Imene Zerizer

Role of FDG-PET and PET/CT in the diagnosis and management of vasculitis

PURPOSEnto investigate the role of FDG-PET and PET/CT in the evaluation of vasculitis.nnnMATERIALS AND METHODSna systematic revision of the papers published in PubMed/Medline until December 2009 was done.nnnRESULTSnFDG-PET and PET/CT have been proven to be valuable in the diagnosis of large-vessel vasculitis, especially giant cells arteritis with sensitivity values ranging 77% to 92%, and specificity values ranging 89% to 100%. In particular, FDG-PET/CT has demonstrated the potential to non-invasively diagnose the onset of the vasculitis earlier than traditional anatomical imaging techniques, thus enabling prompt treatment. False positive results mainly occur in the differential diagnosis between vasculitis and atherosclerotic vessels in elderly patients. Another area where FDG-PET/CT is gaining wider acceptance is in monitoring response to therapy; it can reliably detect the earliest changes of disease improvement post-therapy, and persistent activity is an indicator of non-responders to therapy. A few data have been reported about medium/small vessel vasculitis.nnnDISCUSSIONnFDG-PET and PET/CT have proven utility: (a) in the initial diagnosis of patients suspected of having vasculitis particularly in those who present with non-specific symptoms; (b) in the identification of areas of increased FDG uptake in which a biopsy should be done for obtaining a diagnosis; (c) in evaluating the extent of the disease; (d) in assessing response to treatment.

The role of early 18F-FDG PET/CT in prediction of progression-free survival after 90Y radioembolization: comparison with RECIST and tumour density criteria

PurposeThis study evaluated the ability of 18F-FDG PET/CT imaging to predict early response to 90Y-radioembolization in comparison with contrast-enhanced CT (CECT) using RECIST and lesion density (Choi) criteria. Progression-free survival (PFS) in patients with liver metastases at 2xa0years and decline in tumour markers were the primary end-points of the study.MethodsA total of 121 liver lesions were evaluated in 25 patients (14 men, 11 women) with liver-dominant metastatic colorectal cancer who underwent 18F-FDG PET/CT and CECT before and 6–8xa0weeks after treatment. Changes in SUVmax, tumour density measured in terms of Hounsfield units and the sum of the longest diameters (LD) were calculated for the target liver lesions in each patient. The patient responses to treatment were categorized using EORTC PET criteria, tumour density criteria (Hounsfield units) and RECIST, and were correlated with the responses of tumour markers and 2-year PFS using Kaplan-Meier plots and the log-rank test for comparison. Multivariate proportional hazards (Cox) regression analysis was performed to assess the effect of relevant prognostic factors on PFS.ResultsUsing 18F-FDG PET/CT response criteria, 15 patients had a partial response (PR) and 10 patients had stable disease (SD), while using RECIST only 2 patients had a PR and 23 had SD. Two patients had a PR, 21 SD and 2 progressive disease using tumour density criteria. The mean changes in SUVmax, sum of the LDs and tumour density after treatment were 2.9u2009±u20092.6, 7.3u2009±u200914.4xa0mm and 1.9u2009±u200913.18xa0HU, respectively. Patients who had a PR on 18F-FDG PET/CT had a mean decrease of 44.5xa0% in SUVmax compared to those with SD who had a decrease of only 10.3xa0%. The decreases in SUVmax and sum of the LDs were significant (pu2009<u20090.0001, pu2009<u20090.05, respectively) while the decrease in tumour density was not (pu2009>u20090.1065). The responses on the 18F-FDG PET/CT studies were highly correlated with the responses of tumour markers (pu2009<u20090.0001 for LDH, pu2009=u20090.01 for CEA and pu2009=u20090.02 for Ca19-9), while the responses on the CECT studies using both RECIST and tumour density criteria were not significantly correlated with the responses of tumour markers. The responses on 18F-FDG PET/CT studies also significantly predicted PFS (the median PFS in those with a PR was 12.0xa0months and in those with SD was 5xa0months, pu2009<u20090.0001), while RECIST and tumour density did not significantly predict PFS. Multivariate analysis demonstrated that responses on 18F-FDG PET/CT studies and decreases in SUVmax of ≤2.0 were the strongest predictors of PFS.ConclusionEarly response assessment to 90Y-radioembolization using 18F-FDG PET/CT is superior to RECIST and tumour density, demonstrating a correlation with tumour markers and significantly predicting PFS in patients with liver metastases. This could enable early response-adapted treatment strategies to be employed.

