Tarik Belhocine

Imaging of large vessel vasculitis with (18)FDG PET: illusion or reality? A critical review of the literature data

Fluorine-18 fluorodeoxyglucose positron emission tomography (18FDG PET) plays a major role in the management of oncology patients. Owing to the singular properties of the glucose tracer, many patients suffering from non-malignant diseases such as inflammatory or infectious diseases may also derive clinical benefit from the appropriate use of metabolic imaging. Large vessel vasculitides such as giant cell arteritis and Takayasu arteritis are other examples that may potentially extend the field of 18FDG PET indications. The purpose of the present article is to assess the feasibility of metabolic imaging in vasculitis on the basis of the current literature data. In particular, the clinical context and the 18FDG imaging patterns seen in patients with large vessel vasculitis are analysed in order to identify potential indications for metabolic imaging.

Whole-body positron emission tomography using fluorodeoxyglucose in patients with metastases of unknown primary tumours (CUP syndrome).

The aim of this study was to evaluate the clinical performances of whole body 2-[18F]fluorodeoxyglucose positron emission tomography (FDG PET) imaging for the detection of the primary tumour in patients with metastases of unknown origin. Forty-one patients, without previous history of known cancer (18 women and 23 men; average age 64.1 years) with metastasis confirmed by histopathological analysis were included in a retrospective study. Results of PET were compared with those of techniques used in the current conventional diagnostic procedure. All known metastatic lesions were detected by PET. There were 26 true-positive and two false-negative results. Primary tumour remained undetermined in eight patients after conventional investigations and PET. PET was superior to conventional diagnostic procedure in 11 patients and led to modify treatment in 11 patients. Sensitivity of PET was superior than computed tomography in detecting abdominal primary tumours. FDG PET is useful in patients with unknown primary tumour because its sensitivity is good and it could modify the disease management. Otherwise, PET allows the evaluation of the extent of the disease and could be used to monitor treatment efficiency. Its contribution has to be evaluated particularly in patients with primary tumour with a specific treatment.

In Vivo Imaging of Chemotherapy-Induced Apoptosis in Human Cancers

Abstract: Rationale. Induction of apoptosis in sensitive tumor cells is the main mechanism of action of chemotherapy agents in human cancers. Also, the assessment of drug‐induced apoptosis soon after chemotherapy may be an early predictor of treatment efficacy.

99m Tc-Annexin A5 Uptake and Imaging to Monitor Chemosensitivity

Most anticancer agents act by inducing apoptosis in sensitive tumor cells. Hence, in many types of cancers, significant increase of tumor apoptosis after chemotherapy correlates with tumor chemosensitivity. Theoretically, a reliable evaluation of apoptotic changes, postchemotherapy to baseline, may provide valuable insights into the apoptotic competence of cancers. Until now, assessment of chemosensitivity has usually relied upon histological evidence of tumor response (i.e., partial or complete disappearance of tumor cells) or demonstration of tumor shrinkage by means of morphological imaging (i.e., computed tomography or magnetic resonance imaging). In clinical practice, however, these conventional methods are proving ineffective for monitoring tumor chemosensitivity on a daily basis. Recent developments in molecular imaging have allowed the synthesis of a new radiolabeled agent, 99mTc-recombinant human Annexin A5, designed to the assessment of apoptotic response of cancers after a single course of chemotherapy. Such in vivo technique opens promising perspectives for evaluating, noninvasively and early, tumor response to anticancer therapies. Alternative methods for Annexin A5 labeling and imaging may improve the detection of drug-induced apoptosis to monitor chemosensitivity.

Transbilayer phospholipids molecular imaging

Nuclear medicine has become a key part of molecular imaging. In the present review article, we focus on the transbilayer phospholipids as exquisite targets for radiolabelled probes in molecular imaging. Asymmetry of phospholipid distribution is a characteristic of mammalian cell membranes. Phosphatidylcholine and sphyngomyelin cholinophospholipids are primarily located within the external leaflet of the cell membrane. Phosphatidylserine and phosphatidylethanolamine aminophospholipids, and also phosphatidylinositol are primarily located within the internal leaflet of the cell membrane. New radiolabelled tracers have been designed in preclinical and clinical research for PET-CT and SPECT-CT molecular imaging of transbilayer phospholipids.

An Appraisal of 18-Fluorodeoxyglucose Positron Emission Tomography for Melanoma Staging

Background: Positron emission tomography (PET scan) using fluorodeoxyglucose (FDG) is increasingly recognized as a reliable diagnostic method to detect metastases of malignant melanoma (MM). Objective: To compare the diagnostic performance of 18-FDG PET scan to that of conventional imaging. Methods: A total of 28 assessments were conducted in 24 patients at risk of metastatic MM. Results: The diagnostic accuracy was over 80% and similar for PET scan and conventional imaging. Conclusion: Both the specificity and sensitivity of PET scan are high although not perfect. Confrontation of data with anatomical location and clinicopathological findings remains mandatory.

