Benign Uptake Research Articles

Squamous Cell Carcinoma of the Palatine Tonsils: FDG Standardized Uptake Value Ratio as a Biomarker to Differentiate Tonsillar Carcinoma from Physiologic Uptake

To quantify fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake in the palatine tonsils to identify a sensitive and specific metric for distinguishing physiologic asymmetric uptake from squamous cell carcinoma (SCC). This HIPAA-compliant retrospective study was approved by institutional review board. Informed consent requirements were waived. Twenty-six patients (seven female, 19 male; mean age, 53.46 years + or - 10.45 [standard deviation]) with tonsillar SCC were included. Twenty-six patients (seven female, 19 male; mean age, 61.77 years + or - 10.12) with head and neck carcinomas not involving the tonsils were included as control subjects. Tonsil standardized uptake values (SUVs) were measured bilaterally in each group. Independent-samples t test was used to compare mean SUVs, and Pearson correlation was used to evaluate association of FDG uptake between tonsils within control subjects. The mean maximum SUV (SUV(max)) of tonsil tumors was 9.36 + or - 4.54, which was significantly higher than that of contralateral cancer-free tonsils (2.54 + or - 0.88; P < .0001) and tonsils in control subjects (2.98 + or - 1.08; P < .0001). In patients with tonsillar cancer, the mean difference in SUV(max) between tonsils was 10.43 + or - 7.07, which was significantly greater than that in control subjects (0.62 + or - 0.54; P < .0001). The mean SUV(max) ratio between tonsils in patients with carcinoma was 3.79 + or - 1.69, which was threefold higher than in control subjects (1.18 + or - 0.13; P < .0001). For receiver operating characteristic analysis using SUV(max) ratio to differentiate benign uptake from SCC, the area under the curve was 1.00 (95% confidence interval: 1.00, 1.00). A cutoff ratio of 1.48 had 100% sensitivity and specificity. The SUV(max) ratio represents an accurate imaging biomarker for differentiating tonsillar SCC from physiologic (18)F-FDG uptake.

Hot tongue on FDG PET scan in a patient of Hodgkin′s lymphoma undergoing antipsychotic treatment

Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography (F-18 FDG PET-CT) is the modality of choice for the diagnosis, staging, and restaging of many malignancies. The importance of eliminating false positives cannot be underestimated because they can dramatically alter the clinical course. We present a case of benign uptake in the tongue secondary to tardive dyskinesia in a 53-year-old woman referred for therapy response evaluation of Hodgkin’s lymphoma who was concurrently receiving oral antipsychotic therapy. This case emphasizes the importance of detailed clinical history and examination when concluding definite diagnosis.

Orthopedic surgery-related benign uptake on FDG-PET: case examples and pitfalls

Orthopedic surgical procedures often create some special postoperative complications, which may demonstrate abnormally increased or focal uptake for an extended period of time on FDG PET-CT images. The distinction of normal from pathologic, benign from malignant uptake is very important to minimize the number of false positive results. To date, very little data have been published regarding surgical-related benign musculoskeletal uptake on PET-CT imaging. In this paper, we present to the readers some case examples of FDG PET-CT imaging for postoperative fracture, infection or osteomyelitis, metallic implants, aggressive bone edge, heterotopic ossification, granuloma and neuroma. We also discuss potential pitfalls to recognize these orthopedic surgery-related complications and identify benign nature of increased FDG uptake. In all cases, the patient's medical and surgical history would be of paramount importance to the radiologists/nuclear medicine physicians who interprets the scan. It is also crucial to carefully correlate FDG uptake with the anatomy on the co-registered CT images in all transaxial, coronal and sagittal views in order to identify the location and pattern of uptake.

Chilaiditi Sign Appearing as a Liver Lesion on FDG PET

Abstract: A clear understanding of normal physiological distribution of the radiopharmaceutical, commonly encountered normal variants, and benign pathologic uptake is important to avoid mistaken diagnosis on an F-18 FDG PET scan. The distribution of FDG in the bowel is variable and may occasionally lead to diagnostic pitfalls. Chilaiditi sign is a well-known anatomic variant and describes the interposition of bowel between the liver and diaphragm. The authors present a case where an apparent abnormality in the liver on an FDG PET only study was proven to be due to bowel activity related to Chilaiditi sign on CT correlation.

