Physiologic uterine uptake of FDG during menstruation demonstrated with serial combined positron emission tomography and computed tomography.

F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has been used extensively to stage, restage, and follow neoplastic disease. However, focal accumulation of FDG may cause false-positive results in certain physiologic conditions. In this report, a unique PET and computed tomography (CT) combination scan helped define physiologic accumulation of FDG in the uterus during menstruation in a 40-year-old woman with a history of rectal melanoma and possible recurrent disease. An initial PET study, performed during menstruation, was followed immediately by a PET-CT scan, which showed marked accumulation of FDG in the posterior pelvis, localized to a retroverted uterus. An FDG PET-CT scan repeated 2 weeks later confirmed resolution of this "lesion." Thus, combined PET-CT correctly differentiated physiologic FDG uptake in a retroverted uterus from recurrent rectal melanoma. This case shows that physiologic FDG accumulation in the uterus should be considered when focal FDG accumulation is observed in the pelvis in women of reproductive age.     

Gallbladder metastasis from malignant melanoma: diagnosis with FDG PET/CT

Melanoma with metastasis to the gallbladder is sometimes seen on autopsy but is rarely seen in living patients, in part because it is often asymptomatic. A 67-year-old man with a history of malignant melanoma in situ underwent an F-18 FDG PET/CT scan, which showed a gallbladder focus (SUV 16.9). Four months later, on the repeat FDG PET/CT scan, a new lesion in the gallbladder was noted. Laparoscopic cholecystectomy was done and histopathologic findings were consistent with gallbladder metastasis of melanoma. PET/CT detects metastasis at unusual sites accurately and is helpful in correct staging and management of patients with melanoma.     

The effect of fluorine-18 fluorodeoxyglucose positron emission tomography on the management of cutaneous malignant melanoma

PURPOSE: To assess the effect of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) on the treatment of patients with cutaneous malignant melanoma. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 38 patients with newly diagnosed (n = 25) and recurrent (n = 13) cutaneous melanoma who were referred for evaluation with FDG PET imaging at our institution. We compared the PET findings with computed tomography (CT), which was available in 21 (55%) patients, and tabulated the changes in the diagnostic evaluation and therapeutic management that were prompted by PET during a follow-up period of 10 to 36 months. RESULTS: Compared with PET, the extent of disease was underestimated by CT in 5 (13%) patients. Planned surgical resection of metastases was canceled in two of these patients. In another patient, surveillance PET detected an unsuspected hypermetabolic abdominal mass that was noted on a subsequent CT to arise from the small bowel. The mass was found to be jejunal metastatic melanoma at the time of resection. Overall, PET influenced surgical management in 3 (8%) patients, but it did not affect the wait-and-watch strategy or decision to initiate immunotherapy in the others. CONCLUSIONS: FDG PET contributes important information not provided by CT and has a substantial effect on the clinical management of patients with malignant melanoma.     

18F-fluorodeoxyglucose positron emission tomography and computed tomography in anaplastic thyroid cancer

Purpose

Our aim was to evaluate in anaplastic thyroid carcinoma (ATC) patients the value of ¹⁸F-FDG PET/CT compared with total body computed tomography (CT) using intravenous contrast material for initial staging, prognostic assessment, therapeutic monitoring and follow-up.

Methods

Twenty consecutive ATC patients underwent PET/CT for initial staging. PET/CT was performed again during follow-up. The gold standard was progression on imaging follow-up (CT or PET/CT) or confirmation with another imaging modality.

Results

A total of 265 lesions in 63 organs were depicted in 18 patients. Thirty-five per cent of involved organs were demonstrated only with PET/CT and one involved organ only with CT. In three patients, the extent of disease was significantly changed with PET/CT that demonstrated unknown metastases. Initial treatment modalities were modified by PET/CT findings in 25% of cases. The volume of FDG uptake (≥300 ml) and the intensity of FDG uptake (SUV_max ≥18) were significant prognostic factors for survival. PET/CT permitted an earlier assessment of tumour response to treatment than CT in 4 of the 11 patients in whom both examinations were performed. After treatment with combined radiotherapy and chemotherapy, only the two patients with a negative control PET/CT had a confirmed complete remission at 14 and 38 months; all eight patients who had persistent FDG uptake during treatment had a clinical recurrence and died.

Conclusion

FDG PET/CT appears to be the reference imaging modality for ATC at initial staging and seems promising in the early evaluation of treatment response and follow-up.     

