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At a time when reducing the radiation dose to patients and the public has become a major focus, we assessed the radiation exposure rate from patients after an 18 F-FDG PET/CT scan and evaluated different interventions to reduce it. Methods: We enrolled 100 patients, divided into 2 groups. For both groups, the radiation dose rate was measured with an ionization survey meter immediately after the scan. For group 1, the patients then voided and their dose rate was measured again. For group 2, the patients waited 30 min before voiding, and we measured the dose rate before (group 2A) and after (group 2B) they voided. Results: In total, 74 of the 100 patients exceeded the 20 μSv/h (2 mR/h) threshold immediately after the scan. In group 1, the mean dose rate decreased by 20.0% from the postscan measurement, with 12 of 36 remaining at or above 20 μSv/h. In group 2A, the mean dose rate decreased by 23% from the postscan measurement, with 9 of 38 remaining at or above 20 μSv/h. In group 2B, the mean dose rate decreased by 35% from the postscan measurement, with 1 of 38 remaining at 20 μSv/h. Conclusion: Nearly 75% of patients undergoing an 18 F-FDG PET/CT scan exceed 20 μSv/h when leaving the imaging facility. The most effective method to reduce radiation exposure was to have the patient void 30 min after the examination., (© 2020 by the Society of Nuclear Medicine and Molecular Imaging.)

A novel quality control and quality assurance device provides time-activity curves that can identify and characterize PET/CT radiotracer infiltration at the injection site during the uptake phase. The purpose of this study was to compare rates of infiltration detected by the device with rates detected by physicians. We also assessed the value of using the device to improve injection results in our center. Methods: 109 subjects consented to the study. All had passive device sensors applied to their skin near the injection site and mirrored on the contralateral arm during the entire uptake period. Nuclear medicine physicians reviewed standard images for the presence of dose infiltration. Sensor-generated time-activity curves were independently examined and then compared with the physician reports. Injection data captured by the software were analyzed, and the results were provided to the technologists. Improvement measures were implemented, and rates were remeasured. Results: Physician review of the initial 40 head-to-toe field-of-view images identified 15 cases (38%) of dose infiltration (9 minor, 5 moderate, and 1 significant). Sensor time-activity curves on these 40 cases independently identified 22 cases (55%) of dose infiltration (16 minor, 5 moderate, and 1 significant). After the time-activity curve results and the contributing factor analysis were shared with technologists, injection techniques were modified and an additional 69 cases were studied. Of these, physician review identified 17 cases (25%) of infiltration (13 minor, 3 moderate, and 1 significant), a 34% decline. Sensor time-activity curves identified 4 cases (6%) of infiltration (2 minor and 2 moderate), an 89% decline. Conclusion: The device provides valuable quality control information for each subject. Time-activity curves can further characterize visible infiltration. Even when the injection site was out of the field of view, the time-activity curves could still detect and characterize infiltration. Our initial experience showed that the quality assurance information obtained from the device helped reduce the rate and severity of infiltration. The device revealed site-specific contributing factors that helped nuclear medicine physicians and technologists customize their quality improvement efforts to these site-specific issues. Reducing infiltration can improve image quality and SUV quantification, as well as the ability to minimize variability in a site's PET/CT results., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

Plantar pain is a common problem endured by most adults at some point in their life that may result in considerable disability. Plantar fibromatosis is a locally invasive neoplasm, with the development of fibrous nodules on the plantar aspect of the feet, which can remain asymptomatic for years. (18)F-Fluorodeoxyglucose ((18)F-FDG) PET/CT has been more prevalent as the imaging modality of choice for cancer patients, but the imaged field of view is often from the base of the skull to the upper thighs. Therefore, the feet are typically not included in the field. However, true whole-body imaging from the top of the skull to the bottom of the feet is performed at some institutions and can provide clinically useful findings. One such finding is the presence of (18)F-FDG-avid plantar nodules. This review is intended to help clinicians become aware of these potential false-positive nodules that can affect a patient's staging and management.

