Imaging of abdominal inflammation using other radioisotope techniques.

99mTc-HMPAO-labelled white cell scanning is compared with other radionuclide techniques in this contribution. The sensitivity and specificity using both 111In and 99mTc-HMPAO-labelled leucocytes are comparably high. Both imaging methods are therefore suitable for imaging inflammation. However, images are available more quickly using 99mTc-HMPAO; their quality is superior and the radiation dose is lower. 111In is beneficial for chronic infections. 67Ga citrate is less specific for inflammation, since it also localizes in tumours, but it is useful in chronic infection. 99mTc nanocolloid has not been found suitable for imaging abdominal inflammation, but more so for bone and joint diseases. Comparisons of 99mTc-HMPAO leucocytes with 123I-labelled monoclonal antibodies show poorer results using the monoclonal antibody because of non-specific binding to plasma proteins. Visualization of lesions is generally poorer using 99mTC-HIG than 99mTc-HMPAO leucocytes and is less sensitive and specific. Few reports using 99mTc-labelled monoclonal antibodies are available. Early results are promising and more specific antibodies may be available in the future. Synthetic chemotactic peptides offer a novel approach to the detection of infection. However, at present the recommended method for imaging acute abdominal inflammation is 99mTc-HMPAO leucocytes.

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.

Postoperative graft incorporation after aortic reconstruction--comparison between computerised tomography and Tc-99m-HMPAO labelled leucocyte imaging.

Aortic graft infection may result in high mortality ranging up to 88%. Therefore, early diagnosis is imperative in the treatment of this serious complication. Computerised tomography (CT) is considered as a sensitive tool in the diagnosis of aortic graft infection. Some findings used as the criteria for infection, such as periprosthetic gas and fluid are, however, normal postoperative findings. The aim of this prospective study was to compare CT-scan and Tc-99m-HMPAO labelled leucocytes in the early diagnosis of aortic graft infection. The present study includes 24 consecutive patients (all men, age 70 +/- 8 years, range 55-85 years), who were operated on for abdominal aortic aneurysm. Prosthetic and suture materials were the same in all operations. Each patient was examined with the aid of CT-scan and imaged with Tc-99m-HMPAO labelled leucocytes 2 weeks and 3, 6 and 12 months after the reconstructive aortic surgery. Two radiologists and two specialists in nuclear medicine examined the data independently without knowing the clinical picture of the results of any other examinations of the patients. Seven patients (7/24; 29%) showed significant accumulation of labelled leucocytes in the first imaging (2 weeks postoperatively) with Tc-99m-HMPAO labelled leucocytes. Three months after the surgery only four patients (4/24; 17%) were positive in this respect. One of these patients had clinically proven aortic graft infection and another positive was a patient with resected and reconstructed mycotic aneurysm. CT-examination in all scans was suggestive for aortic graft infection in two cases (2/24; 8%), but neither of these patients showed any signs of infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombus imaging with 99mTc-HMPAO-labeled platelets and 111In-labeled monoclonal antifibrin antibodies.

Eighteen patients with suspicion of deep venous thrombosis (DVT) in the lower extremities were imaged both with autologous 99mTc-HMPAO-labeled platelets (Tc-PLT) and 111In-labeled monoclonal antifibrin antibodies (In-MoAbs) on the same day. Presence or absence of thrombosis was verified by venography. Tc-PLT was given i.v. followed after 30 min by In-MoAbs. Anterior and posterior projections of the lower extremities were obtained with a large field-of-view gamma camera at 5 to 25 min, 2 h, 4 to 6 h, and 20 h after administration of the marker. Both Tc-PLT and In-MoAbs detected DVT well but less frequently than venography. Thrombi were visualized at 2 to 4 h after injection. The quality of images was better with Tc-PLT than with In-MoAbs. In the patients treated during the study, heparin significantly (p < 0.01) inhibited the uptake of Tc-PLT but not of In-MoAbs. We conclude that both Tc-PLT and In-MoAbs are suitable agents for the detection of DVT especially in patients without anticoagulation.

