Labeled Leukocyte Scintigraphy Research Articles

Segmental Hepatic Concentration of 18F-FDG-Labeled Autologous Leukocytes Causing a “Pseudo-Lesion” on PET/CT in a Patient With Transient Hepatic Attenuation Difference

Labeled leukocyte scintigraphy has been described in the detection of infection in peripancreatic fluid collections in patients with acute pancreatitis. The authors describe a sectorial hepatic concentration of 18F-FDG-labeled autologous leukocytes forming a "pseudo-lesion" on PET/CT, matching the characteristic finding of transient hepatic attenuation difference on venous phase contrast-enhanced computerized tomography.

Técnicas de imagen en infección musculoesquelética

Imaging techniques are routinely used to evaluate patients with suspected musculoskeletal infection. Although radiographs will not establish the diagnosis, they should always be performed when infection is suspected because of their utility in differential diagnosis and follow-up. Radiographs provide an overview of the anatomical region of interest and of previous alterations that can influence the selection and interpretation of subsequently used techniques. Magnetic resonance imaging is the most sensitive examination, does not irradiate, and provides excellent anatomic detail and rapid results. This technique is especially valuable in spondylodiscitis, osteomyelitis, and diabetic foot infections. Its main limitations are the false-positives caused by nonspecific bone edema and poor reliability in the assessment of short-term therapeutic response. Among nuclear medicine procedures, the 3-phase bone scan is widely available and highly accurate in previously healthy bone. Labeled leukocyte scintigraphy should be used in complicated osteomyelitis, such as prosthetic infection, although it is also useful to exclude infection in diabetic foot and neuropathic joints. Ga-67 scintigraphy is useful in spinal infections. In these infections, positron emission tomography can also be a useful alternative. Finally, it is important to remember atypical radiological presentations in distinct locations and particular clinical situations, as well as certain conditions that can mimic infection.

Incidental Detection of Colonic Inflammation on PET/CT Using 18F-FDG–Labeled Autologous Leukocytes

Labeled leukocyte scintigraphy and (18)F-FDG PET are well-documented techniques for the assessment of inflammatory bowel disease. In this study, a 28-year-old man with abdominal pain, vomiting, and raised serum amylase and lipase levels underwent PET/CT imaging using FDG-labeled autologous leukocytes to assess for pancreatic infection. While the pancreas showed no abnormal tracer uptake, colonic inflammation was incidentally detected, and a diagnosis of pseudomembranous colitis was subsequently confirmed on colonoscopy and biopsy.

The use of radioisotopic tests for diagnosing lower limb venous thrombosis - own research.

Inflammatory mediators play an important role in thrombosis etiopathology. Diagnostic radioisotopic tests can be used to assess the activity of thrombo-inflammatory process. The aim of the study was to assess the suitability of Tc-99m HMPAO labelled leukocyte scintigraphy in the diagnostics of deep vein thrombosis. The study covered 45 patients with lower limb deep vein thrombosis treated in 2009 at the Department of Vascular, General and Transplantological Surgery of the Wrocław Medical University. Scintigraphic test were performed during the first few days after the onset of symptoms and 8 weeks later. All patients with active deep vein thrombosis had higher levels of TC-99m-HMPAO markers in sick limbs. After 8 weeks, 93% of patients still had elevated levels of radioisotope in limbs with an active thrombosis process. However, the levels of markers were clearly lower than in the acute phase of thrombosis. 1. In the chronic phase of thrombosis, 93% of patients still have higher levels of radioisotopic markers, which indicates an active inflammatory process. 2. Tc-99m HMPAO labelled leukocyte scintigraphy demonstrates high sensitivity in the diagnostics of deep vein thrombosis.

Infection of Pancreatic Pseudocyst Demonstrated on PET/CT Using 18F-Fluorodeoxyglucose–Labeled Autologous Leucocytes

Labeled leukocyte scintigraphy has been used as an indicator of pancreatic necrosis in patients with acute pancreatitis and proposed for the detection of infection in peripancreatic fluid collections. The authors present a PET/CT scan showing abnormal uptake of 18F-Fluorodeoxyglucose-labeled autologous leukocytes in a pancreatic pseudocyst, from which aspirated fluid subsequently showed growth of Pseudomonas aeruginosa.