The Imaging of Apoptosis with the Radiolabelled Annexin A5: A New Tool in Translational Research

Programmed cell death also called apoptosis plays a pivotal role in many physiological and pathological conditions. In the multi-step process of drug development, a number of medications are being designed to target strategic checkpoints of the apoptotic cascade either to induce or to inhibit programmed cell death. Conceptually, the assessment of programmed cell death in response to various therapeutic interventions appears to be critical for evaluating the efficacy of many drugs that act through apoptotic pathways. In the last decade, nuclear medicine techniques provided proofs of principle for the imaging of apoptosis both in vitro and in vivo. The purpose of this article was to review current knowledge on the imaging of apoptosis with radiolabelled annexin A5 in various pre-clinical and clinical models, and beyond that, to assess the potential integration of such a dedicated technology into translational research.

Differentiated thyroid cancer with epiphora: detection of nasolacrimal duct obstruction on I-131 SPECT/CT.

Chronic excess tearing or epiphora is seen in differentiated thyroid cancer patients who have received multiple doses of I-131 therapy. A 25-year-old woman with a papillary thyroid cancer received 6 doses of I-131 ( 37GBq) for I-131–avid lung metastases. The patient underwent a diagnostic I-131 whole-body scan plus SPECT/CT for a borderline thyroglobulin. I-131 whole-body scan demonstrated a right periorbital focus as shown in Figure 1, which was precisely localized on SPECT/CT at the right proximal nasolacrimal duct as shown in Figure 2. Dacryoscintigraphy documented a right high-grade obstruction as shown in Figures 3 and 4. The patient underwent a right dacryocystorhinostomy with a Crawford tube insertion. SPECT/CT allows anatofunctional definition of pathophysiological I-131 uptake patterns.

How Useful is an Integrated SPECT/CT in Clinical Setting and Research?: Evaluation of a Low Radiation Dose 4 Slice System §

Hybrid imaging is becoming a popular technology in nuclear medicine. We have evaluated the added value of an integrated SPECT/low-dose multislice CT over conventional planar/SPECT nuclear imaging. Phantom and clinical studies were performed on the Infinia™ Hawkeye™ 4 slice (HWK-4) with an upgraded software package (Xeleris 2.05v) from GE Heatlthcare to assess 1) the benefit of CT for contrast-resolution, attenuation correction, and anatomic localisation; 2) the impact of hybrid imaging in 456 consecutive patients in a clinical setting. SPECT/CT data were compared to conventional planar/SPECT data and correlated to clinical, biochemical, morphological imaging, angiography, and pathology findings. SPECT/CT was well tolerated by the patients with minimal CT irradiation dose (< 2mSv). HWK-4 provided useful attenuation correction for its routine use in MPI and accurate anatomic localisation of physiological and pathological foci in 99m Tc-RBC, 99m Tc-HMPAO-WBC, 131/123 I-MIBG, Octreoscan ® , and 67 Ga studies. Low-dose multislice CT also helped detect gross morphological abnormalities. Hybrid imaging had a significant impact in ProstaScint ® and parathyroid imaging for image-guided intervention. In bone imaging and differentiated thyroid cancers, SPECT/CT was able to clarify equivocal findings from planar whole-body scan. SPECT/CT was also found useful to precisely localize sentinel lymph nodes. Research protocols are being evaluated for half-time acquisition with resolution recovery and quantification of tracer distribution. SPECT/low-dose multislice CT has been successfully implemented in routine clinical practice. CT provided added value for effective attenuation correction and accurate anatomic localisation of disease with an impact on patient management.

Complementary roles of low-dose SPECT-CT and high-resolution volume CT for detection of coronary artery disease.

A 70-year-old woman with a high pretest likelihood of coronary artery disease (CAD) underwent a Tc-99m MIBI SPECT-CT study for myocardial perfusion imaging (MPI), which was complemented by a high-resolution volume CT (VCT) study. After attenuation correction, an MPI pattern of ischemia was detected in the lateral wall of the myocardium. The CT calcium score (CTCS) was above the 75th percentile. The CT angiography (CTA) demonstrated a 70% stenosis at the ostial part of the circumflex artery, and incidentally revealed a saccular aneurysm. In todays nuclear cardiology, low-dose SPECT-CT plus high-resolution VCT allows anatofunctional assessment of suspected CAD.