Venous thrombosis: a controlled study on the performance of scintigraphy with 99Tcm-HMPAO-labelled platelets versus venography.

Thirty-three patients with symptoms and signs of a deep venous thrombosis (DVT) were examined by contrast venography and radionuclide imaging with 99Tcm-hexamethylpropyleneamineoxime (99Tcm-HMPAO)-labelled autologous platelets. There were 13 patients on heparin therapy and 20 without anticoagulation during the scintigraphy. Scintigraphy consisted of blood pool imaging at 5 to 20 min and accumulation imaging at 2, 4-6 and 18-24 h. In scintigraphy a positive finding was either a defect of radioactivity in the immediate blood pool phase or a hot spot indicative of accumulation of platelets in later phases. Fifteen out of 23 patients positive by venography were also positive by scintigraphy. Five of the eight false negative patients were on heparin treatment, two probably had DVT which were not quite fresh. The venography negative patients were also negative on scintigraphy. Nine out of 12 patients without anticoagulation had positive platelet accumulation compared with two out of 11 patients on heparin therapy. This difference was statistically significant (P less than 0.025). The sensitivity and specificity of platelet scintigraphy were 65 and 100%, respectively, in all patients and 83 and 100% in patients without anticoagulation. Our results suggest that scintigraphy with 99Tcm-HMPAO-labelled platelets is a useful alternative in diagnosing DVT in patients in whom a standard contrast X-ray venograph is contraindicated or otherwise unsuccessful.

Technetium-99m hexamethyl propylene amine oxine leucocytes in the assessment of disease activity in inflammatory bowel disease.

The inflammatory activity in 108 bowel segments of 40 patients with suspected or known inflammatory bowel disease was assessed macroscopically by endoscopy, histology and technetium-99m hexamethyl propylene amine oxine (99mTc-HMPAO) leucocytes using a numerical grading system (scores 0-3). A 4-h series of scintigrams showed a significant correlation with both histological and macroscopical assessment of disease activity (rho = 0.850, P less than 0.001 and rho = 0.773, P less than 0.001, respectively). Sensitivity, specificity and accuracy of scintigraphy in detecting active inflammatory segments were 85%, 92% and 89%, respectively. A normal scintigram did not completely exclude mild inflammatory activity, especially in the rectosigmoid area. 99mTc-HMPAO leucocytes offer an accurate and non-invasive alternative for the assessment of disease activity in ulcerative colitis and Crohn's disease.

Tc-99m HMPAO labeled leukocytes superior to bone scan in the detection of osteomyelitis in children.

Seven children (aged 7 to 16 years) with confirmed osteomyelitis underwent imaging with Tc-99m HMPAO labeled leukocytes and with Tc-99m diphosphonates. The patients were scanned at 1/2 hour and at 3 hours. The scans were evaluated visually, and the lesion-to-normal bone ratios were quantitated. All the lesions on leukocyte scans and six out of seven lesions in bone scans were readily detectable 1/2 hour after injection of the radiopharmaceutical, but 3 hours is the better imaging time. In quantitative analysis, the lesion-to-normal bone ratio increased with leukocytes significantly higher than with the bone scans (P less than 0.05). When the scintigraphic findings were compared with surgical and radiologic results, the leukocyte images detected and localized lesions better than the bone scans. According to these preliminary results, Tc-99m HMPAO labeled leukocytes seem to offer a rapid and accurate method for detecting bone infections.

Simple procedure for red blood cell labeling with Tc-99m HMPAO. Preliminary clinical results.

