Osteomyelitis

The use of 111In-labelled granulocyte scintigraphy is recognized as a reliable method for detecting osteomyelitis and has similar sensitivity and significantly increased specificity compared to bone scintigraphy and 67Ga studies. Recent published work using pure granulocytes labelled with 111In tropolonate to detect osteomyelitis resulted in sensitivity of 100% and specificity of 92%. 99Tcm as an alternative granulocyte label offers advantages of convenience, lower radiation dose and higher image resolution. We have scanned 20 patients with suspected osteomyelitis using autologous granulocytes labelled with 99Tcm hexamethylpropyleneamineoxime (HMPAO), 12 of whom had prosthetic joints. The scan results were correlated with clinical, radiographic, microbiological and histological findings. Sensitivity was 100% and specificity was 93% which compares favourably with results obtained using 111In-labelled granulocytes. We believe that labelled granulocyte scintigraphy is a useful investigation in the diagnosis of osteomyelitis and that 99Tcm HMPAO appears to be at least as useful as 111In as the labelling agent.     

Evaluation of a 3-hour indium-111 leukocyte image as a surrogate for a technetium-99m nanocolloid marrow scan in the diagnosis of orthopedic infection

OBJECTIVES: This is a retrospective study to evaluate a 3-hour In-111-labeled leukocyte image as a surrogate for a Tc-99m nanocolloid marrow scan in the investigation of suspected orthopedic infection using In-111 leukocyte scintigraphy. METHODS: Images from 51 patients who had received contemporaneous In-111-labeled leukocyte scintigraphy and Tc-99m nanocolloid marrow scintigraphy were reviewed. Initially, the 3-hour and 22-hour In-111-labeled leukocyte images were compared. Sites of abnormal uptake on the 22-hour image were correlated with the 3-hour image and were graded according to the level of concordance or discordance. One week later, the Tc-99m nanocolloid images and 22-hour In-111-labeled leukocyte images of the same patients were compared and graded for concordance or discordance. When discrepancies in grading arose between the observers, a consensus opinion was achieved after additional review of the images a week later. RESULTS: On inspection of the 22-hour In-111 leukocyte images, 93 sites of focal, potentially abnormal leukocyte accumulation were identified. When the grading system was reduced to simply "concordant" or "discordant," there was good agreement between the observers in the majority of cases, with kappa statistics 0.77 for Tc-99m nanocolloid versus 22-hour In-111-labeled leukocyte images and 0.78 for 3-hour versus 22-hour In-111-labeled leukocyte images. Using the comparison of the Tc-99m nanocolloid marrow scan and the 22-hour In-111-labeled leukocyte images to identify concordance or discordance as the "gold standard" for scintigraphic evaluation of suspected orthopedic infection, comparison of the 3-hour In-111-labeled leukocyte images with the 3-hour In-111-labeled leukocyte images gave a sensitivity of 77%, a specificity of 77%, and an accuracy of 77%. CONCLUSIONS: A 3-hour image is helpful using In-111-labeled leukocyte scintigraphy.     

99Tcm and 111In leucocyte scintigraphy in inflammatory bowel disease.

A comparative study of 99Tcm-hexamethylpropyleneamine oxime (HMPAO) and 111In leucocyte scintigraphy was performed in inflammatory bowel disease. Two hundred and thirty-four patients were studied, 146 had 99Tcm-HMPAO, 82 had 111In and six had both. The sensitivity, specificity and accuracy of the 99Tcm leucocyte scan were 96, 97 and 97%, respectively, and 96, 97 and 97%, respectively, for the 111In leucocyte scan. 99Tcm-HMPAO leucocytes demonstrated similar diagnostic accuracy to 111In-labelled leucocytes with improved image quality and reduced radiation dose.     

