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IgG4-related disease (IgG4-RD) is a rare and often misdiagnosed disorder with limited literature that highlights the different neurological presentations of this treatable disease. The diagnosis of IgG4-RD could be challenging, while imaging is fundamental for the diagnosis, biopsy is considered the gold standard. Most cases respond well to steroids and immunosuppressive therapy. This is a case series study that illustrates the varied neurological presentations of IgG4-RD through three different patients that were followed at the Montreal Neurological Institute. This paper takes you through the diagnostic strategy that we followed to accurately diagnose and treat those patients.

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OBJECTIVE. The paradigm of theranostics is based on tailoring therapy for the purpose of optimizing outcomes. This principle is being applied to radioactive iodine therapy. Consequently, thyroid cancer therapy protocols are evolving. The purpose of this article is to promote a modern approach to radioiodine therapy. CONCLUSION. This article highlights guidelines and position statements, summarizes the prognostication systems of thyroid cancer, and reviews which prescribed activities of 131I.

A 65-year-old male patient with a one year history of liver transplantation was referred for an 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) to rule out post transplant lymphoproliferative disease. Multiple foci of intense abnormal 18F-FDG uptake were seen in the transplanted liver which were concerning for malignancy. Explantation of the liver approximately 1 month following the PET/CT revealed multiple inflammatory and ischemic changes including large bile duct necrosis, acute cholangitis, bile duct obstruction changes and periportal fibrosis, with no evidence of malignancy. We present the 18F-FDG PET/CT image findings of this case.

Objective The purpose of the current study is to examine the incidence and clinical significance of unexpected focal uptake of 18F-fluorodeoxyglucose (18F-FDG) on positron emission tomography/computed tomography (PET/CT) in the thyroid gland of oncology patients, the maximum standardized uptake value (SUVmax) of benign and malignant thyroid incidentalomas in these patients, and review the literature. Methods Seven thousand two hundred fifty-two 18F-FDG PET/CT studies performed over four years, were retrospectively reviewed. Studies with incidental focal 18F-FDG uptake in the thyroid gland were further analyzed. Results Incidental focal thyroid 18F-FDG uptake was identified in 157 of 7252 patients (2.2%). Sufficient follow-up data (≥12 months) were available in 128 patients, of whom 57 (45%) had a biopsy performed and 71 had clinical follow-up. Malignancy was diagnosed in 14 of 128 patients (10.9%). There was a statistically significant difference between the median SUVmax of benign thyroid incidentalomas (SUVmax 4.8) vs malignant (SUVmax 6.3), but the wide range of overlap between the two groups yielded no clinically useful SUVmax threshold value to determine malignancy. Conclusion 18F-FDG positive focal thyroid incidentalomas occurred in 2.2% of oncologic PET/CT scans, and were malignant in 10.9% of 128 patients. This is the lowest reported malignancy rate in a North American study to date, and significantly lower than the average malignancy rate (35%) reported in the literature. Invasive biopsy of all 18F-FDG positive thyroid incidentalomas, as recommended by some studies, is unwarranted and further research to determine optimal management is needed. There was no clinically useful SUVmax cut-off value to determine malignancy and PET/CT may not be a useful imaging modality to follow these patients conservatively.

