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

Is 99mTc-HMPAO-leukocyte imaging an accurate method in evaluating therapy result in prosthetic joint infection and diagnosing suspected chronic prosthetic joint infection?

BACKGROUND

To investigate the sensitivity and specificity of 99mTc-HMPAO-leukocyte imaging in evaluating therapy result in patients with prosthetic joint infection (PJI) and in diagnosing suspected chronic PJI.

METHODS

Sixty-two patients (63 joints) with microbiologically verified PJI were examined by leukocyte imaging to evaluate therapy result during or at the end of antibiotic treatment or if the patient had a chronic PJI after treatment. Group 1 consisted of 49 patients with on-going or within less than 14 days of ending antibiotic treatment examined to evaluate response. Group 2 consisted of 13 patients examined after completed treatment on suspicion of chronic PJI with no or recently initiated renewed antibiotic treatment. This study applied a combination of different imaging approaches of 99mTc-HMPAO-leukocyte scintigraphy: delayed and late planar images, bone marrow imaging and SPECT/CT imaging. All joints were examined with at least two of the approaches and 53 joints with all three approaches. The report was based on the combined results of the approaches used. A chronic PJI was confirmed with a positive microbiological culture. A cured infection was confirmed with either a negative culture or at least 24 months antibiotic-free follow-up with no relapse.

RESULTS

In the therapy evaluation group sensitivity was 0.57 and specificity was 0.81. In the suspected chronic infection group sensitivity was 1.00 and specificity 0.91.

CONCLUSIONS

99mTc-HMPAO-leukocyte imaging appears to be an accurate method to diagnose or exclude chronic PJI, but cannot be recommended for therapy evaluation of PJI in patients with on-going antibiotic treatment.

Radionuclide Imaging of Infection and Inflammation in Children: a Review

With the exception of radiolabeled monoclonal antibodies, antibody fragments and radiolabeled peptides which have seen little application in the pediatric population, the nuclear medicine imaging procedures used in the evaluation of infection and inflammation are the same for both adults and children. These procedures include (1) either a two- or a three-phase bone scan using technetium-99m methylene diphosphonate; (2) Gallium 67-citrate; (3) in vitro radiolabeled white blood cell imaging (using ¹¹¹Indium-oxine or ^99mTechnetium hexamethyl-propylene-amine-oxime-labeled white blood cells); and (4) hybrid imaging with ¹⁸F-FDG. But children are not just small adults. Not only are the disease processes encountered in children different from those in adults, but there are developmental variants that can mimic, but should not be confused with, pathology. This article discusses some of the differences between adults and children with osteomyelitis, illustrates several of the common developmental variants that can mimic disease, and, finally, focuses on the increasing use of ¹⁸F-FDG PET/CT in the diagnosis and response monitoring of children with infectious and inflammatory processes. The value of and need for pediatric specific imaging protocols are reviewed.

Nuclear medicine imaging of infection in cancer patients (with emphasis on FDG-PET)

Infections are a common cause of death and an even more common cause of morbidity in cancer patients. Timely and adequate diagnosis of infection is very important. This article provides clinicians as well as nuclear medicine specialists with a concise summary of the most important and widely available nuclear medicine imaging techniques for infectious and inflammatory diseases in cancer patients with an emphasis on fluorodeoxyglucose positron emission tomography (FDG-PET). ⁶⁷Ga-citrate has many unfavorable characteristics, and the development of newer radiopharmaceuticals has resulted in the replacement of ⁶⁷Ga-citrate scintigraphy by scintigraphy with labeled leukocytes or FDG-PET for the majority of conditions. The sensitivity of labeled leukocyte scintigraphy in non-neutropenic cancer patients is comparable with that in patients without malignancy. The specificity, however, is lower because of the uptake of labeled leukocytes in many primary tumors and metastases, most probably as a result of their inflammatory component. In addition, labeled leukocyte scintigraphy cannot be used for febrile neutropenia because of the inability to harvest sufficient peripheral leukocytes for in vitro labeling. FDG-PET has several advantages over these conventional scintigraphic techniques. FDG-PET has shown its usefulness in diagnosing septic thrombophlebitis in cancer patients. It has also been shown that imaging of infectious processes using FDG-PET is possible in patients with severe neutropenia. Although larger prospective studies examining the value of FDG-PET in cancer patients suspected of infection, especially in those with febrile neutropenia, are needed, FDG-PET appears to be the most promising scintigraphic technique for the diagnosis of infection in this patient group.