99Tcm-HMPAO labelled leucocytes: comparison with 111In-tropolonate labelled granulocytes

The lipophilic complex, 99Tcm-hexamethylpropyleneamine oxime (HMPAO) is an efficient leucocyte label, and labels granulocytes with more stability than mononuclear leucocytes. The recovery of 99Tcm-HMPAO granulocytes, expressed as the percentage of injected granulocyte-associated activity circulating as granulocyte-associated activity 40-45 min after injection, was 37% (S.E. 3%), similar to the recovery of 111In-labelled granulocytes isolated and labelled in plasma using tropolone. The T1/2 of 99Tcm-HMPAO labelled granulocytes in blood was 4.4 h (S.E. 0.4 h), less than that of 111In-labelled granulocytes, although when a correction was made for 99Tcm elution, it was 6.4 h. The initial biodistribution of 99Tcm-labelled leucocytes was similar to 111In-labelled granulocytes, with a rapid initial lung transit, prominent splenic activity, bone marrow activity and minimal hepatic activity, although, unlike 111In, 99Tcm activity was also seen in urine, occasionally in the gallbladder, and, from about 4 h, consistently in the colon. Bone marrow activity was particularly prominent with 99Tcm. About 6% of 99Tcm was excreted in the faeces up to 48 h after injection, and about 17% in urine up to 24 h. The time-activity curves of reticuloendothelial activity up to 24 h were broadly similar for the two labelled cell preparations, and the differences that were observed can be explained on the basis of a higher rate of 99Tcm elution. Clinical information given by the two agents was similar in 27 of 30 patients who received both. Of the three who gave different information, one received 111In-labelled granulocytes which were considered to be functionally suboptimal and two, with inflammatory bowel disease, showed different distributions of abnormal bowel activity. We conclude that with respect to granulocyte kinetics and clinical data, 99Tcm-HMPAO labelled leucocytes are comparable with 111In-tropolonate labelled granulocytes.     

Clinical validation of the avidin/indium-111 biotin approach for imaging infection/inflammation in orthopaedic patients.

We report here the results of a validation study of the avidin/indium-111 biotin approach in patients with skeletal lesions. This study involved 54 patients with orthopaedic conditions: 20 patients with intermediate suspected osteomyelitis of the trunk, 19 patients with infection/inflammation of prosthetic joint replacements, and 15 patients with suspected osteomyelitis of appendicular bones. Avidin (3 mg) was injected as an i.v. bolus, followed 4 h later by 111In-biotin; imaging was acquired 30 min and 16-18 h after administration of 111In-biotin. Technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO)-labelled leucocyte scintigraphy was performed in 39/54 patients. The overall sensitivity of the avidin/111In-biotin scan was 97.7% (versus 88.9% for 99mTc-HMPAO leucocyte scintigraphy). While the diagnostic performance of avidin/111In-biotin scintigraphy was similar to that of 99mTc-HMPAO leucocyte scintigraphy in patients with prosthetic joint replacements or osteomyelitis of appendicular bones, the avidin/111In-biotin approach clearly performed better than 99mTc-HMPAO leucocyte scintigraphy in patients with suspected osteomyelitis of the trunk (100% sensitivity, specificity and accuracy versus 50% sensitivity, 100% specificity and 66.7% accuracy for 99mTc-HMPAO-leucocyte scintigraphy). These results demonstrate the feasibility of the avidin/111In-biotin approach for imaging sites of infection/inflammation in the clinical setting. Although no systematic advantages of avidin/111In-biotin scintigraphy were found versus 99mTc-HMPAO leucocyte scintigraphy, the newer scintigraphic method is more practicable and involves lower biological risk for the operators.     

Clinical validation of the avidin/indium-111 biotin approach for imaging infection/inflammation in orthopaedic patients