Findings of intramediastinal gossypiboma with F-18 FDG PET in a melanoma patient

FDG PET/CT scan was performed to evaluate recurrence in an asymptomatic 64-year-old man with a history of melanoma in the left posterior ear. PET/CT images showed an intense ring-shaped area of FDG activity in the posterior mediastinum in a large posterior mediastinal mass. However, further evaluation indicated that this activity was caused by an intramediastinal gossypiboma after coronary artery bypass graft surgery 4 years before the PET/CT scan.     

Metastatic melanoma causing complete atrioventricular block--the role of FDG PET/CT in diagnosis

Cardiac involvement with melanoma is not uncommon, but only a few are reported to have antemortem diagnosis. Here, we report a case of a patient with melanoma causing complete atrioventricular block, which is a rare complication of this condition. The patient had multiple metastatic lesions from melanoma and had undergone multiple surgeries and later developed asystole which was treated with a pacemaker. Echocardiogram was performed but no metastatic lesion suggested or detected. Cardiac metastasis was not suspected until 5 months later when the patient underwent a FDG PET/CT for a whole-body evaluation which was interpreted to be suspicious for metastasis to the myocardium. This was confirmed by a repeat myocardial FDG PET scan. In this case report, the role of FDG PET in melanoma patients with cardiac involvement is discussed.     

Talc pleurodesis mimics pleural metastases: differentiation with positron emission tomography/computed tomography

Talc pleurodesis is a technique used in the treatment of patients with persistent pleural effusions or pneumothorax not amenable to other treatment. These are commonly seen in patients with malignant thoracic neoplasms. Radiographic abnormalities resulting from prior talc pleurodesis could be confused with progression of the underlying neoplastic process. Positron emission tomography with F-18 fluorodeoxyglucose (FDG-PET) might be unable to distinguish between malignant and benign inflammatory processes. This report demonstrates the use of combined positron emission tomography/computed tomography (PET/CT) in a patient with a history of both malignant neoplasm and a prior talc pleurodesis. Fusion of PET and CT studies could add information that CT and PET alone cannot. This could alter the diagnostic and therapeutic course for patients with a history of both thoracic neoplasm and talc pleurodesis.     

Tear of plantar fascia and tibiocalcaneal ligament with positive F-18 FDG PET findings

Although PET/CT imaging provides the most comprehensive evaluation of cancer, coexisting hypermetabolic benign processes may interfere with the staging of aggressive malignancy such as melanoma and extranodal non-Hodgkin lymphoma. Acute and subacute skeletal injuries have been reported as false-positive PET findings. The authors present additional mimickers of high metabolic malignancy with a case of stage III recurrent melanoma featuring F-18 FDG accumulation at partially torn medial plantar fascia and tibiocalcaneal ligament of the left foot.     

Fluor-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in malignant melanoma. Diagnostic comparison with conventional imaging methods

Purpose: To assess the diagnostic value of fluor-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in screening for melanoma metastases.Material and Methods: The case records of 94 melanoma patients who had been examined by whole-body FDG-PET between 1995 and 1999 were evaluated retrospectively. Forty patients showed evidence of lymphogenous and 42 of hematogenous metastasis. The maximal interval between PET and the diagnostic procedure under comparison was 2 weeks. Confirmation of the findings was based on histology or the clinical or radiological course.Results: In 24 patients, all diagnostic examinations including CT had been performed within 2 weeks from PET. In no case did PET change the staging. In 13 patients, PET agreed with morphological diagnosis in the number of metastatically invaded organs. This included 3 patients without metastases. The estimated number of organs invaded by metastases was higher with PET in 5 patients and higher with morphological imaging techniques in 6 patients. Among the PET findings with higher or equivocal counts of organs with metastases there were 2 confirmed false-positive findings.Conclusion: In a selected patient population, FDG-PET was found to be inferior to CT for diagnosing lung and liver metastases. The supplementary use of FDG-PET is not generally of value once metastasis has been established.     

F-18 FDG PET positive hilar and mediastinal lymphadenopathy mimicking metastatic disease in a melanoma patient treated with interferon-alpha-2b

A 49-year-old man with a history of recurrent melanoma in the parotid was treated with parotidectomy, external beam radiation, and high-dose interferon-alpha-2b. Combined F-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) performed for restaging demonstrated multiple bilateral hilar and mediastinal hypermetabolic foci corresponding to hilar and mediastinal lymphadenopathy. Cytologic specimens obtained by bronchoscopy were negative for malignancy, revealing reactive lymph nodes. Subsequent FDG PET/CT showed regression of the findings. Awareness of possible interferon-associated reaction in melanoma patients who undergo FDG PET is important to avoid pitfalls in the interpretation.     