Diagnostic accuracy of 18f-2-deoxy-fluoro-d-glucose positron emission tomography for pn1 lymph nodes in patients with lung cancer

Nodal status has been reported to be one of the most important factors affecting survival in patients with lung cancer. For determining treatment strategy, accurate evaluation of nodal status is expected. To evaluate the accuracy of (18)F-2-deoxy-fluoro-D-glucose (FDG) positron emission tomography (PET) for diagnosing nodal status in lung cancer patients with pathologically proven N1 (pN1) lymph node metastases, in comparison with that of computed tomography (CT). Nineteen pN1 patients with primary lung cancer undergoing preoperative CT and FDG-PET were investigated. The diagnosis was confirmed by surgery in all patients. Lymph nodes were considered to be positive when uptake higher than the surrounding mediastinum level was visually observed. Radiological and pathological correlation was investigated, and the association between FDG uptake and the size of metastatic nodes was evaluated. Of the 19 pN1 patients, nodal stage determined by FDG-PET was cN0 in eight, cN1 in four, cN2 in six, and cN3 in one. Thus, FDG-PET provided correct N-staging in 21%, under-staging in 42%, and over-staging in 37%. FDG-PET could not depict pN1 lymph node in six (32%) of 19 patients. In two patients (11%), mild symmetrical hilar and mediastinal accumulation was found and considered as benign physiological uptake. In six patients (32%), the ipsilateral mediastinal uptake was depicted and diagnosed as cN2. One patient was diagnosed as cN3 because of FDG accumulation at the supraclavicular fossa. On CT, nodal staging was cN0 in nine, cN1 in six, and cN2 in four. CT staging was therefore correct in 32%, underestimated in 47%, and overestimated in 21%. The diagnostic accuracy of FDG-PET (21%) was low and similar to that of CT (32%); under- and over-diagnosis were found in similar proportions. The limitation of FDG-PET should be recognized when nodal staging might alter the therapeutic strategy in patients with primary lung cancer.

Incremental Value of 131I SPECT/CT in the Management of Patients with Differentiated Thyroid Carcinoma

(131)I whole-body scintigraphy (WBS) is a highly sensitive method for the detection of differentiated thyroid tumors and metastases. However, a lack of anatomic landmarks and the physiologic accumulation of the tracer complicate interpretation of the images. This prospective study was designed to evaluate the incremental value of (131)I SPECT/CT over planar WBS in the management of patients with differentiated thyroid carcinoma (DTC). Planar imaging was performed on 66 consecutive DTC patients who were considered to have locally advanced or metastatic disease after total or nearly total thyroidectomy. SPECT/CT was added for patients whose planar findings were inconclusive. The planar images were interpreted by 2 experienced nuclear medicine physicians. Interpretation of the SPECT/CT images was a consensus opinion of one of the nuclear medicine physicians and an experienced radiologist. Fusion images were considered to improve image interpretation when they better localized sites of increased (131)I uptake. The final diagnosis was verified by pathologic findings, other imaging modalities, and clinical follow-up. Both site-based and patient-based analyses were performed, and the impact of SPECT/CT results on therapeutic strategy was assessed. A total of 232 foci were observed by (131)I WBS, including 33.2% of foci localized in the thyroid bed, 62.1% due to malignant lesions, and 4.7% caused by nonthyroidal physiologic or benign uptake or a contaminant. Overall, 37 SPECT/CT studies were performed on 23 patients, whose planar images showed 81 inconclusive lesions. Precise localization and characterization of (131)I-avid foci were achieved through (131)I SPECT/CT in 69 (85.2%) and 67 (82.7%) of the 81 foci, respectively. Fusion images were considered to be of benefit in 17 (73.9%) of 23 patients. The therapeutic strategy was changed in 8 (47.1%) of 17 patients. Uncommon metastatic lesions were found in 9 (13.6%) of 66 patients with regard to SPECT/CT fusion images. Fusion of SPECT and CT images was of incremental value over WBS in increasing diagnostic accuracy, reducing pitfalls, and modifying therapeutic strategies in 73.9% of DTC patients. As SPECT/CT techniques emerge, (131)I SPECT/CT may demonstrate higher value than WBS in the management of DTC.

Benign Tongue FDG Uptake in a Patient With Tardive Dyskinesia

Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography (F-18 FDG PET-CT) is the modality of choice for diagnosis, staging, and restaging of many malignancies. The importance of eliminating false positives cannot be underestimated because they can dramatically alter the clinical course. We present a case of benign uptake in the tongue secondary to tardive dyskinesia in a 62-year-old woman referred for staging of ductal carcinoma of the breast who was concurrently receiving oral therapy for schizoaffective disorder. This case emphasizes the importance of direct clinical interview and adequate history taking in the formulation of an appropriate diagnosis.