We report here the results of a validation study of the avidin/indium-111 biotin approach in patients with skeletal lesions. This study involved 54 patients with orthopaedic conditions: 20 patients with intermediate suspected osteomyelitis of the trunk, 19 patients with infection/inflammation of prosthetic joint replacements, and 15 patients with suspected osteomyelitis of appendicular bones. Avidin (3 mg) was injected as an i.v. bolus, followed 4 h later by ¹¹¹In-biotin; imaging was acquired 30 min and 16–18 h after administration of ¹¹¹In-biotin. Technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO)-labelled leucocyte scintigraphy was performed in 39/54 patients. The overall sensitivity of the avidin/¹¹¹In-biotin scan was 97.7% (versus 88.9% for ^99mTc-HMPAO leucocyte scintigraphy). While the diagnostic performance of avidin/¹¹¹In-biotin scintigraphy was similar to that of ^99mTc-HMPAO leucocyte scintigraphy in patients with prosthetic joint replacements or osteomyelitis of appendicular bones, the avidin/¹¹¹In-biotin approach clearly performed better than ^99mTc-HMPAO leucocyte scintigraphy in patients with suspected osteomyelitis of the trunk (100% sensitivity, specificity and accuracy versus 50% sensitivity, 100% specificity and 66.7% accuracy for ^99mTc-HMPAO-leucocyte scintigraphy). These results demonstrate the feasibility of the avidin/¹¹¹In-biotin approach for imaging sites of infection/inflammation in the clinical setting. Although no systematic advantages of avidin/¹¹¹In-biotin scintigraphy were found versus ^99mTc-HMPAO leucocyte scintigraphy, the newer scintigraphic method is more practicable and involves lower biological risk for the operators. Received 9 November 1998 and in revised form 1 February 1999     

Comparison of 99Tcm-HMPAO and 111In-oxine labelled granulocytes in man: first clinical results

The in vitro and in vivo behaviour of 99Tcm-HMPAO (hexamethylpropyleneamineoxime) (n = 12) and 111In-oxine (n = 11) labelled granulocytes, isolated by density-gradient centrifugation (Metrizamide/plasma gradients), was compared in patients with suspected inflammatory diseases. The in vitro elution of both labels and the viability of the labelled cells (99Tcm, 98.5%; 111In, 96.5%) was comparable but the labelling efficiency was different (99Tcm, 44 +/- 13%; 111In, 72.5 +/- 5.5%). In vivo, the lung (t1/2 max: 7.7 min), liver and spleen perfusion patterns were nearly identical; the image quality for detail in 99Tcm scans was superior to 111In images. The blood disappearance curves of 99Tcm and 111In were comparable. In the small number of patients examined all infections could be diagnosed correctly, without false-positive or false-negative results. Disadvantageous is the renal excretion of 99Tcm complexes (3+% over 20 h) with kidney and bladder activity from the beginning of the study. The biliary excretion in half of the patients (n = 6) with unspecific positive small and large bowel visualization and the late intestinal excretion also render the diagnosis more difficult. The recommended best imaging times for abdominal and retroperitoneal inflammations are 30 min to 2 h after injection. Late scans in septic prosthetic joints have disproportionate long acquisition times. As a potential cell labelling compound, 99Tcm-HMPAO has a promising future in comparison to 111In scans because of the good availability of 99Tcm, the image quality and the lower radiation exposure to the patient when lower activities for the early diagnosis of abdominal inflammatory diseases are reinjected.     

99Tcm-nanocolloid imaging in inflammatory bowel disease

We have used 99Tcm-labelled nanocolloid in an attempt to locate areas of inflamed bowel wall or abscesses in five patients with ulcerative colitis and nine with Crohn's disease. The scintigraphic findings were evaluated by comparison with those of recent barium studies and, in three patients, with surgical findings at laparotomy. It proved difficult to localize segments of inflamed bowel accurately with 99Tcm-nanocolloid because of the accumulation of radioactivity in the gut lumen, especially 2 or more hours after injection. However, there was little uptake of the labelled nanocolloid by areas of inflamed gut wall in the period before 2 h. When 99Tcm-nanocolloid scans were compared with 111In-WBC scans in eight patients who had both investigations, 99Tcm-nanocolloid scintigraphy was considerably less sensitive than 111In-WBC scintigraphy. One abscess was located correctly; the other was obscured by nearby bladder and bone marrow radioactivity. We conclude that 99Tcm-nanocolloid scanning is neither sensitive nor reliable enough for assessing the location of inflamed bowel wall or the presence of abscess in patients with inflammatory bowel disease.     