Solitary splenic metastasis in a patient with a malignant melanoma diagnosed with F-18-FDG PET scanning

A 71-year-old woman with a history of stage III melanoma was hospitalized for evaluating fever of unknown origin and severe left upper quadrant abdominal pain. A computed tomography scan of the abdomen revealed a solitary lesion in the spleen, 10.5 x 10.4 x 10.1-cm, causing splenomegaly. Fused F-18 FDG PET/CT images revealed a solitary splenic metastasis and a focus of increased uptake in the region of the previously removed melanoma at the right scapula. Based on the clinical findings and CT and PET scans, malignant melanoma (stage IV) was diagnosed. Splenectomy was performed subsequently. The histopathologic finding was consistent with a metastasis of a melanoma.     

Follicular dendritic sarcoma within a focus of Castleman's disease. Serial FDG PET/CT in the follow up of recurrence with histopathologic confirmation

We report the case of a 30 year-old man with previous history of melanoma and new diagnoses of localized abdominal Castleman's disease with a focus of follicular dendritic sarcoma within the Castleman's tumor. He presented soon after with a single enlarged abdominal lymph node characterized and followed-up by FDG PET/CT as a low grade malignancy consistent with Castleman's recurrence. However, other imaging techniques raised the possibility of sarcoma/ melanoma recurrence. Final surgical resection allowed histological confirmation of the FDG PET/CT findings. To our knowledge, this is one of the few cases in the literature of Castleman's disease and follicular dendritic sarcoma association in the same focus. This is the first paper to our knowledge to use FDG PET/CT as the follow-up imaging tool for serial characterization of recurrence of Castleman's disease and follicular dendritic sarcoma. FDG PET/CT may be useful in the differentiation between Castleman's disease and malignancies associated with this disease.     

Motion management in positron emission tomography/computed tomography for radiation treatment planning

Hybrid positron emission tomography (PET)/computed tomography (CT) scanners combine, in a unique gantry, 2 of the most important diagnostic imaging systems, a CT and a PET tomograph, enabling anatomical (CT) and functional (PET) studies to be performed in a single study session. Furthermore, as the 2 scanners use the same spatial coordinate system, the reconstructed CT and PET images are spatially co-registered, allowing an accurate localization of the functional signal over the corresponding anatomical structure. This peculiarity of the hybrid PET/CT system results in improved tumor characterization for oncological applications, and more recently, it was found to be also useful for target volume definition (TVD) and treatment planning in radiotherapy (RT) applications. In fact, the use of combined PET/CT information has been shown to improve the RT treatment plan when compared with that obtained by a CT alone. A limiting factor to the accuracy of TVD by PET/CT is organ and tumor motion, which is mainly due to patient respiration. In fact, respiratory motion has a degrading effect on PET/CT image quality, and this is also critical for TVD, as it can lead to possible tumor missing or undertreatment. Thus, the management of respiratory motion is becoming an increasingly essential component in RT treatment planning; indeed, it has been recognized that the use of personalized motion information can improve TVD and, consequently, permit increased tumor dosage while sparing surrounding healthy tissues and organs at risk. This review describes the methods used for motion management in PET/CT for radiation treatment planning. The article covers the following: (1) problems caused by organ and lesion motion owing to respiration, and the artifacts generated on CT, PET, and PET/CT images; (2) data acquisition and processing techniques used to manage respiratory motion in PET/CT studies; and (3) the use of personalized motion information for TVD and radiation treatment planning.     

The role of fluorine-18 deoxyglucose positron emission tomography in the management of patients with metastatic melanoma: impact on surgical decision making

