0.43 sensitivity and 0.50 specificity of radiography. Six of the 11 asymptomatic patients had focal areas of increased activity in the bony fusion mass, possibly reflecting painless pseudarthrosis. Planar imaging was substantially enhanced by SPECT in 14 of the 26 cases. It is concluded that for the patient who remains symptomatic after lumbar spinal fusion, bone scintigraphy with SPECT is of significant value in detecting painful pseudarthrosis.     

A comparison of iodine-123 meta-iodobenzylguanidine scintigraphy and single bone marrow aspiration biopsy in the diagnosis and follow-up of 26 children with neuroblastoma

In staging neuroblastomas, the demonstration of tumoural invasion of the bone marrow is an important criterion with regard to the therapeutic prospects and the prognosis. Iliac crest aspiration sampling has been used routinely for the detection of bone marrow metastases in neuroblastoma. However, due to the limited character of the sampling, it sometimes leads to false-negative results. Another procedure which is used to determine the extent of neuroblastoma is metaiodobenzylguanidine (mIBG) scintigraphy. In order to establish the respective merits of both diagnostic techniques retrospectively, 148 iodine-123 mIBG scans of 26 children with neuroblastoma have been re-evaluated and compared with the results of routine bone marrow samples obtained within a 4-week period before or after scanning. Three types of mIBG uptake in the bone/bone marrow could be differentiated: (1) no visualization of the skeleton; (2) diffuse uptake in the skeleton with or without focally increased uptake, which indicates massive, diffuse bone marrow invasion by the tumour; and (3) focal tracer accumulation in one or several bones. No tracer uptake was observed in the skeleton in 91 scans. In 89 of the 91 the bone marrow biopsy was negative. Twenty-four scans showed diffuse skeletal uptake with or without foci. The bone marrow biopsies were negative for eight of those 24 scans. Hyperactive foci in one or more bones without diffuse tracer accumulation in the skeleton were detected in 33 scans. In only 7 of these 33 scans did bone marrow biopsy specimens from the iliac MDP crest contain neuroblastoma cells. Available technetium-99m methylene diphosphonate (MDP) whole-body scintigrams were also compared with the corresponding mIBG scans. Thirty-eight mIBG scans showed no visualization of the skeleton; ^99mTc-MDP scintigrams were also normal. Seven patients with diffuse mIBG uptake in the skeleton appeared as normal on the ^99mTc-MDP scans. Among 27 cases showing focal mIBG uptake in the skeleton with or without diffuse uptake, only I8 demonstrated a hot spot on the bone scintigram. The results of our study indicate that for the assessment of bone marrow infiltration by neuroblastoma, 1231-mIBG scintigraphy is more sensitive than the conventional cytological examination of bone marrow smears routinely obtained from the iliac crest, has a very high sensitivity in excluding bone marrow invasion, has a high specificity for detecting bone marrow invasion, appears to be able to detect early tumoural deposits in the bone marrow before osseous invasion occurs as shown on the MDP scans and is superior to ^99mTc-MDP bone scan in detecting bone/bone marrow metastases of neuroblastoma. In patients with a positive mIBG scan in the skeleton, bone marrow biopsy will not yield additional information. Correspondence to: K. Osmanagaoglu     

Prospective study of sequential technetium-99m phosphate and gallium imaging in painful hip prostheses (comparison of diagnostic modalities)

Twenty-two painful hip prostheses were studied prospectively with plain radiography, aspiration and arthrography, Tc-99m phosphate bone imaging, and gallium imaging to evaluate loosening, infection, or both and to compare the accuracy of these modalities. Fifteen prostheses were revised yielding 14 loose femoral and eight loose acetabular components. Five proved to have infected prostheses. Arthrograms, plain radiographs, and bone scans are highly sensitive in detecting loosening of the femoral component. This study confirmed a previous retrospective study in demonstrating that accuracy of diagnosis of an abnormal acetabular component using all four modalities is less than that for the femoral component. In infected prostheses, phosphate bone imaging showed high sensitivity of a pattern that accurately diagnosed all the infected cases, whereas gallium imaging missed one case.     