Bone marrow scintigraphy in the diagnosis of post-traumatic avascular necrosis of bone

A series of 19 patients, who were clinically suspected of developing avascular necrosis of bone following fracture, were entered into a pilot study comparing the use of bone marrow scintigraphy with conventional skeletal scintigraphy. Two-phase bone scintigraphy, using 600 MBq of 99Tcm-HMDP, and perfusion and late-phase nanocolloid scintigraphy, using 370 MBq of 99Tcm-nanocolloid, were performed on each patient. In both methods, photon deficiency at the site of interest was taken to indicate avascularity. The perfusion phase of both methods was found to be unhelpful. Agreement between methods was obtained in 18 patients (95%). Six patients had abnormal nanocolloid scans, one of which was normal on the conventional bone scintigram. The remaining 13 patients had no evidence to suggest avascularity in either method. Three of the patients with abnormal scans have had hip replacement surgery following which avascularity of the femoral head was confirmed. 99Tcm-nanocolloid scintigraphy is thus shown to be a very sensitive method of demonstrating avascularity of bone following trauma.     

A prospective comparison of 99mTc-labeled polyclonal human immunoglobulin and 111In granulocytes for localization of inflammatory bowel disease.

There is a need for an easily prepared radiopharmaceutical agent for the detection of inflammation and infection. In a group of 14 patients with inflammatory bowel disease (IBD), the detection of actively involved intestinal segments by nonspecific human polyclonal immunoglobulin (IgG) labeled with 99mTc was compared with that of 111In granulocytes. To determine the specificity of 99mTc-IgG scintigraphy, 8 control patients without clinical indications of intestinal inflammation were examined. 99mTc-IgG was found in the left colon in 8 and in the right colon in 7 of the 8 controls 4 hours after the injection. At that time of scintigraphy only 4 IBD patients exhibited a more intense accumulation at the site of the intestinal segments with active disease. In contrast, in a randomized comparison with 111In granulocytes scintigraphy was positive in 11 patients with the latter technique. Moreover, fewer diseased segments were seen in the 4 patients with positive 99mTc-IgG scintigraphy (6 versus 12 with 111In granulocytes). In view of the low sensitivity and specificity, it is concluded that 99mTc-IgG is not suitable for the scintigraphic staging of IBD patients.     

Comparison of In-111 granulocytes and Tc-99m albumin colloid for bone marrow scintigraphy by the use of quantitative SPECT imaging

A comparison of In-111 oxinate labeled autologous granulocytes and Tc-99m albumin colloid for bone marrow scintigraphy is reported. The aim of this report was to determine if the intense uptake in the liver and spleen with nano-sized colloids, which hampers the evaluation of the skeletal parts surrounding the liver, is reduced by the use of radiolabeled granulocytes. This study is based on a retrospective analysis of 19 abdominal tomographic examinations with In-111 granulocytes performed to detect septic foci. After correction for attenuation and scattering of photons was performed, the uptake in the bone marrow of the lumbar spine was seen to be related to the liver, spleen, and tissue background activity. The results in this study were compared with corresponding data from 20 normal liver/spleen tomographic examinations performed with Tc-99m nanocolloid, which is routinely used for bone marrow scintigraphy. The bone marrow/liver activity ratio for granulocytes varied, but it exceeded the corresponding mean ratio for colloid in all examinations. The mean values for granulocyte uptake 3 and 20 hours after injection was, respectively, about 6 and almost 10 times higher than were those for colloid. The activity ratios between bone marrow and spleen as well as between bone marrow and tissue background was not improved and or may even have been reduced by the use of granulocytes. It is suggested that granulocytes labeled in vitro by Tc-99m hexamethylpropylene amineoxime (HMPAO) or in vivo by monoclonal antigranulocyte antibodies may provide techniques for improved bone marrow imaging.     