The aim of this study was to evaluate the clinical significance of incidental focal uptake ofA retrospective review of 3122 consecutive male patients who underwentIncidentalAmaç: Bu çalışmanın amacı kanser hastalarının prostat bezinde pozitron emisyon tomografisi/bilgisayarlı tomografide (PET/BT) insidental olarak saptanan fokal 18F-fluorodeoksiglukoz (18F-FDG) tutulumunun klinik önemini değerlendirmektir. Yöntem: Dört yıllık bir dönemde onkolojik nedenlerle 18F-FDG-PET/BT uygulanmış 3122 ardışık erkek hasta retrospektif olarak incelendi. Prostat bezinde insidental 18F-FDG tutulumu saptanan hastalar detaylı olarak değerlendirildi. Bulgular: Prostat bezinde insidental 18F-FDG tutulumu 65/3,122 erkekte (%2,1) saptandı. Yeterli takip verisi (≥12 ay) olan 53 hasta mevcuttu, bunların 11’ine biyopsi uygulanmış 42’si klinik ve radyolojik olarak takip edilmişti. Elli üç hastanın dördünde malignite histolojik olarak saptanmıştı (%7,5). Benign ve malign prostat lezyonlarında 18F-FDG tutulum değerleri açısından istatistik olarak anlamlı fark yoktu [maksimum standart uptake değeri (SUVmaks) benign: SUVmaks 7,3, malign: SUVmaks 7,2, p=0,95]. Benign ve malign grup hastalarda serum prostat spesifik antijen (PSA) değerleri arasında istatistiksel olarak anlamlı fark vardı (benign grup n=24, PSA=2,7 ng/mL, malign grup n=4, PSA=9,2 ng/mL, p0,001). SUVmax ve Gleason skoru arasında direkt korelasyon mevcuttu. Sonuç: Onkolojik PET/BT görüntülemelerinin %2,1’inde 18F-FDG pozitif prostat bezi insidentaloması saptandı ve bunların %7,5’i malign idi. SUVmaks, benign ve malign insidental prostat lezyonlarını ayırt etmede yararlı değildi. PET/BT’de 18F-FDG tutulumu olan prostat bezi insidentaloması varlığında serum PSA değerinin bakılması önerilmeli ve eğer PSA yüksek ise ileri tetkik gerekliliği akılda tutulmalıdır.

Low grade lymphoma may transform into a more aggressive lymphoma and this transformation is usually associated with a poor outcome. A 65year old man presented with two metabolically active splenic lesions on a staging [18F] fluoro-2-deoxy-d-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT). Histologic evaluation post splenectomy confirmed the presence of two clonally related lymphomas: a follicular lymphoma (FL) and a diffuse large B-cell lymphoma (DLBCL). Molecular genetic studies confirmed that the DLBCL lesions arose from a pre-existing FL. We present the 18F-FDG PET/CT imaging characteristics of both lymphoma types which were simultaneously present in the spleen.

A 67-year-old female patient with no prior history of benign thyroid disease was diagnosed with primary thyroid lymphoma and was staged with18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT). She was treated with chemotherapy and external beam radiation therapy, and a follow-up PET/CT showed significant reduction in the size of the thyroid lymphoma with persistent intense 18F-FDG uptake, which was interpreted as partial response to therapy. However, two subsequent PET/CT studies showed no change in the persistent intense 18F-FDG uptake in the thyroid and a biopsy confirmed the presence of thyroiditis with no evidence of residual lymphoma. Follow-up PET/CTs performed over the subsequent three years showed stable intensely 18F-FDG avid thyroiditis with no evidence of lymphoma recurrence. We present the imaging characteristics of a long term radiation treatment induced thyroiditis mimicking 18F-FDG avid residual disease on PET/CT.

A 65-year-old male patient with a one year history of liver transplantation was referred for an 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) to rule out post transplant lymphoproliferative disease. Multiple foci of intense abnormal 18F-FDG uptake were seen in the transplanted liver which were concerning for malignancy. Explantation of the liver approximately 1 month following the PET/CT revealed multiple inflammatory and ischemic changes including large bile duct necrosis, acute cholangitis, bile duct obstruction changes and periportal fibrosis, with no evidence of malignancy. We present the 18F-FDG PET/CT image findings of this case.

The aim of this study was to evaluate the frequency and clinical significance of incidental focal uptake of (18)F-fluorodeoxyglucose (FDG) on positron emission tomography/computed tomography (PET/CT) in the parotid glands of cancer patients. A retrospective review of 7,252 oncologic PET/CT studies was done. FDG positive parotid incidentalomas occurred in 0.4% of PET/CT scans, of which only 4% were malignant. PET/CT was unable to differentiate benign from malignant parotid lesions based on SUVmax alone. (18)F-FDG positive parotid incidentalomas can be managed conservatively, however patients with a prior history of lymphoma had a much higher risk of parotid malignancy and require further investigation.