Semiquantitative Analysis and Characterization of Physiological Biodistribution of 68ga-dota-tate Pet/ct

Abstract The aim of this study was to describe the normal physiological distribution of 68Ga-DOTA-TATE using the SUV to reflect the density of somatostatin receptors in various organ systems. Methods A total of 250 patients (90 men and 160 women) were imaged on a Biograph 64 PET/CT TruePoint (Siemens Medical Solutions) 60 to 80 minutes after injection of 120 to 200 MBq (3.2-5.4 mCi) of 68Ga-DOTA-TATE. Visual assessment was performed on all studies on the multimodality workstation, and sites of increased uptake were recorded. The SUVmax was also calculated for each organ demonstrating increased 68Ga-DOTA-TATE uptake. Results Visual assessment of the 68Ga-DOTA-TATE PET/CT studies revealed increased uptake in the pituitary, salivary, thyroid glands, liver, spleen, adrenals, kidneys and bone reflecting normal increased somatostatin receptor expression. These sites were confirmed to be disease free on clinical follow-up and on correlation with other imaging (CT/MRI/ultrasound). Using semiquantitative analysis, SUVmax values were the highest in the pituitary gland [11 (4.5)], spleen [18.9 (6.6)], adrenal [14.0 (5.6)], and kidneys [14.2 (3.6)]. In addition, increasing uptake in the uncinate process of pancreas was noted in 12% of patients with SUVmax of 9.2 (3.3). Moderate 68Ga-DOTA-TATE uptake was also present in salivary gland [3.4 (1.8)], thyroid [2.9 (1.2)], and normal liver [6.5 (2.2)]. The bones generally showed low 68Ga-DOTA-TATE uptake with an SUVmax of 1.0 (0.3). Conclusions Knowledge of the normal 68Ga-DOTA-TATE distribution is highly important for accurate interpretation of this novel imaging modality, which is increasingly being used in the imaging of neuroendocrine tumor.

Occult squamous cell carcinoma of the uvula detected by F-18 FDG PET/CT in a case of carcinoma of unknown primary in the head and neck.

Incidence of unknown primary head/neck tumors with metastatic cervical lymphadenopathy at time of diagnosis is approximately 2% to 9%. Detecting site of original disease is challenging. We present a 75-year-old woman with bulky unilateral level 2 and 3 lymphadenopathy. Clinical examination and computed tomography (CT) did not reveal detectable abnormalities except neck-node metastases; biopsy indicated metastatic squamous cell carcinoma (SCC). F-18 FDG PET/CT imaging was performed to detect the primary tumor site, which revealed a small metabolically-avid lesion in uvula, biopsy demonstrated SCC, the origin of metastatic disease. F-18 FDG PET/CT imaging of unknown primary head/neck tumors can have positive impact in identifying small occult primary tumor foci.

The Labeled-Leukocyte Scan in the Study of Abdominal Abscesses

AimThe purpose of the present paper was to review the literature over the last 30xa0years to assess the value of radionuclide imaging, particularly labeled leukocyte scan, as compared to other imaging modalities in the management of abdominal abscesses.MethodsA systematic review of the published studies in humans cited in PubMed written in English, French, German, Italian, and Spanish was made.ResultsUltrasound (US) has lower sensitivity than leukocyte scan (LS), particularly in patients without localizing signs, while CT has higher sensitivity than US, but less than LS. On the other hand, CT had higher specificity than both LS and US.DiscussionLS is the more sensitive method to localize abdominal abscesses and may guide dedicated US and CT investigations to improve their diagnostic potential. Further diagnostic evolution is expected from the routine use of hybrid SPECT/CT systems.

