Jérémie Calais

Areas of High 18F-FDG Uptake on Preradiotherapy PET/CT Identify Preferential Sites of Local Relapse After Chemoradiotherapy for Non–Small Cell Lung Cancer

The high rates of failure in the radiotherapy target volume suggest that patients with stage II or III non–small cell lung cancer (NSCLC) should receive an increased total dose of radiotherapy. Areas of high 18F-FDG uptake on preradiotherapy 18F-FDG PET/CT have been reported to identify intratumor subvolumes at high risk of relapse after radiotherapy. We wanted to confirm these observations on a cohort of patients included in 3 sequential prospective studies. Our aim was to assess an appropriate threshold (percentage of maximum standardized uptake value [SUVmax]) to delineate subvolumes on staging 18F-FDG PET/CT scans assuming that a smaller target volume would facilitate isotoxic radiotherapy dose escalation. Methods: Thirty-nine patients with inoperable stage II or III NSCLC, treated with chemoradiation or with radiotherapy alone, were extracted from 3 prospective studies (ClinicalTrials.gov identifiers NCT01261585, NCT01261598, and RECF0645). All patients underwent 18F-FDG PET/CT at initial staging, before radiotherapy, during radiotherapy, and during systematic follow-up in a single institution. All 18F-FDG PET/CT acquisitions were coregistered on the initial scan. Various subvolumes in the initial acquisition (30%, 40%, 50%, 60%, 70%, 80%, and 90% SUVmax thresholds) and in the 3 subsequent acquisitions (40% and 90% SUVmax thresholds) were pasted on the initial scan and compared. Results: Seventeen patients had a local relapse. The SUVmax measured during radiotherapy was significantly higher in locally relapsed tumors than in locally controlled tumors (mean, 6.8 vs. 4.6; P = 0.02). The subvolumes delineated on initial PET/CT scans with 70%–90% SUVmax thresholds were in good agreement with the recurrent volume at a 40% SUVmax threshold (common volume/baseline volume, 0.60–0.80). The subvolumes delineated on initial PET/CT scans with 30%–60% SUVmax thresholds were in good to excellent agreement with the core volume of the relapse (90% SUVmax threshold) (common volume/recurrent volume and overlap fraction indices, 0.60–0.93). The agreement was moderate (>0.51) when a 70% SUVmax threshold was used to delineate on initial PET/CT scans. Conclusion: High 18F-FDG uptake areas on pretreatment PET/CT scans identify tumor subvolumes at greater risk of relapse in patients with NSCLC treated by concomitant chemoradiation. We propose a 70% SUVmax threshold to delineate areas of high 18F-FDG uptake on initial PET/CT scans as the target volumes for potential radiotherapy dose escalation.

18F-FDG PET/CT scan in malignant priapism with diffuse pulmonary adenocarcinoma metastatic invasion of both corpus spongiosum and cavernosum

A 60-year-old man with a left upper lobe pulmonary mass discovered during a pulmonary embolism examination was referred for an F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT scan for initial staging. He had a recent 3-day history of priapism, without any mass, ulceration or swelling of the penis. A wholebody F-FDG PET/CT scan was performed 80 min after injection of 215.7 MBq of F-FDG. Intense increased F-FDG uptake was observed in the left upper lobe pulmonary tumour, the adrenal glands, the pancreas, the para-aortic lymph nodes and the penis, corresponding to a multimetastatic pulmonary cancer (a). The uptake in the enlarged penis was very intense (maximum standardized uptake value=17.5), diffuse and homogeneous, in both the entire corpus spongiosum and cavernosum (b, c). Biopsies performed on the pulmonary mass revealed a pulmonary adenocarcinoma. Biopsies performed during surgery of the penis led to the diagnosis of a massive and diffuse invasion of both corpus spongiosum and cavernosum by proliferating pulmonary adenocarcinoma cells. Local surgical interventions for priapism, cavernospongious fistulae and bore of the corpus cavernosum were unsuccessful due to the massive and diffuse nature of the proliferation as it was seen on the diffuse F-FDG uptake. After this exam, partial response to chemotherapy was observed, but the patient died 3 months later. Metastatic lung tumours to the penis have already been described but are rare [1]. Penile metastasis usually indicates widespread metastatic disease and is an extremely bad prognostic sign with a poor outcome (mean survival time of 3.5 months [2]). F-FDG uptake in the penis has been described in conditions such as primary malignancy of the penis, lymphoma and dilated urethra [3]. In this case, this F-FDG PET/CT scan explained why local surgical interventions were unsuccessful, by showing the diffuse invasion in the whole corpus cavernosum and spongiosum, which could have allowed earlier and better adapted chemoor radiotherapy.