Objective: The purpose of the current study is to examine the incidence and clinical significance of unexpected focal uptake of 18F-fluorodeoxyglucose (18F-FDG) on positron emission tomography/computed tomography (PET/CT) in the thyroid gland of oncology patients, the maximum standardized uptake value (SUVmax) of benign and malignant thyroid incidentalomas in these patients, and review the literature. Methods: Seven thousand two hundred fifty-two 18F-FDG PET/CT studies performed over four years, were retrospectively reviewed. Studies with incidental focal 18F-FDG uptake in the thyroid gland were further analyzed. Results: Incidental focal thyroid 18F-FDG uptake was identified in 157 of 7252 patients (2.2%). Sufficient follow-up data (≥12 months) were available in 128 patients, of whom 57 (45%) had a biopsy performed and 71 had clinical follow-up. Malignancy was diagnosed in 14 of 128 patients (10.9%). There was a statistically significant difference between the median SUVmax of benign thyroid incidentalomas (SUVmax 4.8) vs malignant (SUVmax 6.3), but the wide range of overlap between the two groups yielded no clinically useful SUVmax threshold value to determine malignancy. Conclusion: 18F-FDG positive focal thyroid incidentalomas occurred in 2.2% of oncologic PET/CT scans, and were malignant in 10.9% of 128 patients. This is the lowest reported malignancy rate in a North American study to date, and significantly lower than the average malignancy rate (35%) reported in the literature. Invasive biopsy of all 18F-FDG positive thyroid incidentalomas, as recommended by some studies, is unwarranted and further research to determine optimal management is needed. There was no clinically useful SUVmax cut-off value to determine malignancy and PET/CT may not be a useful imaging modality to follow these patients conservatively.

Systemic lupus erythematosus (SLE) is associated with a variety of inflammatory processes that can affect the lymph nodes, brain, kidneys, and spleen. We present two patients with SLE in whom SLE-associated conditions complicated interpretation of 18F-fluoro-2-deoxy-d-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) imaging of the lymph nodes and the spleen. The imaging findings mimicked lymphoma, but histopathological evaluation showed benign processes including reactive follicular hyperplasia in the lymph nodes, Kikuchi-Fujimoto disease in perisplenic lymph nodes, and inflammatory changes and lymphoid hyperplasia in the spleen.

ImportanceAnti-N-methyl-d-aspartate receptor (anti-NMDAR) autoimmune encephalitis is an increasingly recognized cause of limbic encephalitis (LE). Prolonged LE and limbic status epilepticus (LSE) share many features. The ability to distinguish between the two is crucial in directing appropriate therapy because of the potential iatrogenesis associated with immunosuppression and anesthetic-induced coma.ObservationsA 34-year-old woman with recurrent LE developed behavioral changes, global aphasia, and repetitive focal and generalized tonic–clonic seizures. Because asymmetric rhythmic delta patterns recurred on electroencephalography (EEG) despite treatment with nonsedating antiepileptic drugs followed by anesthetic-induced coma, an investigation to distinguish LSE from LE was undertaken. Implanted limbic/temporal lobe depth electrodes revealed no epileptiform activity. Brain single-photon emission computerized tomography (SPECT) showed no hyperperfusion, and brain fluorodeoxyglucose-positron emission tomography (FDG-PET) showed hypermetabolism in the left frontal, temporal, and parietal cortices. Anti-N-methyl-d-aspartate receptor autoimmune encephalitis was diagnosed based detection of anti-NMDAR antibody in the cerebrospinal fluid (CSF). With chronic immunosuppression, the resolution of brain FDG-PET abnormalities paralleled clinical improvement.Conclusions and relevanceThis case of anti-NMDAR autoimmune encephalitis illustrates the challenges of distinguishing prolonged LE from LSE. We discuss the parallels between these two conditions and propose a management paradigm to optimize evaluation and treatment.

A 67 year old woman with a 10 year history of rheumatoid arthritis (RA) treated with methotrexate and prednisone, presented with a 2 year history of worsening multiple cutaneous plaques of variable appearance. Two distinct skin lesions were biopsied to reveal a composite cutaneous lymphoma, possibly caused by long term methotrexate therapy. An [18F] fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) was performed to stage the malignancy, and was later repeated to evaluate response to chemotherapy, which guided subsequent management. We present the PET/CT imaging findings of this very rare iatrogenic (methotrexate induced) immunodeficiency-associated lymphoproliferative disorder.