An incidental detection of popliteal vein aneurysm during labeled leukocyte scintigraphy

Technetium (99mTc) exametazime (hexamethylpropyleneamine oxime, HMPAO) labeled leukocyte scintigraphy is mainly used to exclude occult infection in our institution. On review of previously published article, no case of popliteal venous aneurysm was ever diagnosed and detected on labeled leukocyte scintigraphy. We present a rare case of popliteal venous aneurysm which was detected on labeled leukocyte scintigraphy and was further confirmed with single-photon emission computed tomography and computed tomography fusion.

Diagnosis of bone infection by complementary role of technetium-99m MDP and technetium-99m hexamethylpropylene-amineoxime-leukocytes

Purpose:Valuate complementary role of 99mTc-MDP bone scan and 99mTechnetium hexamethylpropylene-amineoxime (99mTc-HMPAO) labeled leukocyte scintigraphy in diagnosis of bone infection.Patients and Methods:Ninety one sites suspected to have bone infection were divided in to two groups: Group I 49 sites with current endo-prothesis; and group II 42 sites with no prosthesis. All patients were subjected to serial images of 99mTc-HMPAO labeled leukocyte (99mTc-white blood cells (WBCs)), triple phase bone scan (99mTc-MDP) and plain X-ray, in addition to clinical and bacteriological assessment, together with follow-up.Results:The overall sensitivity (Sn) was found to be 34.9%, 95.4%, and 86% for plain X-ray, 99mTc-MDP, and 99mTc-WBCs respectively. Concerning specificity (Sp) was found to be 47.9%, 45.8%, and 91.7% respectively for the three imaging modalities. 99mTc-WBCs showed better Sn, Sp, and accuracy in group I (95%, 93.1% and 93.9%, respectively) compared to 40%, 41.4%, and 40.8% for plain X-ray and 90%, 62%, and 73.5% respectively for 99mTc-MDP. On the other hand, 99mTc-MDP proved to have best Sn 100% versus 78.3% and 30.4% for 99mTc-WBCs and plain X-ray respectively. Yet, Sp and accuracy was found to best for 99mTc-WBCs (89.5% and 83.3% respectively) compared to 57.9% and 42.9% for plain X-ray and 21.1% and 64.3% for 99mTc-MDP.Conclusion:Combined imaging with 99mTc-WBCs and 99mTc-MDP proved to be effective in early detection of bone infection in the presence or absence of prosthesis.

99mTc-HMPAO labelled white blood cell scintigraphy in the diagnosis and monitoring of response of the therapy in patients with active bronchiectasis

AimThe aim of this study was to assess the role of labelled leukocyte scintigraphy in the diagnosis and monitorization of response to therapy of patients with active bronchiectasis. Material and methodsTwenty patients underwent 99mTechnetium hexamethylpropyleneamine oxime (99mTc-HMPAO) labelled white blood cell (WBC) scintigraphy. A second scintigraphy was performed in 13 patients at 10 day of the treatment. Regional 99mTc-HMPAO WBC uptake and radiologic imaging findings (high resolution computed tomography or Chest X-Ray) in the lungs were classified into 3 categories in 6 lung areas. scintigraphic, radiological and clinical disease scores were calculated for all patients. ResultsAn abnormal accumulation was visually observed in 19 of 20 patients on the pre-treatment scans, the scintigraphy showing 95% sensitivity. A significant difference was found between early and late ratios (P=0.001) in the pre-treatment scans. The infected areas revealed a significant decrease in uptake ratios on the post-treatment scans compared to the pre-treatment scans (P=0.001). However, no significant correlation was determined between clinical and radiological scores, clinical and scintigraphic scores and also between scintigraphic and radiological scores (P≥0.05). Conclusions99mTc-HMPAO WBC scintigraphy may be a useful tool to evaluate response to therapy in patients with active bronchiectasis.