Positron emission tomography (PET) using [(18)F]-2-deoxy-d-glucose (FDG) diagnoses, stages, and restages many cancers and is often better than anatomic imaging alone. However, abnormalities within the orbit present a challenge in evaluation, mainly due to the subtle findings on PET/computed tomography (CT). In addition, this region is typically at the edge of the field of view for the standard base of skull to upper thigh FDG-PET/CT scans. The aim of this pictorial essay is to illustrate several subtle and apparent abnormalities within the orbit that can have a profound impact on patient management and follow-up.

Unlabelled: (18)F-FDG muscle uptake is evident in some benign physiologic processes as seen in the respiratory muscles of patients with chronic obstructive pulmonary disease (COPD) and labored breathing. The purpose of this study was to correlate the presence of COPD with the patterns of (18)F-FDG uptake by muscles as demonstrated by PET/CT scans., Methods: (18)F-FDG PET/CT scans and pulmonary function tests (PFTs) were performed for 63 consecutive patients with newly diagnosed or highly suspected lung cancer. Presurgical pulmonary function tests by way of spirometry examinations were performed as the standard of care. Patients were grouped into those with normal spirometry findings and those with mild to very severe COPD. The guidelines of the Global Initiative for Chronic Obstructive Lung Disease were used for staging COPD and obstructive impairment. A nuclear medicine physician and 2 residents who did not know the COPD status retrospectively reviewed PET/CT scans and kept a log for cases of increased (18)F-FDG uptake in the respiratory muscles (diaphragm, intercostal muscles, and scalene muscles). The χ(2) test and Cramer V were used to evaluate the correlation between increased (18)F-FDG uptake by muscles and the presence of COPD., Results: Sixty-three patients underwent both (18)F-FDG PET/CT and PFT within 1 mo of each another without interval therapy. Of the 63 patients, 26 (41%) had no spirometric obstruction and 37 (59%) had spirometric obstruction. Of these, 30 (81%) had a previously established diagnosis of COPD (1 mild, 26 moderate, 9 severe, and 1 very severe). Excessive (18)F-FDG uptake was seen in at least 2 of the 3 muscles (diaphragm and intercostal muscles) in 27 (73%) of the 37 patients with COPD and obstructive ventilatory impairment. The severity of COPD and obstruction showed a significant correlation with the presence of abnormal (18)F-FDG uptake by any of the 3 muscle types, particularly when 2 groups of muscles were involved (Cramer V = 0.60, χ(2) P < 0.001)., Conclusion: Our study revealed a strong correlation between increased (18)F-FDG uptake by respiratory muscles and the presence of COPD.

Purpose: We retrospectively compared the maximum standard uptake value (SUVmax) of FDG PET in four different sites to evaluate whether a common diagnostic SUVmax threshold may exist in these tumor locations. We further postulate that the SUVmax thresholds are higher in thoracic lesions than in extrathoracic lesions., Material and Methods: N = 143 patients in four subgroups underwent a FDG PET/CT: a) 42 patients for solitary pulmonary nodules (SPNs) characterization with b) respective mediastinal lymph nodes (LNs), c) 65 patients for LN staging of head and neck cancer, and d) 36 cancer patients diagnosed with adrenal lesions. Receiver operating characteristics of SUVmax values were evaluated., Results: The SUVmax were statistically significantly greater in malignant than in benign lesions. For SPNs and mediastinal LNs, a SUVmax > 3.6 each resulted in a sensitivity of 81% and 87%, and a specificity of 94% and 89%. For cervical LNs and adrenal glands, a SUVmax > 2.2 each showed a sensitivity of 98% and 100%, and a specificity of 83% and 93%., Conclusion: A common SUVmax threshold did not exist in the four studied subgroups. The variable FDG uptake in SPNs and mediastinal LNs are associated with the high prevalence of inflammation/infection within the chest. Similar SUVmax thresholds however may exist for extrathoracic regions where the prevalence of inflammation/infection is low.