The aim of this pictorial essay was to highlight the usefulness of fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in evaluating incidental infection or inflammation in cancer patients, related to surgical management. A retrospective review of 10,985 consecutive oncologic PET/CTs was done, and nine cases with suspected FDG positive infectious or inflammatory processes were selected for further review. PET/CT helped identify infections and inflammatory processes related to surgical management of cancer patients, define the extent of infection or inflammation, guide the management and, in some cases, evaluate response to therapy.

A wide variety of malignant renal and urinary bladder diseases can be detected on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas was to demonstrate that the spectrum of renal and urinary bladder malignancy that can be evaluated with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the variety of urological tumor types that can be detected on PET/CT and some of the patterns of (18)F-FDG uptake that can be observed in these cases.

Low grade lymphoma may transform into a more aggressive lymphoma and this transformation is usually associated with a poor outcome. A 65year old man presented with two metabolically active splenic lesions on a staging [18F] fluoro-2-deoxy-d-glucose (

A wide variety of malignant gastric diseases can be detected, staged, and followed on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific and some can be seen in certain benign gastric diseases, the aim of this atlas was to demonstrate that the wide histological spectrum of gastric tumors that can be evaluated, staged, and followed with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the utility of PET/CT in these tumors and the imaging characteristics and patterns of (18)F-FDG uptake that can be demonstrated in these cases.

OBJECTIVE. The purpose of this article is to illustrate a wide spectrum of malignant primary and secondary pleural and pericardial diseases imaged with 18F-FDG PET/CT. CONCLUSION. A wide variety of malignant pleural and pericardial diseases can be detected, staged, and monitored by FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas is to show that the spectrum of pleural and pericardial disease that can be evaluated with PET/CT is much broader than current literature would suggest. PET/CT readers and oncologists should be aware of the wide variety of malignancies that can affect the pleura and pericardium and some of the patterns of FDG uptake that can be observed in these cases.

A 73-year-old man suffering from Cowden syndrome with gastrointestinal polyposis was referred for an 18F-FDG PET/CT after a routine gastroscopic biopsy revealed a poorly differentiated adenocarcinoma. The 18F-FDG PET/CT identified 2 foci of FDG-avid gastric adenocarcinoma on the background of extens

A 66-year-old woman with long-standing multiple sclerosis presented with a several month history of diarrhea and weight loss. F-18 FDG PET/CT imaging revealed breast, rectal, and urinary bladder masses which were biopsied to reveal 3 different synchronous primary malignancies. PET/CT is able to detect a variety of synchronous malignancies; however, the situation of detecting 3 different synchronous primaries is extremely rare, and this case highlights the importance of paying close attention to anatomic areas that are difficult to evaluate on PET/CT, even after successfully identifying one or several FDG-avid primary malignancies.

About one-third of patients with Crohn disease develop intraabdominal fistulas, and of these, cholecystocolic fistulas are among the rarest. F-18 FDG PET/CT can detect a vast variety of fistulas, although most are discovered incidentally. We present a very unusual case of a 79-year-old woman referred for an F-18 FDG PET/CT for evaluation of a solitary pulmonary nodule. A colon mass was detected incidentally that appeared to directly invade the gallbladder; however, histologic evaluation after surgery revealed a colon adenocarcinoma, with an adjacent cholecystocolic fistula arising from a transmural fissure ulcer in a nonneoplastic colon segment consistent with clinically silent Crohn disease.

Xerostomia is a significant morbidity of radiation treatment in the management of head and neck cancers. To preserve salivary function, a surgical technique has been developed that involves the transfer of one submandibular gland to the ipsilateral submental space, where it can be shielded during radiation therapy. F-18 FDG PET/CT imaging characteristics of recently or remotely transferred submandibular glands have not been previously described in the literature. We report 2 cases of patients with surgically transferred submandibular glands, which highlight a potential pitfall in the interpretation of PET/CT of the head and neck region in oncologic patients.