Leukocyte scintigraphy compared to intraoperative small bowel enteroscopy and laparotomy findings in Crohn's disease

BACKGROUND

Leukocyte scintigraphy is a noninvasive investigation to assess inflammation. We evaluated the utility of labeled leukocytes to detect small bowel inflammation and disease complications in Crohn's disease and compared it to whole small bowel enteroscopy and laparotomy findings.

METHODS

Scintigraphy with technetium-99m exametazime-labeled leukocytes was prospectively performed in 48 patients with Crohn's disease a few days before laparotomy; 41 also had an intraoperative small bowel enteroscopy. The same procedures were performed in 8 control patients. Independent grading of scans was compared with the results of enteroscopy and with surgical, histopathologic, and clinical data.

RESULTS

In the 8 control patients leukocyte scan, endoscopy, and histopathology were all negative for the small bowel. In patients with Crohn's disease and small bowel inflammation seen at enteroscopy and/or laparotomy (n = 39) the scan was positive in 33. In 8 patients without macroscopic small bowel inflammation, the scan was positive for the small bowel in 3 patients; at histology, 2 of 3 had inflammation. When combining results for patients and controls, the sensitivity of leukocyte scan for macroscopically evident small bowel inflammation was 0.85, specificity 0.81, accuracy 0.84, positive predictive value 0.92, and negative predictive value 0.68. Scintigraphy detected inflammatory lesions not known before laparotomy in 16 of 47 (34%) Crohn's disease patients and showed uptake in 25 of 35 (71%) bowel strictures. It was diagnostic regarding 4 of 8 abscesses and 9 of 15 fistulas. In 6 patients (13%) lesions first demonstrated by leukocyte scintigraphy were treated during the surgery performed.

CONCLUSIONS

Leukocyte scintigraphy reliably detects small bowel inflammation in Crohn's disease. It gives additional information on the presence of inflammatory lesions in a fraction of patients planned for surgery.

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.

Investigation of suspected intra-abdominal sepsis: the contribution of nuclear medicine

The diagnosis of abdominal infections and inflammations often presents considerable difficulty, and various imaging techniques may be required to localize them accurately. At present, radiolabelled leucocytes offer the most widely accepted radionuclide method for imaging inflammation. Because of the many advantages of technetium-99m (99mTc) over indium-111 (111In), 99mTc-HMPAO-leucocyte scintigraphy is preferred for the investigation of acute abdominal sepsis and inflammatory bowel disease, and 111In-leucocyte scintigraphy for more chronic infections and renal sepsis. The 99mTc-HMPAO-labelled leucocytes technique is highly accurate within the first few hours postinjection, and is therefore useful also in acutely ill patients. It is sensitive in detecting abdominal abscesses in all locations except the liver and spleen. By whole body imaging, unsuspected sites and types of infection can be found. 99mTc-HMPAO-leucocyte scan is valuable also in the investigation of acute cholecystitis in problematic situations in which ultrasound is known to give misleading results, especially in acute acalculous cholecystitis. In inflammatory bowel disease it can reliably assess disease activity, but a normal scintigraphy does not exclude mild inflammation. Leucocyte scan is useful also in suspected acute appendicitis, acute diverticulitis, pelvic inflammatory disease, aortic graft infection, etc. But infection and inflammation cannot reliably be differentiated, which may cause misinterpretations in the early postoperative period. Radionuclide techniques have an important role to play in the investigation of abdominal sepsis if the nuclear medicine department can offer instant investigations when the clinical problem is acute.