The Role of PET/CT in Advanced Malignant Melanoma

Positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose demonstrates a high sensitivity and specificity for detecting both locoregional and distant metastases in patients presenting with AJCC stages III and IV disease. PET/CT also plays an important role in the detection of recurrence particularly in high-risk group patients, and this should be the modality of choice in investigating patients for suspected recurrence. The role of PET/CT in response assessment and follow-up still has to be defined, and cost-effectiveness analysis is required to strengthen its role.

Don’t blame the bones!

An 83-year-old woman who was under treatment for a community-acquired pneumonia presented with dehydration, generalized myalgia, proximal lower limb weakness and associated hypercalcaemia. A 99m Tc HDP (hydroxymethylene diphosphonate) 600-MBq whole-body bone scan performed to exclude bony metastases demonstrated no bone lesions, but showed abnormal intense soft-tissue activity in the shoulder and pelvic girdle musculature, findings suggestive of a proximal myopathy. She had been treated with the antibiotics co-amoxiclav and clarithromycin for 14 days, and in addition was on a regular dose of

Fanti S, Farsad M, Mansi L (eds): Atlas of PET/CT: A quick guide to image interpretation

The use of PET/CT is increasingly becoming routine in many institutions, particularly in the field of oncology. There has also been a surge in the demand for PET/CT case-based reviews and atlases to fulfil the increasing need for educational and training reviews that can aid practitioners in image interpretation. The atlas currently being reviewed aims at a broad spectrum of physicians, ranging from technicians, junior radiology and nuclear medicine trainees, to qualified consultants. The book is user-friendly with a clear layout that divides its 288 pages into two main sections. The first section illustrates normal and benign findings of PET/CT, highlighting common and rare pitfalls that the practitioner needs to be aware of whilst interpreting the studies. It is divided into three chapters. The first chapter discusses the normal distribution of FDG in the body illustrated with clinical cases and technical aspects. The second chapter highlights the importance of contrastenhanced PET/CT in the staging of certain tumours. The third chapter describes the pitfalls, based on anatomical locations, that can reduce the sensitivity and specificity of PET/CT. The second section contains more than 500 images of pathology on PET/CT illustrated as black-and-white CT and PET images as well as fusion images. This is cleverly presented as case-based reviews that the reader can utilize as problem-solving tools. This second section (chapter 4) reviews the different cancers with a case-based practical approach that can be easily applied clinically. The images are clear, relevant and well annotated with arrows and legends. The cases emphasize the role of PET/CT in making the diagnosis, staging, follow-up and assessment of recurrence. The cases are also extremely contemporary with an emphasis on some innovative techniques such as the use of C-CHOL PET/CT in prostate cancer, and also the usefulness of PET/CT in debatable areas such as melanoma and sarcomas is reviewed. Overall the atlas provides a concise but at the same time comprehensive aid to the interpretation of a variety of pathological processes on PET/CT encountered in routine clinical practice. A major strength of this book is the take-home messages presented at the end of each page as teaching points in highlighted boxes. This is a fantastic aide-mémoire for the practitioner. Although the use of PET/CT in oncology is extensively reviewed in the atlas, other applications of PET/CT such as in neuroimaging are not covered. This was perhaps beyond the scope of this book. Overall, the authors present us with an efficient, userfriendly, well-written and illustrated atlas that any practitioner can utilize in their daily practice in the interpretation of PET/ CT images in oncology. Eur J Nucl Med Mol Imaging (2009) 36:879 DOI 10.1007/s00259-009-1070-8