A 74-year-old man with 40-year history of smoking and known history of chronic lymphocytic leukemia and cutaneous T-cell lymphoma underwent FDG PET/CT examination for a recent diagnosis of squamous cell carcinoma diagnosed from right frontal crown and left posterior ear skin biopsy. PET images revealed multiple FDG-avid lesions in the head and neck, highly suspicious for nodal metastases. Reviewing CT portion of PET/CT examination revealed a hyperattenuating density in the posterior bladder wall. This lesion was not noticed initially due to the intense physiologic bladder uptake. On lowering the intensity, this lesion showed intense FDG avidity on the PET portion of the examination. Cytoscopic biopsy revealed low-grade papillary urothelial cell carcinoma.

Unlabelled: PET/CT fusion of anatomic and functional imaging modalities is in evolution, with rapid clinical dissemination. The imaged field of view (FOV) selected for whole-body PET/CT protocols is not standardized and varies by institution. Misuse of the term whole body, as well as the pressure to increase the number of daily studies by reducing scanning time, contributes to the lack of standardization. The purpose of this study was to evaluate variations in the FOV and arm positioning selected for whole-body PET/CT protocols at private, as well as academic, PET centers., Methods: Two hundred consecutive whole-body (18)F-FDG PET/CT studies were retrospectively reviewed for FOV: 50 studies from a private stationary site, 50 studies from 2 separate private mobile sites (25 consecutive studies from each), and 100 studies from a stationary university site: 50 before and 50 after implementation of a true whole-body protocol covering the top of the head through the bottom of the feet. Data were categorized into 5 different anatomic scan lengths: base of skull to upper thigh, base of skull to mid thigh, top of head to upper thigh, top of head to mid thigh, and true whole-body. Studies were further categorized into 2 patient arm positions: up and down., Results: The private stationary and mobile sites had only 2 categories of anatomic scan lengths identified: base of skull to mid thigh, and top of head to upper thigh. At the university site, before implementation of a true whole-body protocol, the 5 different anatomic scan lengths were identified; after implementation, only the true whole-body scan length was identified. Patients' arms in the private stationary sites were down 100% of the time. At the private mobile sites, patients' arms were up 72% of the time and down 28% of the time. At the university site, patients' arms were up 54% of the time and down 46% of the time. The same site, after implementation of a true whole-body protocol, had patients' arms up 58% of the time and down 42% of the time. Overall, patients' arms were up 46% of the time and down 54% of the time., Conclusion: The continued use of the term whole body is misleading because frequently it may not include the brain, skull, or significant portions of the upper and lower extremities. PET/CT anatomic scan length varied not only from one site to the next but also within individual sites. The Centers for Medicare and Medicaid Services have different current procedural terminology codes distinguishing between base of skull to upper thigh and true whole-body covering the top of the skull to the bottom of the feet, thus underscoring the need to standardize the terminology used in describing PET/CT scan length.

Purpose: The current study characterized pleural changes induced by talc pleurodesis (TP), based on serial positron emission tomography/computer-tomography (PET/CT) with F-18 fluorodeoxyglucose (FDG)., Materials and Methods: A total of 8 cancer patients who had both TP and PET/CT and no evidence of active pleural involvement after TP were retrospectively evaluated. Maximum standard uptake values, maximum Hounsfield units (HU), and thickness were followed over time., Results: The 8 patients had 25 PET/CT scans performed in an average of 22 months after TP. An increased FDG uptake was associated with an increase in pleural thickness within 5 months after TP, and both parameters showed statistical significance as compared with findings before TP. After 5 months of TP, the standard uptake value appeared to persist or increase further, and the pleural thickening stabilized. The formation of calcification was a slow process and might lag behind the changes in FDG metabolism and pleural thickness. The HU did not change significantly once pleural calcification had been formed., Conclusions: Knowledge of aforementioned pleural changes may help differentiate TP induced pleural inflammation from pleural malignancy and to avoid false-positive interpretation of FDG PET/CT exams.