99mTc-HMPAO labelled white blood cell scintigraphy in the diagnosis and monitoring of response of the therapy in patients with active bronchiectasis

AimThe aim of this study was to assess the role of labelled leukocyte scintigraphy in the diagnosis and monitorization of response to therapy of patients with active bronchiectasis. Material and methodsTwenty patients underwent 99mTechnetium hexamethylpropyleneamine oxime (99mTc-HMPAO) labelled white blood cell (WBC) scintigraphy. A second scintigraphy was performed in 13 patients at 10 day of the treatment. Regional 99mTc-HMPAO WBC uptake and radiologic imaging findings (high resolution computed tomography or Chest X-Ray) in the lungs were classified into 3 categories in 6 lung areas. scintigraphic, radiological and clinical disease scores were calculated for all patients. ResultsAn abnormal accumulation was visually observed in 19 of 20 patients on the pre-treatment scans, the scintigraphy showing 95% sensitivity. A significant difference was found between early and late ratios (P=0.001) in the pre-treatment scans. The infected areas revealed a significant decrease in uptake ratios on the post-treatment scans compared to the pre-treatment scans (P=0.001). However, no significant correlation was determined between clinical and radiological scores, clinical and scintigraphic scores and also between scintigraphic and radiological scores (P≥0.05). Conclusions99mTc-HMPAO WBC scintigraphy may be a useful tool to evaluate response to therapy in patients with active bronchiectasis.

Prosthesis-Related Abscess on In-111 Leukocyte SPECT/CT Imaging.

A 77-year-old male with a history of right knee joint replacement 4 years ago presented with swelling and pain following a fall. He soon developed fever with an elevated WBC count, ESR and CRP levels. Blood cultures were negative. Whole body images were acquired in anterior and posterior projections after the intravenous administration of 543 μCi of In-111-labeled autologous WBCs (a,b). They showed a large area of abnormal accumulation of labeled WBCs in the right thigh. CT and fused SPECT/CT images in the coronal plane (c,d) localized the uptake to the antero-lateral aspect of the right femoral prosthesis, extending into the knee. Transaxial CT and fused SPECT/CT images (e,f) localized the uptake to an abnormal density with an air-fluid level (e) characteristic of an abscess (Fig. 1). The patient underwent drainage, irrigation and debridement. Fig. 1 Whole body images were acquired in anterior and posterior projections after the intravenous administration of 543 μCi of In-111-labeled autologous WBCs (a, b). They show a large area of abnormal accumulation of labeled WBCs in the right ... In-111-Labeled leukocyte scintigraphy is the imaging modality of choice for evaluation of patients with suspected joint replacement infections [1]. As compared to CT and MRI, scintigraphy is not limited by orthopedic hardware, and in combination with bone marrow scans (using Tc-99 m sulfur colloid), provides excellent sensitivity and specificity for the diagnosis of prosthesis infection [2, 3]. Limitations of In-111 labeled leukocyte scintigraphy include low image quality and poor anatomical resolution [4]. Fusion of SPECT images with a separately acquired CT has been shown to facilitate interpretation and alter patient management [5, 6]. SPECT/CT is gaining popularity as a hybrid imaging modality where the functional (scintigraphic) and anatomic (low dose CT) information is acquired together to generate coregistered images. SPECT/CT imaging has been shown to improve the sensitivity and specificity of labeled leukocyte imaging by providing the precise localization and extent of abnormalities [7, 8]. This case highlights the importance of SPECT/CT hybrid imaging in In-111 leukocyte scintigraphy.

Infection de prothèse vasculaire : 18TEP-FDG vs scintigraphie aux leucocytes marqués (planaires et TEMP/TDM)