Clinical applications for Tc-99m HMPAO labeled red blood cells have not been previously reported. The authors describe a simple, aseptic, closed, one-step centrifugal procedure for red blood cell labeling with Tc-99m HMPAO and isolation from whole blood, and they report the preliminary results of using these labeled red blood cells to detect acute gastrointestinal bleeding in 11 patients. Whole blood was radiolabeled with Tc-99m HMPAO preparation and blood cells were separated by centrifugation (30 min, 200 g, 20 degrees C) using Polyprep density gradient medium. Red blood cells contained about 50% of the radioactivity. Four out of the 11 patients imaged with a gamma camera after reinjection of labeled autologous red blood cells showed abnormal accumulation, suggesting gastrointestinal bleeding that was verified at surgery and was at the site of abnormal activity in all cases. Image quality with Tc-99m HMPAO was comparable to that of Tc-99m pertechnetate labeled pretinned red blood cells. Tc-99m HMPAO can be used as a red blood cell labeler; however, its elution rate from red blood cells limits its applicability in some investigations.

Fast diagnosis of abdominal infections and inflammations with technetium-99m-HMPAO labeled leukocytes.

The diagnostic value of early 99mTc-HMPAO-leukocyte images (2 min, 0.5 hr, 2 hr and 4 hr) was studied in 87 prospectively performed investigations in 80 patients with a suspicion of abdominal inflammation or infection. Sensitivity, specificity and accuracy were 74%, 85% and 77% in the 2-min scans, 88%, 81% and 86% in the 0.5-hr scans, 95%, 85% and 92% in the 2-hr scans, and 96%, 92% and 95% in the 4-hr scans. Nonspecific bowel accumulation was seen in 7% of patients at 2 hr and in 28% at 4 hr but was easily distinguishable from pathologic activity. The uptake in early images represents an active accumulation of granulocytes at the site of inflammation rather than nonspecific blood-pool activity judged by results of 99mTc-HMPAO-RBC imaging. We found that imaging within 2 hr from injection has a high diagnostic value, and that the activity accumulates in areas of infection and inflammation faster than in the intestinal background.

Scintigraphy with 99mTc-HMPAO labeled leukocytes in acute cholecystitis.

99mTc-HMPAO labeled leukocyte scanning was performed on 38 patients with clinically suspected acute cholecystitis (AC) to evaluate its diagnostic value. The typical finding was an increasing accumulation of the tracer in the gallbladder wall in a 4 hour series of scintigrams. Leukocyte scan was positive in 16 of 17 patients with surgically and histologically confirmed AC. There were no false-positive findings. The sensitivity, specificity, and accuracy of scintigraphy were 94, 100, and 96%, respectively. In 2 patients with acute acalculous cholecystitis true-positive findings were observed. Scintigraphy with 99mTc-HMPAO labeled leukocytes is a valuable new imaging method in AC.

Chronic prosthetic vascular graft infection visualized with technetium-99m-hexamethylpropyleneamine oxime-labeled leukocytes.

Technetium-99m-HMPAO labeled leukocytes demonstrated chronic femoro-femoral prosthetic vascular graft infection several times during an 18-mo period in a 77-yr-old man. The intensity and distribution of the uptake in the graft were fluctuating in different imaging occasions possibly indicating the strength and location of the infection. Gallium-67-citrate imaging showed negative results twice. The reason for negative 67Ga results remained obscure. The infected graft was removed and the patient did well 5 mo postoperatively.

Accumulation of leucocytes labelled with technetium-99m hexamethylpropylene amine oxime in malignant abdominal tumours.

A total of 343 leucocyte scans labelled with technetium-99m hexamethylpropylene amine oxime were reviewed that had been performed in 338 patients suspected of having abdominal infection or inflammation. There was uptake by malignant abdominal tumours in 10 cases (2.9%), which represents 62.5% of known malignancies at the time of the scintigram. Accumulation was seen in 8 patients with adenocarcinoma of the colon associated with a secondary infection in the tumour or pericolic inflammation. A large tumour that had spread beyond the bowel wall was related to a positive scintigram. Accumulation was also found twice in a malignant fibrous histiocytoma in which bleeding and an inflammatory reaction to necrosis were probably responsible for the uptake. The relevant treatment was delayed for 2 weeks-2 months in 4 patients with adenocarcinoma of the colon in whom the positive uptake was regarded as confirmation of the clinically suspected acute diverticulitis.

