F De Winter

Promising Role of 18-F-Fluoro-D-Deoxyglucose Positron Emission Tomography in Clinical Infectious Diseases

Abstract.18-F-fluoro-D-deoxyglucose positron emission tomography (FDG PET) has become an established imaging tool in clinical oncology, cardiology and neurology and is now entering the field of clinical infectious diseases. The purpose of this article is to review the currently available, albeit limited, literature on FDG PET in the diagnosis of various infections and fever of unknown origin. Those indications for which FDG PET offers added value over more available techniques like labelled leucocyte scanning, gallium scanning and magnetic resonance imaging are especially highlighted. FDG PET seems to have an incremental value in the assessment of chronic osteomyelitis, especially in the axial skeleton, as well as in the diagnostic workup of fever of unknown origin and HIV complications. Cost-effectiveness studies are needed to define its place in the current diagnostic strategies of these pathologies.

Fluorine-18 fluorodeoxyglucose-positron emission tomography: A highly accurate imaging modality for the diagnosis of chronic musculoskeletal infections.

Background: The noninvasive diagnosis of chronic musculoskeletal infections remains a challenge. Recent studies have indicated that fluorine-18 fluorodeoxyglucose-positron emission tomography is a highly accurate imaging technique and is significantly more accurate than the combination of a bone scan and a white blood-cell scan for the diagnosis of chronic infection in the central skeleton (p < 0.05). However, patients who had had surgery within the previous two years were excluded from study. It was our aim to evaluate the technique in an unselected, clinically representative population. Methods: Sixty patients with a suspected chronic musculoskeletal infection involving the central skeleton (thirty-three patients) or the peripheral skeleton (twenty-seven patients) were studied with fluorine-18 fluorodeoxyglucose-positron emission tomography. Thirty-five patients had had surgery within the previous two years. The fluorine-18 fluorodeoxyglucose-positron emission tomography studies were read in a blinded, independent manner by two experienced readers. The final diagnosis was based on histopathological studies or microbiological culture (eighteen patients) or on clinical findings after at least six months of follow-up (forty-two patients). Results: On the final composite assessment, twenty-five patients had infection and thirty-five did not. All twenty-five infections were correctly identified by both readers. There were four false-positive findings; in two of these cases, surgery had been performed less than six months prior to the study. The sensitivity, specificity, and accuracy were 100%, 88%, and 93% for the whole group; 100%, 90%, and 94% for the subgroup of patients with a suspected infection of the central skeleton; and 100%, 86%, and 93% for the subgroup of patients with a suspected infection of the peripheral skeleton. Interobserver agreement was excellent (kappa = 0.97). Conclusions: Fluorine-18 fluorodeoxyglucose-positron emission tomography is highly accurate as a single technique for the evaluation of chronic musculoskeletal infections. It is especially valuable in the evaluation of the central skeleton, where white blood-cell scans are less useful. Because of its simplicity and high degree of accuracy, it has the potential to become a standard technique for the diagnosis of chronic musculoskeletal infections. Further studies are needed to assess its ability to identify infections at the sites of total joint replacements and to distinguish infection from aseptic loosening of these prostheses.

The anti-tumoral activity of neoadjuvant intra-arterial 131I-lipiodol treatment for hepatocellular carcinoma: a pilot study.

BACKGROUND The high recurrence rate after curative resection has stimulated the development of adjuvant treatment modalities, such as local embolization. This study was set up to investigate the anti-tumoral potential of neo-adjuvant 131I-lipiodol administration before liver transplantation. METHODS In this preliminary, prospective study we treated 10 consecutive HCC patients by intra-arterial injection of 131I-lipiodol into the hepatic artery followed by liver transplantation within 1-9 months (mean 3.4). After hepatic catheterization, 1332-2146 MBq (mean 1887 MBq) or 36-58 mCi (mean 51 mCi) was instilled as selective as possible, depending on the distribution of the tumors: non-selectively in the hepatic artery propria (n = 4), selectively in the right and/or left hepatic artery (n = 3) or super-selectively in segmental arteries (n = 3). RESULTS Anti-tumoral activity was regarded as obvious with 1) a strong decrease of alfa-fetoprotein (AFP), comparing the highest recorded value before and after 131I-lipiodol and/or 2) a downstaging in TNM classification on the posttherapy MRI as compared to the pre-therapy MRI and/or 3) tumors with > 50% necrosis on histo-pathology of the explanted liver, without previous chemoembolization. Either of these criteria were met by 5/10 (50%) of patients. A 4) downstaging in pTNM classification on histopathology compared to the TNM classification of the MRI and/or a 5) tumor necrosis of only 10-50% were regarded as possibly tumor-related but were not accepted as a single criteria of anti-tumoral activity. This was seen in 3/10 (30%) of patients. Clinical side-effects of the 131I-lipiodol therapy were generally mild with a temperature rise in two cases, nausea without vomiting in another two and upper back pain in one patient. In one patient progressive liver failure developed one week after 131I-lipiodol therapy necessitating premature liver transplantation after 4 weeks. CONCLUSION With the use of stringent anti-tumoral criteria, this study shows evidence of an anti-tumoral effect in 50% of patients. Our data support the evaluation on larger patient numbers to confirm the promising anti-tumoral activity of 131I-lipiodol in HCC patients candidated for liver transplantation.

