Nonossifying fibroma can mimic residual lymphoma in FDG PET: additional value of combined PET/CT

A 12-year-old girl was diagnosed with Hodgkin's lymphoma and underwent conventional cross-sectional imaging for initial staging. Chemotherapy was given according to standard pediatric protocols. At the end of therapy, an F-18 FDG PET/CT examination was performed to evaluate the therapeutic response. The scan demonstrated focal uptake of FDG in the right distal femur and residual lymphoma was taken into consideration. However, findings in the coregistered CT scan were consistent with nonossfiying fibroma, a common benign skeletal lesion. Combined PET/CT imaging can be helpful to identify benign bone lesions mimicking metastatic or residual disease in F-18 FDG PET as illustrated by this case.     

Disseminated extranodal NK/T-cell lymphoma, nasal type, with multiple subcutaneous nodules: utility of 18F-FDG PET in staging

A 49-year-old man presented with a left nasal cavity mass, biopsy of which revealed extranodal NK/T cell lymphoma. A PET-CT scan showed increased F-18 FDG uptake in the nasal mass, anterior mediastinal lymph nodes, and multiple subcutaneous nodular deposits in the chest wall, gluteal region, and right femoral areas. The patient achieved complete remission with salvage l-asparaginase therapy after failing first-line standard anthracycline-based chemotherapy. PET-CT was very useful in detecting subcutaneous nodules consistent with widespread dissemination. There is limited literature data on the use of the PET scan in the diagnosis and staging of extranodal nasal NK/T-cell lymphomas. Our case highlights the important role of F-18 FDG PET in the staging of these patients.     

Differentiation between malignant and benign pathologic fractures with F-18-fluoro-2-deoxy-<Emphasis Type="SmallCaps">D</Emphasis>-glucose positron emission tomography/computed tomography

Objective To evaluate the efficacy of F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET/CT) in differentiating malignant from benign pathologic fractures. Materials and methods F-18 FDG PET/CT was performed on 34 patients with pathologic fractures between May 2004 and June 2007. Fractures were located in tubular bones (26), in the pelvis (six), in the spine (one) and in a rib (one). The FDG uptake pattern at the fracture site was described, whether FDG uptake occurred in the marrow or cortex and soft tissue. Maximum standardized uptake values (SUVmax, the largest value at the region of interest) were measured at the fracture site, including cortical bone, bone marrow and soft tissue. As a reference standard, biopsy was used for 12 patients and clinical follow-up for 22 patients. Sensitivity, specificity and diagnostic accuracy of PET/CT were calculated. Results There were 19 malignant and 15 benign fractures. In the malignant fractures, PET/CT demonstrated high (mean SUVmax 12.0, range 4.3 to 45.7) F-18 FDG uptake in bone marrow in most cases (17 of 19). In benign fractures, there was low FDG uptake (mean SUVmax 2.9, range 0.6 to 5.5) within cortical bone or adjacent soft tissue around the fracture, rarely in the marrow. There were significant differences in the pattern of intramedullary FDG uptake (P < 0.001) and in the mean SUVmax (P < 0.01) between malignant and benign fractures. The sensitivity, specificity and diagnostic accuracy of F-18 FDG PET/CT were 89.5%, 86.7% and 88.2%, respectively, with a cut-off SUVmax set at 4.7. The time interval between fracture and PET/CT did not significantly influence FDG uptake at the fracture site. Conclusion F-18 FDG PET/CT reliably differentiated between malignant and benign fractures based on the SUVmax and based on medullary uptake, which was characteristic for malignant fractures. This research was supported by the Yeungnam University research grants in 2007.     

Squamous papilloma of the oral cavity and oropharynx on 18F-FDG PET/CT imaging

Squamous papilloma is one of the most common benign neoplasms of the oral cavity and oropharynx. The (18)F-FDG PET/CT metabolic phenotype of this entity has not been described. We document the incidental finding of a hypermetabolic lesion at the right base of the tongue on an FDG PET/CT that proved to be squamous papilloma. The maximum standard uptake value was high at 7.0 g/ml. We conclude that oral cavity squamous papilloma can present with an intensely hypermetabolic phenotype on (18)F- FDG PET/CT. This benign entity should be included in the differential diagnosis of FDG-positive oral and oropharyngeal lesions.     