Unlabelled: PET is a molecular imaging modality used to assess metabolic activity. Little is known about the physiologic uptake of radiopharmaceuticals such as (18)F-FDG in healthy subjects. This study was designed to identify and describe normal patterns of physiologic uptake of (18)F-FDG in healthy adult subjects and to examine the influence of low-level muscle activity during the (18)F-FDG uptake phase., Methods: Twenty healthy adults received an intravenous injection of (18)F-FDG and were subsequently scanned with a combined PET/CT scanner. The CT scan was used to accurately identify the location of (18)F-FDG uptake. Of the 20 subjects, 10 were randomly selected to perform a low-level muscle activity during the 1-h (18)F-FDG uptake phase. The PET/CT images were fused, and the location and intensity of metabolic activity were described for all subjects., Results: Muscle activity during the (18)F-FDG uptake phase affected the pattern of (18)F-FDG distribution on PET scans. In addition, the tissue uptake of (18)F-FDG, although variable, showed some consistency among tissue types., Conclusion: The data suggested that technologists should be aware of low-level muscle activity before and during uptake to avoid potential false-positive interpretations. The data also showed that there is some variability in the normal physiologic uptake of (18)F-FDG across subjects. Finally, the results suggested that (18)F-FDG uptake may be used for the evaluation of muscle activity.

Objective: An observation of increased (18)F-FDG uptake in the posterior ocular bulb led us to the hypothesis that increased posterior ocular bulb uptake is likely abnormal and may indicate intracranial lesions., Materials and Methods: Fifteen healthy volunteers and 35 patients with lung carcinoma-14 without brain metastasis and 21 with brain metastases-were retrospectively studied. The individuals underwent whole-body PET/CT including the brain with low-dose and unenhanced CT. Two nuclear medicine physicians visually analyzed the posterior ocular bulb uptake of both eyes. Standardized uptake values (SUVs) in the posterior ocular bulb were compared among the study groups. A radiologist reviewed brain MRI scans for abnormalities in the ocular bulbs and orbits., Results: Visual interpretation showed normal FDG uptake at the posterior ocular bulb in 14 of the 15 healthy volunteers and 12 of the 14 (86%) patients without brain metastasis. Seventeen of the 21 (81%) patients with brain metastases showed increased uptake in the posterior ocular bulb. Visual interpretation showed no statistically significant difference between the healthy volunteers and patients without brain metastasis (p = 0.671). However, there was a significant difference between the patients with brain metastases and healthy volunteers as well as patients without brain metastasis (both, p < 0.001). High interrater agreement (kappa = 0.83) was noted. Brain MRI showed no abnormalities at the posterior ocular bulb in all study subjects. SUV results were inaccurate because of the intense tracer activity in the posterior orbit nearby. A good correlation between visually increased posterior ocular bulb uptake and the presence of brain metastasis was present (Cramer's V = 0.61)., Conclusion: Visually increased FDG uptake along the posterior ocular bulb is an abnormal finding and may indicate intracranial structural abnormalities such as brain metastases.

Preoperative F-18 FDG PET/CT study in this 57-year-old woman showed an FDG avid lesion in the left upper lung without evidence of lymphadenopathy or distant metastasis. She underwent a left upper lobectomy in June 2005 revealing moderately poorly differentiated adenocarcinoma (pT3N0M0) and subsequent chemotherapy completed December 2005. Nine months later, a left parietal lobe metastatic lesion was surgically resected. A true whole body FDG PET/CT study in November 2006 for restaging demonstrated new FDG avid spinal cord foci, which were highly suspicious for spinal cord metastases; these lesions were confirmed by MRI. Clinically, the patient recently developed back pain without evidence of neurologic deficits.