Visualization of the stomach on rhenium-186 HEDP imaging after therapy for metastasized prostate carcinoma

Post-therapeutic rhenium-186 HEDP scintigraphy revealed unexpected tracer uptake in the stomach of a 69-year-old man with prostate carcinoma. Because serum calcium and phosphate values were normal and bone scintigraphy showed no abnormal soft tissue uptake, microcalcifications in the stomach are unlikely to explain the abnormal tracer uptake. More likely, because visualization of the stomach is usually a result of trapping of free pertechnetate and because both rhenium and technetium are group VII metals, this finding was attributed to trapping of free perrhenate.

PET imaging using gamma cameras

This paper will review the recent advances and future developments in the field of coincidence imaging of positron emitters with a conventional Anger-type gamma camera. FDG imaging has shown high clinical importance in cardiology, neurology and especially oncology. Since access to full ring PET is mainly limited to university hospitals, there have been new developments allowing PET imaging on the standard Anger gamma camera. First the principles of coincidence imaging on a gamma camera will be reviewed. We will discuss the limitations of this technique, and the techniques used to partly overcome these limitations. The different configurations of the gamma camera operating in coincidence mode are pointed out. Different corrections for image degrading effects and reconstruction methods are evaluated in the final part.

Quality of life assessment in radionuclide therapy: a feasibility study of the EORTC QLQ-C30 questionnaire in palliative 131I-lipiodol therapy

Abstract. The good tolerance of radionuclide therapy has frequently been proposed as a major advantage. This study explored the feasibility of using the EORTC QLQ-C30 questionnaire in palliative iodine-131 lipiodol therapy for hepatocellular carcinoma. Questionnaires were completed during interviews in which all symptoms, co-morbidity and medication were assessed at baseline within 1 week before 131I-lipiodol therapy, and subsequently after 1 and 3 months, in 20 patients treated with locoregional, intra-arterial 131I-lipiodol therapy with or without cisplatin. Principal observations were that (1) a number of important scales, i.e. overall quality of life, physical functioning and pain, worsened between 0 and 3 months after 131I-lipiodol therapy, irrespective of tumour response, and (2) the occurrence of clinical side-effects was associated with a negative impact on quality of life and physical functioning 1 and 3 months after 131I-lipiodol. The QLQ-C30 can be regarded as a feasible method for quality of life assessment in 131I-lipiodol therapy for hepatocellular carcinoma and possibly in other radionuclide therapies. These observations should be related to the impact of other treatment modalities on quality of life.

57Co-EDTA renal imaging in rats.

We studied the synthesis of 57Co-EDTA (Eγ = 122 keV), its biodistribution in Wistar rats and its blood and urinary elimination compared with that of 51Cr-EDTA. We added 6 μmol EDTA diluted in 3-5 ml isotonic phosphate buffer (Na2HPO4) to a commercial 57CoCl2 radioactive tracer solution. The incubation period was 15 min. Quality control was performed using TLC and HPLC. Six healthy Wistar rats underwent 57Co-EDTA renography for 30 min. In one rat, additional TLC and HPLC was performed on blood (one sample only) and urine samples (n = 3) obtained 30 min, 30 min, 2 h and 4 h following injection of 18.5 MBq 57Co-EDTA and 51Cr-EDTA respectively. Radioisotope quantification was done by means of a germanium detector. 57Co was chelated to EDTA at high yield (Kstab = 10E36). No free or protein-bound 57Co was found. The ratio of 51Cr-EDTA to 57Co-EDTA remained constant (P = 0.133, n = 4). 57Co-EDTA was rapidly cleared from the blood pool (heart), and prompt and high target-to-background ratios for both kidneys were obtained (mean = 8.4, range = 7-12). At the end of the acquisition, activity remaining in the body excluding kidney and bladder was 45±5.2%. No specific activity uptake was noted in any other organ or tissue. We conclude that 57Co-EDTA is a promising radioligand for simultaneous clearance and separate renal function estimation. Its preparation is straightforward and, in rats, no free or protein-bound 57Co was found.

Tc-99m MDP uptake in herniated stomach tissue.

A 50-year-old woman with midthoracic pain was referred for bone scintigraphy to exclude vertebral disease. Although planar and tomographic images of the spine revealed no vertebral abnormalities, increased Tc-99m MDP uptake was found in a prevertebral thoracic mass corresponding to herniated stomach tissue as shown by computed tomography. In the abssnce of infrediaphragmatic stomach visualization, gastric trapping of unreduced pertechnetate cannot explain this finding. In addition, chemical binding to hydroxyapatite crystals and amorphous salt, as seen in long-standing metastatic caloification, may not explain this because computed tomography revealed no calcifications. Instead, local tissue anoxia with increased lactate production and pH reduction resulting in an increased tissue affinity for Tc-99m MDP should be considered.