Paget disease of the humerus mimicking metastatic disease in a patient with metastatic malignant mesothelioma on whole body F-18 FDG PET/CT

A 71-year-old man with newly diagnosed malignant mesothelioma was referred for an F-18 FDG PET/CT study to evaluate the extent of disease. PET showed mild FDG uptake in the right chest, corresponding to a lobulated, mass-like right pleural effusion versus thickening involving the entire right pleural space, and some mediastinal involvement, on the accompanying CT scan. In addition, marked FDG uptake was seen in the proximal left humerus, suspicious for an osseous metastasis. The corresponding CT scan findings of cortical thickening and a "Swiss cheese" appearance were most consistent with Paget disease. The intense FDG uptake in an osseous lesion on FDG-PET in our case reminds us of the variable nature of FDG uptake in Paget disease, the possibility of false-positive findings on FDG-PET in patients with cancer, and the usefulness of the fusion techniques in the evaluation of skeletal lesions, with the potential for discriminating between benign Paget disease and other pathologic bone findings.     

Incidental detection of bilateral elastofibroma dorsi with F-18 FDG PET/CT

An 83-year-old asymptomatic woman with a history of breast cancer treated with resection, radiation, and chemotherapy was studied with F-18 FDG positron emission tomography/computed tomography (PET/CT) for staging purposes. The whole-body F-18 FDG PET/CT images revealed poorly circumscribed, bilateral soft tissue masses between the inferior tips of the scapulae and chest wall with a moderate degree of F-18 FDG accumulation. The maximum standardized uptake values were 2.8 for both the left and right lesions. A biopsy or further imaging was not recommended because the lesions were asymptomatic, bilateral, and their imaging features were diagnostic for elastofibroma dorsi. Comparison to a CT scan performed 2 years earlier demonstrated stability of the lesions, further supporting our diagnosis. Recognition of this moderately metabolic benign entity in oncologic patients will avoid unnecessary medical, radiologic, or surgical interventions.     

Follicular Lymphoma mimicking Metastatic Nodes on the F-18 FDG PET/CT and MRI for Staging of Endometrial Cancer

A 53-year-old woman was diagnosed with endometrial carcinoma by vaginal bleeding. F-18 fluorodeoxy glucose positron emission tomography PET/CT (F-18 FDG PET/CT) scan for staging showed intense focal FDG uptake in the endometrium suggesting endometrial malignancy. PET/CT showed multiple node uptakes in the pericaval region, paraaortic region, common iliac, and both internal iliac and external iliac regions suggesting multiple pelvic and retroperitoneal node metastases. MRI showed multiple metastatic lymphadenopathy in the retroperitoneum and pelvic cavity. Pathologic diagnosis performed with dissected pelvic and paraaortic nodes was confirmed as a follicular malignant lymphoma positive for B–cell lymphoma-2(Bcl-2) stain, not the metastatic node of primary endometrioid carcinoma.     

Extraordinarily high F-18 FDG uptake caused by radiation necrosis in a patient with nasopharyngeal carcinoma

A false-positive F-18 FDG PET scan caused by osteoradionecrosis and inflammation in patients with nasopharyngeal carcinoma (NPC) has been reported. The standard uptake values (SUVs) in these false-positive cases are always below 6 and decrease with time. This report is concerned with a false-positive result with extraordinarily high F-18 FDG uptake, which increased on the delayed 3-hour image. A 63-year-old man with NPC underwent surgical removal and radiotherapy (7400 cGy) in July 2003. In October 2003, the CT scan showed a large soft tissue mass over the nasopharynx. Tumor recurrence was suspected. F-18 FDG PET scan showed an FDG-avid lesion over the nasopharyngeal region with a maximum SUV of 28.8 at 1 hour that increased to 30.4 at 3 hours. Biopsy was performed and the histopathologic examination showed only necrotic tissue and no evidence of tumor cells. Radiation necrosis was diagnosed. No evidence of tumor recurrence was noted during the 10-month follow-up period.     