Unlabelled: Obesity has reached epidemic proportions in the United States; hence, it is frequently encountered in patients undergoing (18)F-FDG PET studies. The purpose of the current study was to present a technologist's perspective on the prevalence of obesity and the challenges and solutions in imaging obese patients in our PET facility., Methods: From October 2002 to October 2003, whole-body (18)F-FDG PET was performed on 1,164 patients with a known or suspected malignancy. Images were acquired 45-60 min after (18)F-FDG injection (7.4 MBq [0.2 mCi]/kg, with a maximum of 925 MBq [25 mCi]) on a PET scanner using a 4-min emission and 3-min transmission time per bed position. A database was maintained of patient height and weight, and body mass index (BMI) was calculated. Patient obesity was classified as overweight (BMI > or = 25 kg/m(2)), obese (BMI > or = 30 kg/m(2)), or malignantly obese (BMI > or = 40 kg/m(2)). In addition, PET technologists recorded any problems and attempted solutions related to the patient weight., Results: BMI calculations showed that 528 patients (45.4%) were overweight or obese (322 men and 206 women; mean age, 55 y). Of those, 201 (38%) were overweight, 270 (51%) were obese, and 57 (11%) were malignantly obese. Problems encountered in these patients included difficult intravenous access (15%), difficult patient positioning (10%), patient motion (7%), an incomplete study (emission only) (1%), and potentially higher radiation exposure to the technologist because of extra time spent near the patient. Attempted solutions included adjusting the schedule to allow more time per patient, adjusting the dose based on body weight, using varied positioning techniques, dividing the study to allow a respite between different image combinations, and dividing time spent with obese patients among the technologists involved., Conclusion: Excessive body weight and related problems have commonly been encountered in our PET facility. (18)F-FDG PET studies of obese patients represent an ongoing challenge, which requires patient-tailored solutions to avoid compromising image quality and risking higher radiation exposure to the technologists.

Unlabelled: Recently, the use of 18F-FDG PET has progressed rapidly as a standard diagnostic imaging tool in many types of cancer. The purpose of this study was to evaluate the patterns and prevalence of muscle uptake as a result of muscle activity shortly before the 18F-FDG injection or during the uptake phase., Methods: From October 2002 to October 2003, whole-body 18F-FDG PET scans (4-min emission and 3-min transmission per bed position) were performed on 1,164 patients with known or suspected malignancy. Images were acquired on a dedicated PET scanner 45-60 min after an intravenous injection of a weight-adjusted dose of 7.4 MBq/kg (0.2 mCi/kg) with a maximum of 925 MBq (25 mCi) 18F-FDG. A log of any nonphysiologic muscle activity during the uptake phase or reported excessive muscle activity the day before scanning was kept by the technologists. In addition, PET scans were reviewed retrospectively to evaluate any undesirably increased muscle uptake., Results: A total of 146 of 1,164 patients (12.5%) had excessively increased muscle uptake detected on the PET scan that corresponded to the technologists' notes of muscle activity during the uptake phase or before 18F-FDG injection. Encountered patterns of muscle uptake due to muscle activity included uptake in neck, secondary to neck strain from being on a stretcher; masseter, secondary to chewing gum; vocal cords, secondary to speaking; chest wall, secondary to labored breathing; forearms and hands, secondary to reading; and lower extremities, secondary to nervous tapping of the feet., Conclusion: Undesirably increased physiologic muscle uptake is frequently encountered on 18F-FDG PET scans. In this study, 12.5% of patients were affected. It is prudent to instruct the patient to avoid any excessive physical activity at least 48 h before injection as well as to not exert muscle activity during the uptake phase. Furthermore, a record should be kept by the technologist of any observed excessive muscle activity during the uptake phase and reported to the reading physician-thus, eliminating a potential source of false-positive findings on interpreting PET scans.

A 48-year-old male smoker presented with a chief complaint of persistent cough for three months. A CT scan revealed only a large right paratracheal mass. The plan was to obtain histological confirmation of suspected lung cancer via bronchoscopy and mediastinoscopy. A whole body 18F-FDG (2-deoxy-2-[18F]fluoro-D-glucose) PET Scan was ordered for staging and localization of the most accessible biopsy site. There was a large, intense hypermetabolic focus corresponding to the paratracheal lesion seen on CT, as well as a lesion in the right adrenal gland. There was also a superficial, subcutaneous hypermetabolic lesion in the mid-back. The subcutaneous lesion, which previously had not been noted, was biopsied and proved to be metastatic adenocarcinoma consistent with the lung primary. This case illustrates the clinical utility of reporting soft tissue abnormalities, which may provide an alternative, more readily accessible location for biopsy that is both safer and less expensive than bronchoscopy or mediastinoscopy.