Painful infection at the site of hip prosthesis: CT imaging

PURPOSE: To prospectively determine the accuracy of computed tomography (CT) in the detection of painful infection at the site of hip prosthesis before surgery. MATERIALS AND METHODS: Helical CT examinations of hip prostheses were prospectively performed before surgery after a standard clinical and radiologic examination of 65 patients. CT scans and conventional radiographs were reviewed for periprosthetic bone abnormalities, and CT scans were reviewed for periprosthetic soft-tissue abnormalities (joint distention, fluid-filled bursae, and fluid collection in muscles and perimuscular fat). Patients subsequently underwent revision arthroplasty within 1 month, and infection was diagnosed in 12 (19%) patients. RESULTS: Infection was detected clinically in 25% of patients. Periprosthetic bone abnormalities did not allow differentiation of infection from complications not related to sepsis, except for periostitis, with 100% specificity but only 16% sensitivity. Soft-tissue findings were accurate for detection of infection, with 100% sensitivity and 87% specificity. Fluid collection in muscles and perimuscular fat had a 100% positive predictive value, and absence of joint distention had a 96% negative predictive value. CONCLUSION: CT is accurate in the diagnosis of painful infection at the site of a hip prosthesis on the basis of soft-tissue findings, whereas periprosthetic bone abnormalities are not useful.     

Arthrographic study of painful total hip arthroplasty: refined criteria

The criteria for a diagnosis of loosening or infection of hip arthroplasties on arthrographic study were further refined by a retrospective review of 178 arthrograms representing 170 patients. The 97 arthroplasties that were surgically evaluated form the basis of this report. With the refined criteria, subtraction arthrography had a sensitivity of 96% and specificity of 92% for demonstrating loosening of the femoral component and a sensitivity of 97% and a specificity of 68% for demonstrating loosening of the acetabular component. Pseudocapsule size and the presence of bursae were important factors influencing arthrographic interpretation. Arthrographic findings of pseudocapsule irregularity and the presence of nonbursal cavities were suggestive of infection but were not sensitive or specific. Laboratory evaluation of aspirated material was a more reliable predictor of infection, although its sensitivity was only 71%.     

Immunoscintigraphy with antigranulocyte monoclonal antibodies for the diagnosis of septic loosening of hip prostheses

To determine the value of immunoscintigraphy (IS) with antigranulocyte monoclonal antibodies (Mab) in the diagnosis of subacute or chronic infection of hip prostheses, we prospectively studied 57 patients (23 women and 34 men; age 29–92 years, mean 72.7 years) sent to our institution in the past 6 years for clinical suspicion of septic loosening of a hip prosthesis. Nineteen patients had bilateral prostheses and one of them was studied twice. A total of 78 prostheses were examined. All patients had three-phase bone scans followed by IS with technetium-99m antigranulocyte Mab BW 250/183. Intervals between bone scans and IS varied from 2 days to 4 weeks. Final diagnosis was assessed by culture in 48 cases (articular puncture or intraoperative sampling) and by clinical follow-up of at least 8 months in 30 cases. Twelve prostheses were considered septic and 66 non-septic. The overall sensitivity and specificity were 92% and 64% respectively for bone scans, 67% and 75% for IS and 67% and 84% for both modalities together. In three cases, IS was doubtful and the final clinical diagnosis was negative for infection. False-positive results were observed in the presence of massive loosening of the prosthesis or in association with metaplastic peri-articular bone formation. In three of the four false-negative results, infection was proven only after enrichment of the culture, and the bacterium wasStaphylococcus epidermidis. In 12/33 (36%) positive bone scans IS allowed the diagnosis of infection to be excluded. Overall accuracy of both modalities together was 81% and the negative predictive value was 93%, which compares favourably with the results reported for other non-invasive methods.     