Vascular prosthesis infection is an uncommon but life-threatening complication. Its diagnosis is difficult to establish especially due to the low specificity of computed tomography (CT). The aim of this preliminary study was to compare the diagnostic value of positron emission tomography with 18FDG ( 18FDG-PET) and 99mTc-HMPAO-labeled leukocytes scintigraphy in this indication. 18FDG-PET/CT and 99mTc-HMPAO-labeled leukocytes scintigraphy (planar at 6th and 24th hours after injection + SPECT/CT at the 6th hour) were prospectively performed in 11 patients (total of 22 vascular prosthesis with 14 clinical suspicions of infection). Both scans were retrospectively and blindly assessed by two independent nuclear medicine physicians. Interpretation was based on visual analysis. The gold standard was bacteriology findings or clinical follow-up greater than 6 months. Eight prostheses were considered as infected. PET found eight true-positive and one false-positive. Scintigraphy found eight true-positive and no false-positive. A focal or heterogeneous FDG-uptake higher or equal than hepatic uptake was considered as positive in PET. A focal prosthetic activity, stable or increased at the 24th hour was considered as positive in labeled leukocyte scintigraphy. SPECT/CT gave accurate anatomic localization and differentiated clearly infections of soft tissues from those of prostheses. 18FDG-PET could be performed in first-line in suspicion of vascular prosthesis infection. In litigious cases, a 99mTc-HMPAO-labeled leukocytes scintigraphy in association with SPECT/CT could bring additional arguments for infection diagnosis.

Benefits of Hybrid SPECT/CT for 111In-Oxine- and Tc-99m-Hexamethylpropylene Amine Oxime-Labeled Leukocyte Imaging

This retrospective study assessed the effect of the addition of SPECT/CT imaging on the diagnostic accuracy of labeled leukocyte scintigraphy. Leukocyte scans of 134 patients performed between December 2005 and December 2009 were reviewed. All patients underwent whole-body planar and SPECT/CT imaging with either (111)In-oxine- or Tc-99m-hexamethylpropylene amine oxime (HMPAO)-labeled leukocytes. Leukocyte imaging identified a total of 221 lesions. Based on additional diagnostic tests and clinical follow-up, a final diagnosis was established in 115 patients. A total of 113 focal lesions with an established final diagnosis were detected on imaging in bone (n = 43), soft-tissues (n = 34), vascular grafts (n = 19), and other surgical implants (n = 17), whereas 26 scans resulted negative. Overall, leukocyte scanning including SPECT/CT yielded sensitivity, specificity, positive and negative predictive values of 87.5%, 85.3%, 83.6%, and 88.9%, respectively. As compared to planar imaging and SPECT, SPECT/CT imaging significantly increased the number of correctly identified lesion locations and improved overall reader confidence in 77 (68%) and 71 (63%) of 113 focal lesions, respectively (P < 0.001). Significant differences in scan accuracy were neither observed between In-oxine- or Tc-99m-hexamethylpropylene amine oxime-labeled leukocyte studies, nor between scans obtained with or without antibiotic treatment. Hybrid SPECT/CT leukocyte imaging has incremental value over planar imaging with SPECT because of improved diagnostic accuracy of lesion identification and reader confidence.

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.

Tc-99m Exametazime (HMPAO)-Labeled Leukocyte Scintigraphy in Premature Infants

Two cases of successful detection of inflammatory foci using Tc-99m exametazime (HMPAO)-labeled leukocyte scintigraphy in premature infants were reported. Necrotizing enterocolitis was detected in a child with a body weight of 1.6 kg. Scintigraphy confirmed a neonatal osteomyelitis in the distal part of the leg of another patient weighing 2.2 kg. These 2 cases indicate that it is feasible to perform Tc-99m HMPAO-labeled leukocyte scintigraphy even if the blood sample volume is lower than the minimal volumes required by the guidelines for pediatric patients.

Inflammatory bowel disease: value in diagnosis and management of MDCT-enteroclysis and 99mTc-HMPAO labeled leukocyte scintigraphy