Malignant extrarenal rhabdoid tumor (ERRT) is a very rare type of soft-tissue sarcoma with a reported incidence of 0.3% of all soft-tissue sarcomas. Only 7 cases of spinal malignant ERRT have been reported in the literature, and to our knowledge, F-18 FDG PET/CT imaging for staging and evaluation of response to therapy for these tumors has not been previously described. This is a case of an 8-month-old boy with malignant ERRT of the spine, who was staged with F-18 FDG PET/CT, and had his tumor burden assessed with PET/CT after chemotherapy, which altered the subsequent chemotherapy regimen.

A 30-year-old woman was referred for an F-18 fluorodeoxyglucose (FDG) PET/CT to rule out lymphoma, and was found to have an incidental FDG-avid right breast nodule that grew significantly in size and FDG uptake on a subsequent scan, raising suspicion of a growing breast malignancy. Histologic evaluation showed a complex fibroadenoma with adenosis and surrounding ductal hyperplasia. Although variable F-18 FDG uptake in fibroadenomas has been described, a distinction between simple and complex fibroadenomas has not been made in the PET literature, even though complex fibroadenomas have a higher propensity to develop into malignancies. This case shows that a rapidly growing complex fibroadenoma can mimic a breast malignancy on serial F-18 FDG PET/CT scans, showing significant increase in both size and FDG-avidity on follow-up studies.

Angiomatoid fibrous histiocytoma is a very rare tumor that accounts for 0.3% of all soft-tissue tumors, and occurs predominantly in the extremities of adolescents and young adults. It has been classified by the World Health Organization as a tumor of uncertain differentiation with intermediate malignant potential, although recent evidence suggests a myoid or myofibroblastic cell origin. Most examples behave in an indolent manner with a regional recurrence rate of 15% and a rate of metastasis of 1%. We present a 29-year-old woman who was referred for an F-18 FDG PET/CT to evaluate a left shoulder mass. She had multiple local FDG-avid lymph nodes, and initial biopsy was suggestive of epithelioid sarcoma. She was treated with chemotherapy, but a post-therapy PET/CT showed minimal response and radical surgical excision was performed. The histopathology and immunohistochemistry was consistent with angiomatoid fibrous histiocytoma. This case highlights a potential new utility for F-18 FDG PET/CT in the staging and evaluation of response to therapy for this very rare soft-tissue tumor.

To systematically evaluate the diagnostic benefits and inter- and intraobserver reliability of an incremental computed tomographic (CT) protocol in the confirmation of clinically suspected stroke, with combined imaging and clinical data as the reference standard.Institutional review board approval was obtained, and participants gave informed consent. A total of 191 patients (mean age, 67 years +/- 16 [standard deviation]; 105 men) with strokelike symptoms of no more than 3 hours duration were recruited. Blinded review was performed by four readers with limited stroke imaging experience. Diagnostic confidence was recorded on a five-point scale. Logistic regression analysis was used to calculate the difference between the real and observed diagnoses, adjusting for confidence. Predictive effects of observed diagnostic performance and confidence score were quantified with the entropy r(2) value. Sensitivity, specificity, and confidence intervals were calculated while accounting for multiple reader assessments. Receiver operating characteristic (ROC) analyses, including area under the ROC curve, were conducted for three modalities in combination with confidence score. Inter- and intraobserver agreement was established with the Cohen kappa statistic.The final diagnosis was infarct in 64% of the patients, transient ischemic attack in 18%, and stroke mimic in 17%. Large-vessel occlusion occurred in 70% of the patients with an infarct. Sensitivity for stroke determination with noncontrast CT, CT angiography, and CT perfusion increased by 12.4% over that with noncontrast CT and CT angiography and by 18.2% over that with only noncontrast CT for a confidence level of 4 or higher. The incremental protocol was more likely to enable confirmation of clinical stroke diagnosis (odds ratio, 13.3) than was noncontrast CT and CT angiography (odds ratio, 6.4) or noncontrast CT alone (odds ratio, 3.3), The area under the ROC curve was 0.67 for the combination of noncontrast CT and confidence score, 0.72 for the combination of CT angiography and confidence score, and 0.81 for the combination of CT perfusion and confidence score. Inter- and intraobserver agreement increased with progressive sequence use.An incremental stroke protocol that includes CT perfusion increases diagnostic performance for stroke diagnosis and inter- and intraobserver agreement.

