Periurethral Mass Mimicking Neoplasm After Injection of Macroplastique for Postprostatectomy Stress Incontinence: A Pitfall on 18F-FDG PET/CT.

A 64-year-old man underwent initial F-FDG PET/CT staging for gastric cardia adenocarcinoma, which showed the primary gastric tumor, several bone metastases, and high uptake in a periurethral mass mimicking pelvic neoplasm developed after injection of polydimethylsiloxane (Macroplastique) urethral bulking agent 6 years ago for postprostatectomy stress urinary incontinence. This case showed a very rare complication of silicon particle injection therapy, and the intense uptake is likely due to granulomatous reaction around the implant.

Everolimus-induced pulmonary toxicity: Findings on 18F-FDG PET/CT imaging.

The everolimus-exemestane combination is indicated in advanced breast cancer treatment and usually well tolerated. The objective of the study was to determine the frequency of everolimus lung side effects and investigate their imaging characteristics on positron emission tomography with 18F-fluoro-deoxy-glucose combined with computerized tomography (F-FDG PET/CT).Our single-center retrospective descriptive study systematically included all patients with metastatic breast cancer treated by this combination (n = 29 representing 57 F-FDG PET/CT). Number of segments involved was quantified. Maximum standardized uptake value (SUVmax), average standardized uptake value (SUVmean), metabolic target volume (MTV), and total lesion glycolysis (TLG) were measured. Severe pneumopathy was studied by subgroup analysis.Pleuroparenchymal anomalies rate detected on F-FDG PET/CT was 62%. Alveolar-interstitial lesions were mainly observed (89%) and affected 2.8 segments (0.5-11.5) with a median of 2 segments. S7 and S10 were the most involved segments with SUVmax 3.9 (1.3-8.8) and SUVmean 2.2 (0.7-4.9). Statistically significant difference (P = .02) was found with number of segment involved to characterize severe pneumopathy (average of 6.3 segments [2.5-11.5] vs 1.9 segments [0.5-8] for interstitial lung disease) but not with SUVmax, SUVmean, MTV, TLG (P = .14, 0.22, 0.22, and 0.17, respectively).The F-FDG PET/CT could highlight pulmonary everolimus side effects, with a typical imaging pattern: alveolar-interstitial opacities associated with moderate uptake, more or less extensive, mainly affecting the lower lobes. Rarely, a pseudotumoral aspect may be detected, corresponding to a pitfall. MTV or TLG showed a tendency to differentiate severe pneumopathy vs interstitial lung disease but no statistically significant differences was observed contrarily to the number of segments involved. Further studies are necessary to determine if the F-FDG PET/CT could early predict adverse effects of mTOR inhibitors.

Incidental Detection of Oxyphilic Papillary Thyroid Carcinoma by 18F-Fluorocholine PET/CT.

A 70-year-old man with prostate cancer and increased prostate-specific antigen level of 55 ng/mL underwent staging F-fluorocholine PET/CT, which demonstrated the primary prostate tumor and a focal area corresponding to a 2-cm hypodense nodule in the left thyroid lobe. Fine-needle aspiration and subsequent total thyroidectomy with central lymph node dissection showed an oxyphilic papillary thyroid carcinoma and a medullary microcarcinoma. Oxyphilic tumors represent a significant proportion of the few case reports of incidental focal thyroid fluorocholine thyroid uptake.

Prognostic value of (18)F-FDG PET/CT metabolic parameters in metastatic differentiated thyroid cancers.

PURPOSE: To evaluate the prognostic value of F-fluorodeoxyglucose positron emission tomography (FDG PET) with quantitative analysis using metabolic parameters in metastatic differentiated thyroid cancer (DTC). MATERIALS AND METHODS: The FDG-PET scans of 37 patients with metastatic DTC were studied retrospectively. The number of FDG-avid lesions, the SUVmax, the SULpeak of the lesion with the highest FDG uptake, the overall metabolic tumor volume (MTV), and the total lesion glycolysis (TLG) were measured. Curves of progression-free survival (Kaplan-Meier) and Cox univariate and multivariate analyses determined the prognostic factors for survival. RESULTS: Progression-free survival was better in patients with less than 10 FDG-avid lesions (P = 0.0089), the SUVmax less than 10 (P = 0.0026), the SULpeak less than 5 (P = 0.0004), and the TLG less than 154 (P = 0.0110).Cox analyses showed that only the result of the PET scan was predictive of survival (age, TNM stage, histology, and the I whole body radioiodine scan were not associated with prognosis). In the univariate analysis, prognostic factors for progression-free survival and overall survival were the SUVmax (P = 0.004; P = 0.018), the SULpeak (P = 0.001; P = 0.017), and the TLG (P = 0.014; P = 0.012). The number of FDG-avid lesions was significantly associated with progression-free survival (P = 0.012), but not the MTV. In the multivariate analysis, the number of FDG-avid lesions and the SULpeak were independent prognostic factors. CONCLUSIONS: FDG PET using metabolic parameters is a prognostic factor in metastatic DTC. It could improve the therapeutic management and follow-up of patients.

Incidental finding of F-18 FDG skin uptake in a patient with psoriasis during the evaluation of a recurrent papillary thyroid carcinoma.

We report the case of a patient, referred in our institution for a PET/CT for a suspected recurrence of papillary thyroid carcinoma. An intense cutaneous uptake of FDG was seen in the upper neck region. The clinical examination showed an indurate and thickened red descamative plaque evocative of psoriasis, and the patient reported a long history of psoriatic lesions of the skin, evolving for many years. This case illustrates an incidental finding which must be recognized, and not confounded with other causes of skin uptake. The FDG image is not surprising, as FDG uptake is expected in active inflammatory disease.

Single-photon emission computed tomography combined with computed tomography (SPECT/CT) in bone diseases.

Radionuclide bone scanning was proven effective many years ago. Its main advantages are good sensitivity, limited radiation exposure, and noninvasiveness. However, increased radionuclide uptake by a lesion is not specific, and differentiating malignant from nonmalignant disorders may therefore be difficult. An additional structural imaging study is often needed to establish the final diagnosis. Furthermore, the limited resolution of radionuclide bone scanning images does not allow accurate localization of the lesions. Single-photon emission computed tomography (SPECT) combined with computed tomography (CT) provides both structural and functional information. SPECT/CT has been proven useful for interpreting radionuclide bone scan results in patients with bone malignancies, showing far better specificity than planar imaging or SPECT alone, most notably in the evaluation of spinal abnormalities. SPECT/CT provides an accurate evaluation of the site of the lesions and also supplies other information that can be useful in nonmalignant conditions such as injuries, infections, and degenerative disease. Nevertheless, there are only a few published studies on the usefulness of SPECT/CT in nonmalignant conditions. However, SPECT/CT is only starting to become available and may become a routine investigation for a number of rheumatic disorders.

Positron Emission Tomography in oncology: present and future of PET and PET/CT.

PET is a crucial technique in molecular imaging, allowing in vivo assessment and localization of pathological processes, thanks to its ability to detect very small amounts of radioactive molecules. This is of particular interest in oncology where abnormal metabolism or synthesis in tumor cells but also various tumor characteristics can be studied using this nuclear medicine technique. FDG is currently the most widely used tracer, nowadays essential in the management of various malignancies, with large applications in diagnosis, initial assessment, therapy monitoring, and recurrence detection. The combination of anatomical information provided by PET/CT further increased its interest. Beyond its spread use in daily practice, future applications of PET will involve other tracers than FDG and develop research applications in humans as well as in small animals.