Evaluation of white cell scintigraphy using indium-111 and technetium-99m labelled leucocytes

Indium-111 oxine labelled leucocyte (¹¹¹In oxine leucocyte) scintigraphy is the test of choice in detecting occult infection and localising focal inflammation. ¹¹¹In oxine labelling is technically difficult and expensive and leucocyte labelling with technetium-99m stannous colloid (^99mTc Sn colloid) has been considered to be an alternative. Leucocytes from 40 cases referred for investigation of occult infection or localisation of inflammation were simultaneously labelled with ¹¹¹In oxine and ^99mTc Sn colloid with dual isotope acquisition performed at 1, 3 and 24 h. Twenty-four hour ^99mTc Sn colloid scans were corrected for ¹¹¹In downscatter. Each case was independently interpreted by two experienced observers. Twentyone patients demonstrated positive ¹¹¹In oxine leucocyte scans. Using ¹¹¹In oxine leucocyte scans as the gold standard, ^99mTc Sn colloid leucocyte scanning had an overall sensitivity of 86% and a specificity of 95%. Clinical follow-up verified that three patients had false negative ^99mTc Sn colloid leucocyte scans and one patient had a false positive. Further clinical evaluation of ^99mTc Sn colloid labelled leucocytes is required before they can become a reliable replacement for ¹¹¹In oxine leucocytes. Correspondence to: S. Boyd     

Utility of 111In-labelled leucocyte scintigraphy in patients with fever of unknown origin in an era of changing disease spectrum and investigational techniques

BACKGROUND: (111)In-labelled leucocyte, imaging is often used to investigate patients with fever of unknown origin (FUO). Its diagnostic performance, however, has been variable and a broad range of sensitivities and specificities have been reported. The purpose of this investigation was to evaluate the usefulness of (111)In-labelled leucocytes scintigraphy in the detection of a cause of FUO in the light of a changing spectrum of diseases causing it and advances in investigational techniques. MATERIALS AND METHODS: Sixty-one patients with a clinical diagnosis of FUO underwent whole-body (111)In-troponolate-labelled leucocyte scintigraphy in our department over a 2-year period between February 2004 and February 2006. Of these, 54 patients were retrospectively reviewed to identify a cause of FUO. Other parameters such as C-reactive protein (CRP), leucocyte count and radiological findings were also evaluated. RESULTS: Leucocyte scintigraphy was found to be true positive in 12 patients, true negative in 24 patients, false positive in 10 patients and false negative in eight patients. The overall sensitivity of scintigraphy was 60%, specificity 71%, positive predictive value 55%, and negative predictive value 75%. There was no difference in the scintigraphic sensitivity between patients with spontaneous FUO and those with post-operative FUO although the latter showed a higher specificity and PPV. CRP and leucocyte count did not differ significantly between patients with true positive and true negative scintigrams. Overall, 83% of patients with abnormal radiological examinations had positive findings on scintigraphy and 87% of patients with negative findings on radiology had normal scintigraphy. CONCLUSION: Despite changes in disease spectrum and advances in investigational techniques, our results suggest that (111)In-leucocyte scintigraphy is still a useful technique in establishing the cause of FUO. A higher PPV of this test in post-operative situations makes it especially applicable in this category of patients. Equally, the higher NPV in patients with spontaneous FUO virtually excludes infection/inflammation. Finally, a higher pre-test probability based on the radiological tests seems to be important in the optimal use of leucocyte imaging.     

99Tcm(v)-DMSA planar scintigraphy: does it have a role in the management of patients with head and neck squamous carcinoma?

99Tcm(v)-DMSA is a new tumour-imaging agent which has recently been proposed as a scintigraphic marker for head and neck squamous cell carcinoma (SCC). Seventy-seven patients were studied prospectively, of whom 58 had a history and diagnosis of head and neck SCC. All patients were examined, imaged using 99Tcm(v)-DMSA planar scintigraphy and then followed up clinically. In addition, 35 patients were followed up with scintigraphy (81 studies). Scintigraphy was less sensitive and less accurate than clinical examination for the overall detection of patients with SCC, for the detection of patients with SCC at presentation and for the detection of patients with primary tumours, possible nodal disease and with residual and recurrent disease following surgery and irradiation. Approximately 50% of patients exhibited positive uptake of 99Tcm(v)-DMSA in the salivary glands following radiotherapy. Although 99Tcm(v)-DMSA is accumulated at sites of head and neck SCC, its inability to detect low volume disease and apparent low specificity following surgery and irradiation means it has no role to play in the routine evaluation of patients with head and neck SCC.     

