Granulocyte radiolabeling using Leukokit® with introduction of a density gradient medium as ancillary material.

BACKGROUND: Radiolabeled white blood cells (WBCs) prepared in radiopharmacies are used to detect infectious or inflammatory sites with scintigraphy. Radiolabeling can be performed by using a disposable closed device, Leukokit®. Nevertheless, owing to the high radiosensitivity of lymphocytes, the question of eliminating lymphocytes before granulocyte radiolabeling is still a controversial step. The aim of this study was to assess a new modified Leukokit® with a protocol that allows granulocyte radiolabeling only. METHODS: Seventy patients (male/female: 40/30, mean age: 61 years) with suspected infectious diseases underwent labeled leukocyte scintigraphy by radiolabeling with a density gradient medium in addition to Leukokit®. Compliance and quality of radiolabeling were checked according to the following criteria: visual inspection, labeling efficiency, cell viability (Trypan blue exclusion test), cell subset recovery test, lymphocyte elimination rate (granulocyte/WBC rate) and sterility test using media fills. RESULTS: Visual inspection showed that all cell preparations were free of residual cell clumps or fibrin clots. Mean labeling efficiency was 70.4±9.4% compliant with EANM Guidelines for leukocyte labeling. The mean cell viability was 97.7±1.4% (>96%). The mean number of leucocytes injected was 116x106 ±62x106 (>50x106). The mean erythrocyte/WBC ratio was 2.1 ±0.9 (<3) and the removed lymphocyte rate was 97.4±1.6% (>90%). Finally, the three sterility tests were negative and therefore successful. CONCLUSIONS: Purification of granulocytes with Leukokit® can safely, easily and effectively be performed using a density gradient medium. Moreover, clarification regarding the status of density gradient medium could provide support for its clinical use even if further studies are needed. Since all technical obstacles have been removed, the precautionary principle should apply and lead users to eliminate lymphocytes that are highly radiosensitive cells and whose in vivo fate is uncertain.

False positive 18FDG PET-CT results due to exogenous lipoid pneumonia secondary to oily drug inhalation: A case report.

RATIONALE: Exogenous lipoid pneumonia is a rare condition due to abnormal presence of oily substances in the lungs. It is a rarely known cause for false positive FDG PET-CT results and can sometimes lead to invasive investigations. Searching and finding the source of the oily substance is one of the keys to the diagnosis. Inhalation of oily drugs during snorting has rarely been described. PATIENT CONCERNS: A patient with well controlled HIV infection was referred for an FDG PET-CT to assess extension of Kaposi's disease, recently removed from his right foot. The patient had no particular symptoms. DIAGNOSES: Abnormal uptake of FDG was found in a suspicious lung nodule. An experienced radiologist thought the nodule was due to lipoid pneumonia. INTERVENTIONS: Bronchoalveolar lavage fluid did not contain lipid-laden macrophages but bronchoscopy showed violet lesions resembling Kaposi's disease lesions. Lobectomy was performed after a multidisciplinary discussion. OUTCOMES: Anatomopathological analysis revealed the nodule was due to lipoid pneumonia. The patient's quality of life did not diminish after the operation and he is still in good health. The source of the oily substance causing lipoid pneumonia was found after the surgery: the patient used to snort oily drugs. LESSONS: The presence of a suspicious lung nodule possibly due to lipoid pneumonia in a patient with known Kaposi's disease was difficult to untangle and lead to invasive surgery. It is possible that if a source of exogenous lipoid pneumonia had been found beforehand, surgery could have been prevented.