Conventional imaging modalities (CIMs) have limited sensitivity and specificity for detection of metastatic prostate cancer. We examined the potential of a first-in-class radiofluorinated small-molecule inhibitor of prostate-specific membrane antigen (PSMA), N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-4-18F-fluorobenzyl-l-cysteine (18F-DCFBC), to detect metastatic hormone-naive (HNPC) and castration-resistant prostate cancer (CRPC). Methods: Seventeen patients were prospectively enrolled (9 HNPC and 8 CRPC); 16 had CIM evidence of new or progressive metastatic prostate cancer and 1 had high clinical suspicion of metastatic disease. 18F-DCFBC PET/CT imaging was obtained with 2 successive PET scans starting at 2 h after injection. Patients were imaged with CIM at approximately the time of PET. A lesion-by-lesion analysis of PET to CIM was performed in the context of either HNPC or CRPC. The patients were followed with available clinical imaging as a reference standard to determine the true nature of identified lesions on PET and CIM. Results: On the lesion-by-lesion analysis, 18F-DCFBC PET was able to detect a larger number of lesions (592 positive with 63 equivocal) than CIM (520 positive with 61 equivocal) overall, in both HNPC and CRPC patients. 18F-DCFBC PET detection of lymph nodes, bone lesions, and visceral lesions was superior to CIM. When intrapatient clustering effects were considered, 18F-DCFBC PET was estimated to be positive in a large proportion of lesions that would be negative or equivocal on CIM (0.45). On follow-up, the sensitivity of 18F-DCFBC PET (0.92) was superior to CIM (0.71). 18F-DCFBC tumor uptake was increased at the later PET time point (∼2.5 h after injection), with background uptake showing a decreasing trend on later PET. Conclusion: PET imaging with 18F-DCFBC, a small-molecule PSMA-targeted radiotracer, detected more lesions than CIM and promises to diagnose and stage patients with metastatic prostate cancer more accurately than current imaging methods.

"Fluorodeoxyglucose (FDG) PET/computed tomography (CT) is used most frequently in the surveillance of iodine-refractory differentiated thyroid cancer with increased thyroglobulin level after therapy. This article evaluates the impact of FDG-PET/CT on clinical management and the prognostic implications of a positive scan. In the studies reviewed, FDG-PET/CT changed the course of management in 14% to 78% of patients with suspected recurrence, and a positive scan was associated with poorer survival. Similar conclusions are supported in the literature for anaplastic and medullary thyroid cancers, although these are based on fewer studies on account of the lower prevalence of these subtypes."

A 26-year-old man with a prior history of acute leukemia that was treated with a stem cell transplant (SCT) was referred for an F-18 FDG PET/CT to assess suspicious new gastric mucosal lesions. The lesions were FDG-avid and were histologically proven to be acute lymphoblastic leukemia (ALL). Extramedullary relapse of ALL after SCT is very rare, with only 60 cases reported in the literature, and the role of F-18 FDG PET/CT in monitoring for ALL relapse following SCT has not been previously investigated. This rare case report highlights the use of F-18 FDG PET/CT in staging gastric relapse of ALL following SCT.

Chondromyxoid fibroma (CMF) is a rare benign bone tumor of chondroid origin that occurs mostly in the metaphyses of long bones. CMF can occasionally mimic a chondrosarcoma on CT, and the literature on the 18F-FDG PET/CT imaging characteristics of CMF tumors is limited. In the presented case, a large histologically proven CMF chest wall mass was initially misinterpreted as a chondrosarcoma. This case highlights a potential pitfall in the PET/CT evaluation of these rare benign bone tumors.

A previously healthy 27-year-old woman presented with a thyroid goiter, symptoms of thyrotoxicosis, and mild respiratory obstruction. The serum thyroid stimulating hormone (TSH) was suppressed, serum T4 was elevated, and 24-hour radioiodine uptake was elevated at 59%. Thyroid scintigraphy showed intense uptake in an enlarged gland, with a cold nodule on the right, and a large isolated mass in the mediastinum, with very mild uptake. Total thyroidectomy and excision of the mediastinal mass revealed multiple pathologies: Graves disease in the thyroid gland with an incidental papillary thyroid carcinoma, and a benign sequestered intrathoracic multinodular goiter. Thyroid carcinoma can develop in a gland affected by Graves disease, however, the presence of concomitant sequestered intrathoracic thyroid tissue unaffected by Graves disease is highly unusual and has not been previously described. We present the scintigraphic findings, and several theories that could help explain these findings.