Tc-99m-HMPAO-Labeled Leukocyte SPECT/CT in Pediatrics: Detecting Candida albicans Tricuspid Endocarditis

An immunocompromised 12-year-old girl with a third episode of recurrent severe sepsis and endocarditis suspicion was referred to our center to undergo Tc-HMPAO radiolabeled autologous granulocyte scintigraphy (WBC scan). The patient was treated for cortico-resistant ulcerative colitis with immunosuppressive drugs (infliximab and aziathropine) for 3 months. For 1 month, she received a large probabilistic multiple antibiotic therapy for the two first episodes of severe sepsis. The first one was due to a gramnegative bacillus and yeast, with a right jugular catheter infection. The right jugular catheter was removed, and a second catheter in the left jugular vein was then placed. The second severe sepsis was due to enterobacter and Pseudomonas aeruginosa. No deep infection center was found: abdominal US, renal US, abdomino-pelvic injected CT (deep abscess suspicion), bone scan, cervical MRI (spondylodiscitis suspicion), jugular vein Doppler US (left jugular catheter thrombosis infection suspicion) and transthoracic echocardiography all remained negative. Transesophageal echocardiography (TEE) was avoided because of the young age [1]. The blood count showed leukocytosis (14 g/l) with neutrophilia (8.3 g/l). Planar images obtained 4 h (a, b) and 24 h (c, d) after injection of 360 MBq of Tc-HMPAO radiolabeled autologous granulocytes, according to the guidelines from the European Association of Nuclear Medicine [2], showed no focal pathological uptake (Fig. 1). Thoracic SPECT-CT performed 24 h after injection showed focal uptake in the projection of the tricuspid valve (e, f, g, h). Multiple bilateral and peripheral pulmonary micronodules were seen on SPECT-CTwith the lung window setting (i, j), without significant associated activity. Multiple bilateral peripheral subpleural distribution and lower zone predication, feeding vessel sign, pleural effusions, poor margination and variation in size of the micronodules, which is a reflection of repeated episodes of embolic shower, were CT signs suggesting septic emboli [3]. The absence of activity in the micronodules can be explained by the low spatial resolution of SPECT. Indeed, the lung CT anomalies are more traducing distal small infarcts caused by septic emboli than infectious lung destruction [3]. These results led to performing TEE, which showed tricuspid vegetation. Blood cultures were then positive to Candida albicans. Control blood cultures and TEE performed 6 weeks later after adapted antifungal therapy remained negative. Pediatric fungal tricuspid endocarditis is a rare and severe pathology that can provide negative blood cultures, falsenegative echocardiography and also false negative WBC scans [4, 5]. In the study of Erba et al. [4], the false-negative findings for Candida or Enterococcus species, which may be explained by the ability of thesemicroorganisms (and others such as Staphylococcus epidermidis) to form a biofilm resulting in resistance to antimicrobial treatment, altered neutrophil recruitment and escape from the host defense mechanisms. However, in this child with several identified risk factors such as a vascular l ine, mult iant ibiot ic use and ISSN (print) 1869-3474 ISSN (online) 1869-3482