Benign Nonphysiologic Lesions with Increased 18F-FDG Uptake on PET/CT: Characterization and Incidence

The objective of our study was to characterize benign lesions showing increased 18F-FDG uptake and to determine their incidence on whole-body FDG PET/CT performed in oncologic patients. In addition, the performance of PET alone and PET/CT in characterizing lesions as benign was compared. A retrospective review of 1,134 consecutive reports of PET/CT studies performed in patients with proven or suspected malignancy over a 6-month period yielded 289 patients with 313 lesions that showed increased FDG uptake but were suspected to be benign (nonphysiologic) or indeterminate. Lesions were subjectively categorized on the basis of the intensity of FDG uptake (mild, moderate, or marked) as compared with background activity. For each lesion, a decision was made as to whether a benign diagnosis could be obtained by the CT part of the study, the PET pattern, or clinical correlation, or whether histologic sampling was necessary. The performance of PET alone and PET/CT for characterizing lesions as benign was compared. Two hundred twenty-nine of the lesions were assessed further: 210 were benign and 19, malignant. The final diagnosis was determined by pathology (n = 67), PET/CT follow-up (n = 58), correlative imaging (n = 59), clinical correlation (n = 32), or typical benign pattern on PET/CT (n = 13). The causes for benign uptake of FDG were inflammatory processes (n = 154, 73.3%), benign tumors (n = 23, 11%), hematoma or seroma (n = 17, 8.1%), fracture (n = 7, 3.3%), fat necrosis (n = 3, 1.4%), and others (n = 6, 2.9%). For lesions with moderate or marked uptake of FDG (n = 117, 55.7%), a benign diagnosis could have been suggested on either PET or CT (e.g., a "hot" osteophyte) in 33 lesions (28.2%), on CT alone (e.g., peritoneal fat necrosis) in 38 lesions (32.5%), on PET alone (e.g., sialadenitis) in 10 lesions (8.5%), or by clinical correlation (e.g., dental abscess) in four lesions (3.4%). A benign diagnosis could not be established without histology (e.g., colonic polyp) in 32 lesions (27.4%). The performance of PET/CT was superior to that of PET alone in characterizing lesions as benign (p < 0.001). Benign lesions with increased FDG uptake are found in more than 25% of the PET/CT studies performed in patients with proven or suspected malignancy, with inflammation being the most common cause. Lesion characterization on the CT portion of the PET/CT study increases the specificity of PET/CT reporting, especially for lesions with moderate or marked FDG uptake.

The additional value of PET/CT over PET in FDG imaging of oesophageal cancer

The aim of this study was to assess the value of combined PET/CT compared with PET reviewed side-by-side with CT, in patients with oesophageal cancer, before and after surgery. Forty-one FDG PET/CT studies were performed in 32 patients with oesophageal cancer, before surgery (n = 18) or during follow-up after resection of the primary tumour (n = 23). One hundred and fifteen sites suspicious for malignancy were evaluated. PET/CT was prospectively compared with PET reviewed side-by-side with CT, for detection, accurate localisation and characterisation of malignant sites. PET/CT performance in different anatomical regions was compared before and after surgery. The impact of fused data on patient management was retrospectively assessed. PET/CT had an incremental value over PET for interpretation of 25 of 115 sites (22%), changing the initial characterisation of ten sites to either malignant (n = 1) or benign (n = 9), and defining the precise anatomical location of 15 sites. PET/CT provided better specificity and accuracy than PET for detecting sites of oesophageal cancer (81% and 90% vs 59% and 83% respectively, p < 0.01). Fusion was of special value for interpretation of cervical and abdomino-pelvic sites, for disease assessment in loco-regional lymph nodes before surgery and in regions of postoperative anatomical distortion. PET/CT had an impact on the further management of four patients (10%), by detecting nodal metastases that warranted disease upstaging (n = 2) and by excluding disease in sites of benign uptake after surgery (n = 2). PET/CT improves the accuracy of FDG imaging in oesophageal cancer and provides data of diagnostic and therapeutic significance for further patient management.

Single-photon emission computed tomography quantitation of gallium citrate uptake for the differentiation of lymphoma from benign hilar uptake.