Purpose: To retrospectively evaluate the distribution of fluorine 18 fluorodeoxyglucose (FDG) in the head and neck region with combined positron emission tomography-computed tomography (PET/CT) in patients with no known abnormality in this region., Materials and Methods: The institutional review board allowed a retrospective review of PET/CT images obtained in 78 patients with non-head and neck cancer and waived the requirement for informed consent. The accumulation of FDG in 11 normal head and neck structures was visually and quantitatively assessed retrospectively. Positive rate percentage (PRP) was defined as the sum of the percentages of patients with grade 2 and grade 3 tracer uptake intensity. Standardized uptake values (SUVs) were calculated for quantitative analysis. Mean SUVs were compared between the male and female patients by using the unpaired t test, and the correlation between FDG uptake and patient age was assessed by using the Pearson correlation coefficient test., Results: Intense tracer uptake was usually seen in the palatine tonsils (PRP, 98%; mean SUV, 3.48), soft palate (PRP, 96%; mean SUV, 3.13), and lingual tonsils (PRP, 96%; mean SUV, 3.11). In the inferior concha (PRP, 4%; mean SUV, 1.56), thyroid gland (PRP, 3%; mean SUV, 1.31), and tongue (PRP, 1%; mean SUV, 1.39), uptake was typically minimal. FDG accumulation was variable in the sublingual glands (PRP, 72%; mean SUV, 2.93), spinal cord (PRP, 64%; mean SUV, 2.12), submandibular glands (PRP, 53%; mean SUV, 2.11), parotid glands (PRP, 51%; mean SUV, 1.90), and vocal cords (PRP, 19%; mean SUV, 1.77). The mean normal-tissue SUV in the soft palate was higher in male than in female patients (P <.01). A negative correlation between age and physiologic FDG uptake was seen in the palatine tonsils (r=-0.51, P <.001) and sublingual glands (r=-0.70, P <.001)., Conclusion: Intense FDG uptake was usually observed in the palatine tonsils, lingual tonsils, and soft palate, whereas uptake in the major salivary glands was variable.

This article aims to increase awareness about the utility of (18)F -FDG-PET/CT in the evaluation of cranial nerve (CN) pathology. We discuss the clinical implication of detecting perineural tumor spread, emphasize the primary and secondary (18)F -FDG-PET/CT findings of CN pathology, and illustrate the individual (18)F -FDG-PET/CT CN anatomy and pathology of 11 of the 12 CNs.

Objective: The current guidelines for 2-deoxy-2-[18F]fluoro-d-glucose PET/CT scanning do not address potential inaccuracies that may arise due to patients with renal failure. We report a retrospective analysis of standard uptake values (SUVs) in patients with and without renal failure in order to warrant a protocol adjustment. Methods: Patients were matched based on age, gender, and BMI all of which are potential effectors on observed SUV. Thirty patients were selected with clinically diagnosed renal failure, of which 12 were on dialysis. All 30 patients had age, gender, and BMI control matches. Blood urea nitrogen and creatinine levels were measured within 1 month of the scan to assess renal failure. PET/CT scans for both the renal failure patients and controls were performed 60 min after FDG injection. SUVs were measured by placing circular regions of interest in the right hepatic lobe (LSUV) and left psoas muscle (PSUV). Results: For the 30 renal failure patients, the mean LSUV was 2.77 (SD = 0.57) and PSUV was 1.43 (SD = 0.30) while the controls had mean LSUV 2.74 (SD = 0.50) and PSUV 1.42 (SD = 0.37). The SUVs from both the liver and psoas muscle were not significantly different between the renal failure patients and the normal controls with p values >0.05. In addition, dialysis and gender also had no effect on SUVs. Conclusion: Our data suggest that renal failure patients do not require an adjustment in protocol and the standard protocol times should remain. [ABSTRACT FROM AUTHOR]