Malignant melanoma can metastasize to almost any organ site. Optimal management requires sensitive radiographic evaluation of the entire body. The optimal management of patients with metastatic melanoma requires accurate assessment of extent of disease (EOD). The objective of this study was to evaluate the accuracy of fluorine-18 deoxyglucose (FDG) whole-body positron emission tomography (PET) in determination of EOD in patients with metastatic melanoma and its impact on surgical and medical management decisions. Forty-nine patients (30 men, 19 women; aged 25-83 years) with known or suspected metastatic melanoma underwent EOD evaluation using computerized tomography (CT) of the chest, abdomen, and pelvis, and magnetic resonance imaging (MRI) of the brain. After formulation of an initial treatment plan, the patients underwent FDG-PET imaging. The EOD determined by PET was compared with physical examination and conventional radiography findings. Fifty-one lesions were pathologically evaluated. The impact of PET on patient management was assessed based on the alterations made in the initial treatment plan after reevaluation of the patients using the information obtained by PET. The PET scan identified more metastatic sites in 27 of 49 (55%) of the patients who had undergone a complete set of imaging studies, including CT scans of the chest, abdomen, and pelvis, and MRI of the brain. In 6 of those 27 patients, PET detected disease outside the fields of CT and MRI. Fifty-one lesions were resected surgically. Of these, 44 were pathologically confirmed to be melanoma. All lesions larger than 1 cm (29 of 29) were positive on PET, whereas only 2 of 15 (13%) lesions smaller than 1 cm were detected by PET. The results of PET led treatment changes in 24 patients (49%). Eighteen of these changes (75%) were surgical. In 12 cases (67%), the planned operative procedure was cancelled, and in 6 cases (33%), an additional operation(s) was performed. In 6 of 24 (25%) patients, biochemotherapy, radiation therapy, or an experimental immunotherapy protocol was prompted by identification of new foci of disease. Compared with conventional imaging, FDG-PET provides more accurate assessment of EOD in patients with metastatic melanoma. Significant surgical and medical treatment alterations were made based on PET results.     

Clinical value of 18F-fluorodihydroxyphenylalanine positron emission tomography/computed tomography (18F-DOPA PET/CT) for detecting pheochromocytoma

Purpose

In detecting pheochromocytoma (PHEO), positron emission tomography (PET) with the radiolabelled amine precursor ¹⁸F-fluorodihydroxyphenylalanine (¹⁸F-DOPA) offers excellent specificity, while computed tomography (CT) provides high sensitivity and ability to localize lesions; therefore, the combination of these modalities could be advantageous in this setting. The aim of this study was to investigate whether combined ¹⁸F-DOPA PET/CT more accurately detects and localizes PHEO lesions than does each modality alone.

Methods

¹⁸F-DOPA PET, CT and ¹⁸F-DOPA PET/CT images of 25 consecutive patients undergoing diagnostic scanning of suspected sporadic or multiple endocrine neoplasia type 2 syndrome-associated PHEO were reviewed retrospectively in randomized sequence. Two blinded observers scored the images regarding the likelihood of PHEO being present and localizable. Results were correlated with subsequent clinical history and, when available, histology.

Results

Of the 19 lesions detected by all three modalities, PET identified each as positive for PHEO, but was unable to definitively localize 15 of 19 (79%). CT could definitively localize all 19 lesions, but could not definitively diagnose or exclude PHEO in 18 of 19 (95%) lesions. Furthermore, CT falsely identified as negative for PHEO one lesion which was judged to be positive for this tumor by both PET and PET/CT. Only in PET/CT scans were all 19 lesions accurately characterized and localized. On a per-patient basis, the sensitivity of ¹⁸F-DOPA PET/CT for PHEO was 100% and the specificity 88%, with a 100% positive predictive value and an 88% negative predictive value.

Conclusion

¹⁸F-DOPA PET/CT more accurately diagnoses and localizes adrenal and extra-adrenal masses suspicious for PHEO than do ¹⁸F-DOPA PET or CT alone.     

F-18 Fluorodeoxyglucose PET/CT and Post Hoc PET/MRI in a Case of Primary Meningeal Melanomatosis

Primary meningeal melanomatosis is a rare, aggressive variant of primary malignant melanoma of the central nervous system, which arises from melanocytes within the leptomeninges and carries a poor prognosis. We report a case of primary meningeal melanomatosis in a 17-year-old man, which was diagnosed with ¹⁸F-fluorodeoxyglucose (F-18 FDG) PET/CT, and post hoc F-18 FDG PET/MRI fusion images. Whole-body F-18 FDG PET/CT was helpful in ruling out the extracranial origin of melanoma lesions, and in assessing the therapeutic response. Post hoc PET/MRI fusion images facilitated the correlation between PET and MRI images and demonstrated the hypermetabolic lesions more accurately than the unenhanced PET/CT images. Whole body F-18 FDG PET/CT and post hoc PET/MRI images might help clinicians determine the best therapeutic strategy for patients with primary meningeal melanomatosis.     