The use of [18 F]fluorodeoxyglucose positron emission tomography to differentiate between synovitis,loosening and infection of hip and knee prostheses

Pain is a common unspecific symptom in orthopaedic prosthetics. The accurate differentiation between synovitis, loosening or infection is often difficult with conventional X-rays, arthrography or bone scintigraphy. Because of the high glucose uptake of inflammatory cells, [18F]fluorodeoxyglucose (18F-FDG) is an appropriate tracer for the evaluation of suspected inflammation or infection. In this preliminary study we describe 18F-FDG PET findings in patients referred for evaluation of painful hip or knee prostheses. We studied 23 patients with 28 prostheses, 14 hip and 14 knee prostheses, who had a complete operative or clinical follow-up. 18F-FDG PET scans were obtained with an ECAT EXACT HR+ PET scanner. High glucose uptake in the bone prostheses interface was considered as positive for infection, an intermediate uptake as suspect for loosening, and uptake only in the synovia was considered as synovitis. The imaging results were compared with operative findings or clinical outcome. PET correctly identified three hip and one knee prostheses as infected, two hip and two knee prostheses as loosening, four hip and nine knee prostheses as synovitis, and two hip and one knee prostheses as unsuspected for loosening or infection. In three patients covered with an expander after explantation of an infected prosthesis PET revealed no further evidence of infection in concordance with the clinical follow-up. PET was false negative for loosening in one case. Our preliminary results suggest that FDG PET could be a useful tool for differentiating between infected and loose orthopaedic prostheses as well as for detecting only inflammatory tissue such as synovitis.     

67Ga whole-body scintigraphy in the evaluation of head and neck squamous cell carcinoma.

The diagnostic accuracy of 67Ga-citrate whole-body scintigraphy for the evaluation of primary tumours, local recurrences, cervical node metastases and distant metastases was investigated in patients with head and neck squamous cell carcinoma (SCC). Altogether, 102 67Ga-citrate whole-body scans were performed on 83 patients with head and neck SCC using a dual-headed gamma camera. The results were compared with those of computed tomography (CT) and final diagnosis. 67Ga scintigraphy correctly diagnosed 28 of 29 primary lesions, a sensitivity of 97% (CT = 97%). For tumour recurrence, 67Ga scintigraphy correctly diagnosed 13 of 15 recurrences and 53 of 58 instances of no recurrence, giving a sensitivity of 87% and a specificity of 91% (CT = 80 and 62%, respectively). Scintigraphy correctly diagnosed 23 of 31 metastatic sides of the neck and all 173 negative sides of the neck, giving a sensitivity of 74% and a specificity of 100% (CT = 90 and 84%, respectively). Finally, scintigraphy correctly diagnosed all 12 distant metastases as well as 86 of 90 cases of no metastasis, resulting in a sensitivity of 100% and a specificity of 96%. Furthermore, in five patients, distant metastases were initially detected on 67Ga scintigraphy. In conclusion, 67Ga whole-body scintigraphy with a dual-headed camera resulted in a high sensitivity and specificity for the detection of primary lesions, recurrences and distant metastases of head and neck SCC. Although the sensitivity for detecting neck node metastases was relatively low, the specificity was high. Thus, 67Ga scintigraphy is an effective technique for the evaluation of head and neck SCC, especially tumour recurrence and distant metastases.     

Role of nuclear medicine in diagnosis of the infected joint replacement.

Some complications of joint replacement surgery are easily diagnosed; however, differentiating infection from aseptic loosening is difficult because these entities are remarkably similar at clinical and histopathologic examination. Clinical signs and symptoms, laboratory tests, radiography, and joint aspiration are insensitive, nonspecific, or both. Cross-sectional imaging modalities are hampered by artifacts produced by the prosthetic devices themselves. Radionuclide imaging is not affected by the presence of metallic hardware and is therefore useful for evaluating the painful prosthesis. Bone scintigraphy is useful as a screening test, despite an accuracy of only 50%-70%, because normal results essentially exclude a prosthetic complication. The addition of gallium-67, a nonspecific inflammation-imaging agent, improves the accuracy of bone scintigraphy to 70%-80%. The accuracy of combined leukocyte-marrow imaging, 90%, is the highest among available radionuclide studies. Its success is due to the fact that leukocyte imaging is most sensitive for detection of neutrophil-mediated inflammation (ie, infection). The success of leukocyte-marrow imaging is tempered by the limitations of in vitro labeling. In vivo labeling has been investigated, and a murine monoclonal antigranulocyte antibody appears promising. Some investigations have focused on fluorodeoxyglucose imaging. Although this method is sensitive, specificity is a concern.