Evaluation of metastatic bone disease with pentavalent 99Tc(m)-dimercaptosuccinic acid: a comparison with whole-body scanning and 4/24 hour quantitation of vertebral lesions

The aim of this study was to establish the value of 99Tcm(V)-DMSA scintigraphy in the detection of metastatic bone lesions and compare the results to 99Tcm-MDP bone scintigraphy. Thirty-four patients presenting with metastatic bone disease (Group 1) and 12 controls with degenerative skeletal lesions (Group 2) were studied. Conventional bone scanning and 99Tcm(V)-DMSA whole-body scanning were performed on all patients. All scans were interpreted visually. Furthermore, lesion-to-normal bone ratios (L/N) in vertebral metastases on the 4 and 24 h bone scans were obtained in 58 lesions of cancer patients and in 23 benign (degenerative) vertebral lesions of the control group. 99Tcm-MDP L/N ratios at 24 h (3.08 +/- 0.32) were significantly higher than those at 4 h (2.48 +/- 0.24) in the malignant foci (P < 0.001). No significant difference was observed in benign lesions (P > 0.05). In 167 (164 metastatic, 3 traumatic) of 186 99Tcm-MDP positive lesions (90%) of Group 1, 99Tcm(V)-DMSA uptake was observed. The remaining 19 lesions (10%) were 99Tcm(V)-DMSA negative. Fourteen of these 19 sites were diagnosed as benign. The remaining five foci were malignant. In four lung cancer metastases showing no 99Tcm-MDP uptake, 99Tcm(V)-DMSA uptake was observed. There was no 99Tcm(V)-DMSA accumulation in any of the 99Tcm-MDP positive degenerative lesions of Group 2. All quantitatively evaluated (n = 42) vertebral metastatic foci and two compression fractures in Group 1 showed 99Tcm(V)-DMSA accumulation and an increased 99Tcm-MDP L/N ratio at 24 h. A total of 36 degenerative lesions (Groups 1 and 2) and one compression fracture (Group 1) showed neither 99Tcm(V)-DMSA uptake nor an increased 99Tcm-MDP L/N ratio at 24 h. Our results indicate that quantitative 4/24 h analysis of vertebral lesions on 99Tcm-MDP scans has a similar diagnostic value to 99Tcm(V)-DMSA imaging in the detection of bone metastases. However, the accumulation of 99Tcm(V)-DMSA in four lung cancer metastases showing no 99Tcm-MDP uptake is encouraging and justifies further research in patients with proven bone metastases and negative bone scans.     

Radiation dose rates from adult patients undergoing nuclear medicine investigations

Adult patients undergoing nuclear medicine investigations may subsequently come into close contact with members of the public and hospital staff. In order to expand the available dosimetry and derive appropriate recommendations, dose rates were measured at 0.1, 0.5 and 1.0 m from 80 adult patients just before they left the nuclear medicine department after undergoing one of eight 99Tcm studies, an 123I thyroid, an 111In leucocyte or a 201Tl cardiac scan. The maximum departure dose rates at these distances of 150, 30 and 7.3 microSv h-1 were greater than those found in similar published studies of adult and paediatric patients. To limit the dose to an infant to less than 1 mSv, an 111In leucocyte scan is the only investigation for which it may be necessary to restrict close contact between the infant and a radioactive parent, depending on the dose rate near the surface of the patient, the parent's habits and how fretful is the infant. It is unlikely that a ward nurse will receive a dose of 60 microSv in a working day if caring for just one radioactive adult patient, unless the patient is classified as totally helpless and has undergone a 99Tcm marrow, bone or brain scan. The data and revised calculations of effective exposure times based on a total close contact time of 9 h in every 24 h period should allow worst case estimates of radiation dose to be made and recommendations to be formulated for other circumstances, including any future legislative changes in dose limits or derived levels.     