Positron-emission tomography and computed tomography of cystic pancreatic masses

AIM: To investigate the sensitivity and specificity of computed tomography (CT), positron-emission tomography (PET), and both methods in combination, for determining whether cystic pancreatic tumours are malignant. MATERIALS AND METHODS: We retrospectively identified all patients with cystic pancreatic tumours who underwent separate PET and contrast-enhanced CT examinations within a 1-month interval. Tumours were classified as benign or malignant on CT (two radiologists, independently), PET [a reported standardized uptake value (SUV) of 2.5 was taken as the cut-off between benign and malignant], and with PET and CT images together (two radiologists, in consensus). Readers were blinded to pathological and other radiological findings. Mean patient age and lesion size were compared between benign and malignant groups using Student's t-test. For CT findings, odds ratios (OR) and confidence intervals (CI) were calculated using multivariate logistic regression models. For CT, PET, and the combined images, sensitivities and specificities were calculated, and compared between groups using Fisher's exact test. RESULTS: Thirty patients were identified. The best CT predictor of malignancy was size; mean diameter was 2.3 cm (benign) and 4.1 cm (malignant) (p<0.01); OR was 2.80 (95% CI, 1.26-6.20). Sensitivities of CT, PET and combined PET/CT images were 67-71, 57, and 86%, respectively. PET/CT was more sensitive than PET (p<0.01) or CT (p<0.01) alone. Specificities of CT, PET, and combined PET/CT images were 87-90, 65, and 91%, respectively. PET/CT was more specific than PET (p<0.01) but not CT (p>0.05). CONCLUSION: The sensitivity and specificity of combined PET and CT images is comparable with or superior to either CT or PET alone in determining malignancy in cystic pancreatic lesions.     

18F-FDG PET/CT在黑色素瘤中的应用价值

目的 探讨18F-脱氧葡萄糖(FDG)PET/CT显像在黑色素瘤诊断、临床分期及监测治疗后肿瘤复发与转移灶中的应用价值.方法 黑色素瘤患者61例,均进行18F-FDG PET/CT全身显像.所有PET、CT及PET/CT融合图像均通过融合软件进行帧对帧对比分析.肿瘤病灶根据病理学检查、多种影像学检查及临床随访结果诊断.结果 18F-FDG PET/CT显像对黑色素瘤病灶检出的灵敏度、特异性和准确性分别为90.9%(40/44)、88.2%(15/17)和90.2%(55/61).其中12例治疗前患者中,18F-FDG PET/CT显像诊断的灵敏度为83.3%(10/12).在黑色素瘤病灶局部切除、尚未进行其他治疗的9例患者中,5例残余病灶18F-FDG PET/CT显像检出3例;4例远处转移灶患者全被检出,提高了临床分期,改变了治疗方案.首先发现转移性黑色素瘤病灶并且手术切除后,寻找原发灶的7例患者中,18F-FDG PET/CT检出原发灶2例,4例其他转移灶全被检出.黑色素瘤患者根治术后监测肿瘤复发或转移患者33例,18F-FDG PET/CT显像灵敏度、特异性和准确性分别为100.0%(19/19)、85.7%(12/14)和93.9%(31/33).与同期临床其他影像学检查比较,18F-FDG PET/CT显像发现更多,33例患者中,16例(48.5%)病灶提高临床分期;7例(21.2%)排除可疑病灶,降低临床分期;10例(30.3%)检出病灶与临床一致.结论 18F-FDG PET/CT显像对于黑色素瘤的诊断,残余病灶、复发病灶及转移灶的检出,临床分期的明确具有重要价值.     

Positron emission tomography/computed tomography: protocol issues and options

Combined positron emission tomography/computed tomography (PET/CT) became FDA-approved for clinical use in late 2001. There are several design advantages of combined PET/CT over PET and CT acquired on separate devices, including more accurate CT and PET data co-registration, improved lesion localization, consolidation of imaging studies, and reduced scan times compared to dedicated PET. There are several protocols that can used to scan patients on combined PET/CT devices. Although there is no single "correct" protocol for performing a PET/CT scan, the use of oral and intravenous contrast media may improve the diagnostic value of the CT component. Whether to utilize contrast media depends on important clinical variables, including the specific type of tumor and the likelihood of encountering viable abdominal and pelvic malignancy. This article discusses various protocols pertinent to PET/CT imaging, including how the CT portion of a PET/CT scan can be performed and optimized, as well as PET/CT interpretation and reporting issues.     

Dual modality imaging of positron emission tomography-computed tomography (PET-CT) in evaluation of postoperative renal cancer patients

Objective

The aim of our study was to determine the role of PET-CT in detection of recurrence and metastasis of renal cell carcinoma.