[99Tcm]MAG3 gamma camera nephrography in epidemic nephritis.

There is a lack of systematic nephrographic studies on epidemic nephritis (EN). We studied 10 patients with EN using [99Tcm]MAG3 gamma camera nephrography and followed up 9 of them 22-68 days later when they had clinically recovered. Variables for renal clearance of [99Tcm]MAG3 and the retention of radioactivity in the kidneys and blood were calculated. In all patients renal function was impaired acutely. There was marked reconstitution of renal function in the control studies. [99Tcm]MAG3 clearance was inversely related to serum creatinine. On visual inspection the nephrograms showed no focal changes. Nephrography was more sensitive than sonography at identifying renal impairment. [99Tcm]MAG3 nephrography is a sensitive method for identifying renal involvement and reconstitution of renal function in EN. It may be a valuable adjunct to the diagnostic arsenal, especially in nonendemic areas where EN occurs only sporadically and where there may be diagnostic uncertainty in patients presenting acutely with EN.

Septic Haemophilus influenzae polyarthritis demonstrated best with Tc-99m HMPAO labeled leukocytes.

A 5-year-old girl with fever and tenderness in her left wrist and right ankle was hospitalized. Bone scanning and Tc-99m labeled leukocyte imaging showed increased uptake in these joints and also in her left knee. These radionuclide methods helped determine the diagnosis and were superior to plain radiography and CT scanning. Uptake was greater on leukocyte imaging than it was on the bone scan. The patient had infectious polyarthritis caused by Haemophilus influenzae, which is a very rare cause of acute polyarthritis in children older than 2 years. The patient fully recovered with antibiotic therapy, and no surgical procedure was needed.

Tc-99m labeled leukocytes in imaging of patients with suspected acute abdominal inflammation.

One hundred patients with suspected acute abdominal inflammation were imaged at 0.5, 2-3, 4-6, and 24 hours after the administration of Tc-99m HMPAO labeled autologous leukocytes. Scan findings were retrospectively compared with final diagnosis, serum C-reactive protein (CRP), and antibiotic treatment. Clinical findings were confirmed with surgery, barium enema, or sigmoidoscopy in 61 patients, and diagnosis was based only on clinical findings in 13 patients. In 26 patients, symptoms subsided before a final diagnosis was made. Tc-99m leukocyte images were positive in 45 of the 61 patients with a confirmed diagnosis, including all patients with acute cholecystitis (N = 4) and inflammatory bowel disease (N = 8). They were also positive in nineteen out of 25 patients who had acute colonic diverticulitis and in 6 out of 7 who had intra-abdominal abscesses. Abnormal activity was found in patients with colonic carcinoma, small bowel infarction, and acute appendicitis. Abnormal activity was visualized in 0.5-hour images in all but one of the positive cases. With the exception of two postoperative cases, malignant lymphoma, and a liver abscess, a CRP level of greater than 75 mg/L was associated with positive image findings. Antibiotic treatment did not affect imaging findings. Imaging with Tc-99m labeled leukocytes appears to be valuable for detecting and localizing abdominal inflammation, and three-phase imaging during the first 4-6 hours is recommended. In some cases, 24-hour images may be useful for distinguishing small bowel from large bowel inflammation.

99mTc-HMPAO labelled leucocyte imaging in bowel infarction. Case report.

Two cases of small-bowel infarction preoperatively diagnosed with 99mTc-HMPAO labelled leucocyte imaging are reported. Uptake in the affected gut was positive in images recorded after only 30 min, which is helpful for early diagnosis and therapeutic strategy.