The aims of this study are: (a) to evaluate the reliability of Multidetector Computed Tomography Enteroclysis (MDCT-E) and (99m)Tc-HMPAO labeled leukocyte scintigraphy (TLLS), in inflammatory bowel disease, (b) to test the accuracy of the two techniques with regard to their histological results, (c) to define how each technique can influence the natural course of inflammatory bowel disease (IBD), (d) to assess the potential value of the two techniques combined. Thirty-seven patients with suspected IBD underwent MDCT-E and TLLS. We made a separate assessment of the results shown by the two methods and then compared and contrasted the histological results of the two. The latter, however, were either disappointing or not available in 15 patients who, for this reason, had to be dismissed from the study. As result, the number of participants eventually dropped to 22 subjects: 12 women, 10 men with an average age of 44 years. MDCT-E and TLLS were successful in all patients. Sensitivity, specificity, and efficiency values have been reported as follows: MDCT-E: 62%, 100%, 64%,100%, 11%, respectively. TLLS: 90%, 100%, 91%, 100%, 33%, respectively. The two methods combined: 95%, 100%, 95%, 100%, 50%, respectively. The two techniques can be employed in different stages of the natural course of the disease. In our experience, TLLS proved itself to be useful in the diagnosis of the disease and the assessment of its development. Conversely, MDCT-E proved itself to be more reliable in identifying the seat and the extent of the disease inside and outside the bowel wall as well as potential intra-peritoneal and extra-intestinal complications. The combined use of the two methods represents the Criterion Standard for diagnosing IBD with imaging.

Gram-positive occult bacteremia in patients with pacemaker and mechanical valve prosthesis: a difficult therapeutic challenge

In pacemaker patients with Gram-positive occult bacteremia, it is reasonable to remove the whole stimulation system, but therapeutic decision is sometimes very challenging. A young patient at 6 years of age underwent dual-chamber pacemaker implantation due to complete atrioventricular block after mitral valve replacement. He felt well until November 2008, when he suffered from febrile illness with blood cultures disclosing methicillin-resistant staphylococcus aureus strain. Repeated antibiotic courses were effective only in obtaining temporary remissions. Consecutive transoesophageal echocardiography examinations were inconclusive. A labelled leucocyte scintigraphy, showing increased captation along leads, was very helpful and critical in guiding our decision to extract leads. In equivocal cases, or when the hazard of extraction procedure is presumably high, every accessory diagnostic tool (like scintigraphy with labelled leucocytes) is helpful in establishing a definitive diagnosis and in strengthening a somewhat difficult decision.

Non-invasive diagnosis and grading of postsurgical endoscopic recurrence in Crohn's disease: Usefulness of abdominal ultrasonography and 99mTc-hexamethylpropylene amineoxime-labelled leucocyte scintigraphy

Non-invasive techniques aim to be an alternative to endoscopy in the assessment of postsurgical recurrence of Crohn's disease (CD). The object of this study was to evaluate the accuracy of abdominal ultrasonography (AUS) and 99mTc-hexamethylpropylene amineoxime (99mTc-HMPAO)-labelled leucocyte scintigraphy (LLS) compared with endoscopy in the diagnosis and grading of postsurgical recurrence of CD.Between January 2006 and May 2007, all patients with CD and resection with ileocolic anastomosis were included prospectively. Within three days they underwent an ileocolonoscopy, AUS with evaluation of bowel wall thickness and the presence of Doppler flow, and LLS.Forty patients who met the study conditions were included; 5 patients did not agree to have the ileocolonoscopy and it was not possible to assess the anastomosis in 2 patients. Endoscopic recurrence was detected in 26 patients (78.8%), in 15 of whom it was moderate-severe. For the diagnosis of recurrence, both AUS and LLS showed acceptable sensitivity and positive predictive value, with an accuracy of 72.7% and 78.1%, respectively. The results of the AUS and LLS for diagnosing moderate-severe recurrence were better, with an accuracy of 78.8% and 81.3%, respectively. The best assessment of the severity of the recurrence was obtained with the combination of both techniques (sensitivity, specificity, positive and negative predictive values, accuracy and kappa index were, respectively: 93.3%, 72.2%, 73.7%, 92.9%, 81.8% and 0.64). The variables evaluated, both sonographic and scintigraphic, had areas under the curve that were similar and significantly different from 0.5.Conclusion: Abdominal ultrasonography and 99mTc-HMPAO-labelled leucocyte scintigraphy are two useful non-invasive techniques for the assessment of postsurgical recurrence of Crohn's disease.