Prospective investigation of radiologic methods in the diagnosis of intra-abdominal abscesses

A prospective investigation of conventional abdominal radiography, ultrasonography, computed tomography and 111In-labelled leucocyte scintigraphy was performed in 40 patients suspected of having an intra-abdominal abscess. There were 23 confirmed abscesses in the material. When conventional abdominal radiography indicated an abscess, such a lesion was usually present. The ability of abdominal radiography to exclude an abscess was, however, low. Both ultrasonography and 111In-labelled leucocyte scintigraphy detected 65 to 85 per cent of the confirmed abscesses, but both also revealed many abscess-like areas in patients where no unequivocal abscess was confirmed at follow-up. Computed tomography was, when employed as a single method, the most reliable one both to show and to exclude an abscess, However, the combination of ultrasonography and 111In-labelled leucocyte scintigraphy disclosed all the lesions demonstrated by any one of the four methods used in the investigation.     

Indium labelled leucocyte scintigraphy in occult infection: a comparison with ultrasound and computed tomography

A review of five year's experience of the use of 111Indium labelled leucocyte scintigraphy (111In WBC) in the investigation of suspected sepsis is presented. The results of 257 111In WBC scans for which a definitive diagnosis was subsequently established were available for analysis. The findings are compared with those of ultrasound (130 cases) and computed tomography (82 cases) and the final clinical outcome. The sensitivity and specificity of the 111In WBC for the series were 97% and 91% respectively. The major cause of the false positive 111In WBC results was activity within the bowel not due to infection. Thrombus within the inferior vena cava caused a false positive 111In WBC result: this is previously undescribed. There were a large number of incorrect ultrasound results, particularly with abdominal and pelvic abscesses, pyelonephritis, peritonitis and non-infected fluid collections, showing that a negative ultrasound cannot exclude infection. The relative merits of the three modalities are discussed, emphasizing that more than one technique may be required to establish a diagnosis.     

Rectilinear scanning in the detection of acute myocardial infarction.

Myocardial scintigraphy with phosphate bone scanning agents is a new and very useful development in the detection of acute myocardial infarction. Initial experience using a rectilinear scanner is described in 50 consecutive patients admitted to hospital because of suspected myocardial infarction. The routine dose was 15 mCi/5 mg, 99Tcm stannous pyrophosphate intravenously with anterior, left anterior oblique, and lateral scans obtained 45-90 minutes after injection. There was only one false negative scan in 17 patients with proven acute myocardial infarction and that was 16 days after onset. There was no proven false positive investigation in seven patients in which fresh myocardial infarction could be definitely excluded, or in a further 11 cases in which it could be excluded with reasonable confidence. Myocardial scintigraphy was considered helpful in resolving the diagnostic problem in 27 out of 29 equivocal cases. It is concluded that myocardial scintigraphy with a rectilinear scanner is a highly accurate and safe procedure in the detection of acute myocardial infarction. The optimum scanning time is two to six days after onset of suspected infarction, when a diagnostic accuracy approaching 100 per cent can be expected.     

Detection of occult infection following total joint arthroplasty using sequential technetium-99m HDP bone scintigraphy and indium-111 WBC imaging

Preoperative exclusion or confirmation of periprosthetic infection is essential for correct surgical management of patients with suspected infected joint prostheses. The sensitivity and specificity of [111In]WBC imaging in the diagnosis of infected total joint prostheses was examined in 28 patients and compared with sequential [99mTc]HDP/[111In]WBC scintigraphy and aspiration arthrography. The sensitivity of preoperative aspiration cultures was 12%, with a specificity of 81% and an accuracy of 58%. The sensitivity of [111In]WBC imaging alone was 100%, with a specificity of 50% and an accuracy of 65%. When correlated with the bone scintigraphy and read as sequential [99mTc]HDP/[111In]WBC imaging, the sensitivity was 88%, specificity 95%, and accuracy 93%. This study demonstrates that [111In]WBC imaging is an extremely sensitive imaging modality for the detection of occult infection of joint prostheses. It also demonstrates the necessity of correlating [111In]WBC images with [99mTc]HDP skeletal scintigraphy in the detection of occult periprosthetic infection.