UnlabelledThere has been no established qualitative system of interpretation for therapy response assessment using PET/CT for head and neck cancers. The objective of this study was to validate the Hopkins interpretation system to assess therapy response and survival outcome in head and neck squamous cell cancer patients (HNSCC).MethodsThe study included 214 biopsy-proven HNSCC patients who underwent a posttherapy PET/CT study, between 5 and 24 wk after completion of treatment. The median follow-up was 27 mo. PET/CT studies were interpreted by 3 nuclear medicine physicians, independently. The studies were scored using a qualitative 5-point scale, for the primary tumor, for the right and left neck, and for overall assessment. Scores 1, 2, and 3 were considered negative for tumors, and scores 4 and 5 were considered positive for tumors. The Cohen κ coefficient (κ) was calculated to measure interreader agreement. Overall survival (OS) and progression-free survival (PFS) were analyzed by Kaplan-Meier plots with a Mantel-Cox log-rank test and Gehan Breslow Wilcoxon test for comparisons.ResultsOf the 214 patients, 175 were men and 39 were women. There was 85.98%, 95.33%, 93.46%, and 87.38% agreement between the readers for overall, left neck, right neck, and primary tumor site response scores, respectively. The corresponding κ coefficients for interreader agreement between readers were, 0.69-0.79, 0.68-0.83, 0.69-0.87, and 0.79-0.86 for overall, left neck, right neck, and primary tumor site response, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of the therapy assessment were 68.1%, 92.2%, 71.1%, 91.1%, and 86.9%, respectively. Cox multivariate regression analysis showed human papillomavirus (HPV) status and PET/CT interpretation were the only factors associated with PFS and OS. Among the HPV-positive patients (n = 123), there was a significant difference in PFS (hazard ratio [HR], 0.14; 95% confidence interval, 0.03-0.57; P = 0.0063) and OS (HR, 0.01; 95% confidence interval, 0.00-0.13; P = 0.0006) between the patients who had a score negative for residual tumor versus positive for residual tumor. A similar significant difference was observed in PFS and OS for all patients. There was also a significant difference in the PFS of patients with PET-avid residual disease in one site versus multiple sites in the neck (HR, 0.23; log-rank P = 0.004).ConclusionThe Hopkins 5-point qualitative therapy response interpretation criteria for head and neck PET/CT has substantial interreader agreement and excellent negative predictive value and predicts OS and PFS in patients with HPV-positive HNSCC.

Gastric neuroendocrine carcinomas (NEC) are very rare, aggressive tumors of the stomach that are distinct from the more benign neuroendocrine tumors, sometimes referred to as "gastric carcinoids." We present 3 cases of gastric NEC representing various histological subtypes that were successfully staged and followed with F-FDG PET/CT, impacting therapeutic management in each case.

A 36-year-old woman presented with a 5-month history of a growing left thigh mass, causing difficulty walking. Biopsy revealed a malignant epithelioid hemangioendothelioma (EHE), and the patient was referred for a staging F-18 FDG PET/CT that showed intense FDG uptake in the thigh mass, but no FDG-avid local lymph nodes or distant metastases. A few reports have noted the usefulness of F-18 FDG PET/CT imaging in the staging of EHEs in the lung, liver, and bone marrow. This rare study highlights the usefulness of F-18 FDG PET/CT in the staging of malignant EHE of the soft tissues of the extremities.

We present a case of a woman with ulcerative colitis who was referred for an F-18 FDG PET/CT after a suspicious colonoscopy and biopsy. PET/CT showed multiple elongated foci of intense FDG uptake in the colon, a pattern commonly reported with inflammatory bowel disease; however, the possibility of lymphoma was raised. Reevaluation of the biopsies with immunohistochemistry and molecular studies revealed a peripheral T-cell lymphoma and the patient was treated with a total colectomy. In this case, F-18 FDG PET/CT was very useful in determining the extent of the disease. This case also highlights a potential pitfall whereby the tubular and multifocal appearance of this lymphoma subtype can mimic the appearance of bowel involved by inflammatory bowel disease especially on novel techniques such as PET/CT enterography and PET/CT colonography.