Comparison of detection of F-18 fluorodeoxyglucose positron emission tomography and 99mTc-hexamethylpropylene amine oxime labelled leukocyte scintigraphy for an aortic graft infection☆

To compare F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG-PET) and (99m)Tc-hexamethylpropylene amine oxime ((99m)TC-HMPAO) labelled leukocyte scintigraphy for the diagnosis of vascular graft infection. A thoraco-abdominal CT-angiography and a (99m)TC-HMPAO labelled leukocyte scintigraphy did not show any graft infection in this case report whereas an F-18 FDG-PET showed a metabolic uptake around and all along the vascular graft. Further comparison between these two explorations is needed since the two techniques have not been compared in vascular graft infection.

Technetium-99m hexamethyl propylene amine oxime-labeled leukocyte scintigraphy at three different times in active ulcerative colitis: comparison with colonoscopy and clinico-biochemical parameters in the assessment of disease extension and severity

In this study, our objective was to define the usefulness of technetium-99m hexamethyl propylene amine oxime (Tc-99m HMPAO)-labeled leukocyte scintigraphy at three different time points in the assessment of disease extension and severity in patients with active ulcerative colitis (UC). Twenty-one consecutive patients (10 women, 11 men; mean age 42.4 +/- 12 years) with active UC were prospectively studied. All patients were diagnosed by colonoscopy and histopathology prior to inclusion. Scintigraphy was performed at 1 h, 2 h, and 4 h after Tc-99m HMPAO-labeled leukocyte injection. Clinic-biochemical activity score, total colonoscopic activity score, and total scintigraphic activity score at 1 h, 2 h, and 4 h were calculated for each patient. Sensitivity, specificity, and accuracy values of Tc-99m HMPAO-labeled leukocyte scintigraphy were calculated as follows, respectively: 1 h imaging 86%, 73%, and 83%; 2 h imaging 89%, 74%, and 86%; 4 h imaging 90%, 58%, and 83% in the detection of active inflammatory segments. Even though no statistically significant difference was found between 1 h, 2 h, and 4 h imaging with respect to the sensitivity, specificity of labeled leukocyte scintigraphy, the largest area under the curve value was found for 2 h imaging. Tc-99m HMPAO-labeled leukocyte scintigraphy has been found to be correlated well with colonoscopy in the assessment of both the extension and severity of UC. We recommend 2 h scintigraphic imaging because it provides the largest area under the curve value and decreases the number of false-positive results.

Usefulness of Technetium-99m Hexamethylpropylene Amine Oxime-Labeled Leukocyte Scintigraphy to Detect Pancreatic Necrosis in Patients with Acute Pancreatitis: Prospective Comparison with Ranson, Glasgow and APACHE-II Scores and Serum C-Reactive Protein

Background: In acute pancreatitis (AP), pancreatic necrosis (PN) is an important local complication that can be identified by means of contrast-enhanced computed tomography (CECT). Pancreatic leukocyte infiltration is a significant pathogenic event in the development of PN that can be detected by labeled leukocyte scintigraphy (LLS). The aim of this study was to evaluate the utility of LLS with technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) to detect the presence of PN in patients with AP. Methods: Prospective cohort study of 84 patients with AP. Patients underwent LLS and the activity of images was scored on a 0–3 scale. CETC was performed to assess PN. Ranson, Glasgow and APACHE-II scores were calculated. Serum C-reactive protein (CRP) was measured. Sensitivity (Sn), specificity (Sp), positive predictive values (PPV), negative predictive values (NPV), areas under receiver operating characteristic (ROC) curves, likelihood ratios, odds ratios, analysis of variances between groups and correlation coefficients between tests were calculated. Results: PN was present in 11 (13%) patients. Pancreatic labeled leukocyte uptake was present in 38 patients (45%). Sn, Sp, PPV and NPV of LLS grade 2–3 for PN diagnosis were the highest (91, 88, 53 and 98%, respectively) of all tests. Patients with LLS grade 2–3 were 71 times more likely to be at risk of PN compared to those with LLS grade 0-1. The area under ROC curve of the LLS was the largest. A significant correlation was obtained between LLS and CRP (p < 0.001). Conclusion: In patients with AP, LLS with 99mTc-HMPAO detects PN with an acceptable level of confidence and therefore could be considered an alternative technique to CECT in detecting PN.