To assess the role of quantitative gallium citrate (Ga 67) single-photon emission computed tomography (SPECT) in differentiating lymphoma from benign hilar uptake, concentrations of Ga 67 in 29 sites of documented lymphoma and in 75 benign lesions were compared. One hundred seven thoracic Ga 67 SPECT studies obtained in 101 consecutive lymphoma patients were reviewed. Fifty-nine studies detected Ga 67 uptake in the hilar and or mediastinal regions. Forty-eight studies showed no such abnormality. The concentration of Ga 67 in the thoracic lesions was measured using a quantitative SPECT technique and its nature was determined by correlation with computed tomographic (CT) scans and follow-up evaluation of the sites. In 20 of 59 abnormal studies (34%), there was lymphoma in the hilar and or mediastinal regions. In the remaining 39 abnormal studies (66%), Ga 67 uptake was benign. There were 29 sites of lymphoma and 75 benign lesions. The concentration of Ga 67 in lymphoma was significantly higher than in benign hilar uptake (13.2 +/- 5.4 %ID/mL x 10(-3) v 5.6 +/- 1.5 % injected dose (ID)/mL x 10(-3); P < .001). A concentration value of 8.3 %ID/mL x 10(-3) was found to best separate lymphoma and benign uptake, with a sensitivity of 90%, a specificity of 93%, a positive predictive value of 84%, and a negative predictive value of 96%. Lymphoma and benign hilar uptake differ significantly in their concentration of Ga 67. The present study shows that quantitative Ga-67 SPECT reliably differentiates lymphoma and benign uptake.

High frequency of benign mediastinal uptake of gallium-67 after completion of chemotherapy in children with high-grade non-Hodgkin's lymphoma.

We observed increased gallium-67 uptake in the mediastinum after completion of chemotherapy in 10 of 62 patients with non-Hodgkin's lymphoma. All 10 were under 15 years of age, yielding a frequency of 43% in this age group. The interval between cessation of chemotherapy and the development of increased gallium-67 uptake ranged from 1 to 8 months, and the abnormality persisted for 2 to 59 months. Serial chest x-rays were performed in all patients, and four of the 10 had transient widening of the mediastinum that remained within normal limits for the children's ages. Three patients had chest computed tomographic (CT) scans at the time of increased gallium-67 uptake, and one of the three had serial scans that showed a mediastinal mass consistent with thymic enlargement. All of the patients were asymptomatic and none were biopsied. All 10 remained well, with a mean follow-up of 52.5 months. The phenomenon we describe is probably due to "rebound" thymic hyperplasia, which is a benign and transient condition. We conclude that abnormal mediastinal gallium-67 uptake after completion of chemotherapy is likely to be benign and transient if the patients are young, have small non-cleaved-cell histology, are without other evidence of lymphoma recurrence, and do not have initial mediastinal involvement. Progressive widening of the mediastinum on chest x-ray is cause for suspicion and requires further evaluation. Serum lactate dehydrogenase (LDH) levels may not be helpful in differentiating a benign from a malignant process.

A benign uptake of 99mTc-polyphosphate after radical mastectomy.

Increased uptake of 99mTc-pp was observed in 10 patients after radical mastectomy. This unilateral localized increased activity was centered at the surgical site. The lack of tissue absorption of the low energy gamma photons of 99mTc-pp due to the absence of chest wall tissue accounted for this activity. Studies of normal patients and patients with simple mastectomies did not show this finding. A routine breast examination is recommended prior to interpreting 99mTc-pp bone scans of patients with breast cancer.

Belated Diagnosis of Hashimoto's Disease

<b>978</b> <h3><b>Objectives:</b></h3> 1. To recognize patterns of uptake in different ganglia which may mimic lymph node metastases in different anatomic locations 2. To understand the role of CT characterization and localization in the differentiation of benign uptake in ganglia versus metastatic lymph nodes. 3. How to interpret these findings and direct further evaluation or recommendation if needed. <b>Abstract:</b> Several recent studies revealed accurate staging of primary prostate cancer (PC) and restaging after biochemical recurrence with ⁶⁸Ga -PSMA PET/CT. However, ⁶⁸Ga -PSMA uptake is not completely specific to PC. Recent study showed relatively high PSMA uptake in coeliac ganglia in most patients which may mimic lymph node metastases in this area in PC patients undergoing ⁶⁸Ga -PSMA PET/CT examination for staging or restaging¹. We will demonstrate in a large collection of cases varieties of findings with different patterns of PSMA uptake which would include unilateral and bilateral uptake, mild and moderate uptake, focal and diffuse uptake, isolated ganglion uptake and multiple ganglia uptake in same patient. Also, correct and careful of interpretation of the CT scan as part of the ⁶⁸Ga-PSMA PET/CT examination is of special importance in differentiating PSMA uptake in a ganglia versus in lymph nodes. Associated CT findings and characterization of ganglia in the ⁶⁸Ga-PSMA PET/CT would be demonstrated at different location including stellate ganglia in the cervicothoracic region, coeliac and superior mesenteric in the abdomen and inferior mesenteric in the pelvic region. We will also show the appearance of some of these findings by other imaging modalities for further characterization. Reading physician should be aware of the frequently encountered physiologic uptake of 68Ga-labelled PSMA ligand in different ganglia in order to avoid false positive interpretation.