A 66-year-old man, who presented with bright red blood per rectum, was referred for an (18)F-FDG PET/CT after colonoscopy showed two suspicious colon masses, which were biopsied to reveal an adenocarcinoma of unknown origin. PET/CT showed two intensely FDG-avid colon masses as well as an unsuspected FDG-avid lung mass, which was biopsied to reveal a primary lung adenocarcinoma. Immunohistochemistry confirmed the two colon metastases were of pulmonary origin. It is extremely rare for lung carcinoma to present with symptomatic colon metastases, with only 11 cases described in the literature. We report the first case of the utility of (18)F-FDG PET/CT in staging a patient who presented with symptomatic colon metastases of an unknown primary lung malignancy.

Bilateral renal masses are uncommon but can raise a strong suspicion of primary or secondary malignancy, especially during the initial work-up of an oncology patient. Renal oncocytomas are benign renal tumors that are commonly discovered incidentally on diagnostic imaging with a small percentage occurring bilaterally. Although (18)F-FDG uptake in renal oncocytomas has been described, a case of a bilateral (18)F-FDG-avid renal oncocytoma has not been previously reported in the literature. A variety of malignant causes of bilateral (18)F-FDG positive renal masses are known, however it is important to include this benign etiology in the differential diagnosis. We report an unusual case of an incidental bilateral renal oncocytoma evaluated with contrast enhanced CT and (18)F-FDG PET/CT.

This is a case of a 52-year-old woman who underwent a hyster-ectomy to treat a large uterine perivascular epithelioid cell tumor. She wasfollowed with serial F-18 FDG PET/CT scans due to positive surgicalmargins and vascular invasion on pathology. Initial surveillance PET/CTperformed 6 months post surgery was negative; however, a second surveil-lance PET/CT performed 12 months post surgery showed an intenselyFDG-avid recurrence in the pelvic surgical site. The patient received localradiotherapy, 2 cycles of taxol and carboplatin, and was placed on imatinibmesylate (Gleevec). A final PET/CT performed 6 months after initiation oftherapy showed rapidly disseminating metastatic disease and the patient died1 month later. This rare report highlights a potentially new utility of F-18FDG PET/CT for surveillance of recurrence of a malignant uterine perivas-cular epithelioid cell tumor, as well as for evaluation of response to therapy. Key Words: malignant perivascular epithelioid cell tumor, PEComa,uterus tumors, FDG, PET/CT(

It is estimated that osteoporosis is responsible for about 300 000 hip fractures per year in the United States. Effective prevention of these fractures has been demonstrated using bisphosphonates. However, their mechanism of action has not been elucidated. Furthermore, the precise effect of bisphosphonates on the femoral neck and surrounding areas has never been studied. We are interested in establishing a protocol to analyze the bone quality of proximal femurs from patients treated with bisphosphonates. Following hip replacement surgery, the aim is to determine whether imaging and compression testing of cancellous bone from the discarded femoral necks can accurately assess the bone’s microarchitectural and biomechanical properties, respectively. To validate the technique, it was first tested on an untreated population. A bone biopsy trephine was used to extract cylindrical cores of trabecular bone from the centre of femoral necks. Densitometry, microcomputed tomography, and compression testing were used to assess the quality of bone in these samples. The compressive strength was found to be directly proportional to the modulus (i.e. stiffness) of the samples, thus reproducing previous findings. The relative porosity and, to a lesser extent, the bone mineral density were capable of predicting the quality of cancellous bone. In conclusion, a protocol to analyze the bone quality in human femoral necks using μCT and biomechanical compression testing was successfully established. It will be applied in a clinical setting to analyze bones from bisphosphonate-treated patients following total hip replacement.

This report of an 82-year-old man who presented with a 3-week history of an enlarging left axillary mass and mild fevers, highlights the usefulness of both gallium-67 and F-18 FDG PET/CT imaging in the staging of histiocytic sarcoma. While PET/CT was superior in determining the extent of the disease, gallium can be used to help stage the disease in centers where PET/CT is not available.