¹¹C-choline and F-18 FDG PET/CT images of hemangioblastoma

We present the F-18 FDG and 11C-choline PET/CT images obtained in 2 cases of hemangioblastoma. Hemangioblastoma is a highly vascular benign tumor that typically arises in the cerebellum or spine. The characteristic findings of a hemangioblastoma on both CT and MR include a peripherally located cerebellar lesion with a central cystic region and a peripherally enhanced nodule. In both patients, the uptake in the lesion was relatively low on the F-18 FDG PET/CT images and relatively high on the 11C-choline PET/CT images.     

The clinical usefulness of F-18 FDG coincidence PET without attenuation correction and without whole-body scanning mode in pulmonary lesions comparison with CT, MRI, and clinical findings

PURPOSE: This study was undertaken to assess the clinical usefulness of fluorine-18 flurodeoxyglucose (F-18 FDG) coincidence detection (CoDe) positron emission tomography (PET) of various lung lesions by comparing it with CT, MRI, and clinical findings. MATERIALS AND METHODS: Forty-two patients with pulmonary lesions underwent CoDe PET using a dual-head gamma camera equipped with a 5/8 inch thick NaI (Tl) crystals. The patients were prepared for the study by overnight fasting. Data was acquired at approximately 1 hour after the intravenous injection of 111 to 370 MBq (3 to 10 mCi) of F-18 FDG. A spinal scan of the thorax was performed using a slip ring gantry for 30 minutes. After rebinning, routine tomographic slices were reconstructed without attenuation correction and the images were analyzed visually. RESULTS: Pathologic diagnoses and staging were obtained at surgery in nine patients; in the remaining 33 patients, aspiration cytology was available. CoDe PET detected all 35 pathologically proved malignant lesions. In nine patients who underwent surgery, seven CoDe PET studies corresponded with pathologic staging, whereas in six of the nine patients, CT and MRI corresponded with the pathologic findings. Seven patients also had benign lesions that showed FDG uptake. CONCLUSIONS: F-18 FDG CoDe PET was sensitive in the evaluation of lung lesions but was not specific for malignancy. F-18 FDG CoDe PET was more sensitive than CT and MRI in nodal staging in the limited number of patients studied thus far.     

Peritoneal tuberculosis with elevated serum CA125 mimicking peritoneal carcinomatosis on F-18 FDG-PET/CT

18F-fluorodeoxyglucose positron emission tomography (F-18 FDG-PET) plays an important role in differentiating benign from malignant tumors. However, some false-positive findings, such as tuberculosis, may occur. We report a case referred for F-18 FDG whole-body PET computed tomography (PET/CT) scan owing to an elevated serum cancer antigen 125 (CA125). An FDG-PET/CT scan showed multiple hypermetabolic foci in the mesentery and peritoneum with further increase of FDG uptake on the delayed scan, mimicking peritoneal carcinomatosis. Subsequent laparoscopic biopsy showed granulomatous inflammation, and tuberculosis polymerase chain reaction showed a positive result. Serum CA125 returned to normal following treatment with anti-tuberculosis drugs. Peritoneal tuberculosis should be considered as a differential diagnosis in a tuberculosis endemic region.     

Role of F-18 FDG PET/CT in assessing bone marrow involvement in pediatric Hodgkin’s lymphoma

Objectives

The aim of the current study was to assess the utility of F-18-fluoro-2-deoxy-d-glucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) in assessing bone marrow involvement (BMI) compared to bone marrow biopsy (BMB) in initial staging of Hodgkin’s lymphoma (HL) in pediatric patients.

Methods

Data of 38 pediatric patients (mean age 9.8 years, range 3–18 years) with HL were analyzed for the involvement of bone marrow. All patients underwent non-contrast F-18 FDG PET/CT study. BMB was done in 31 patients from the bilateral iliac crests. Scans were interpreted by two nuclear medicine physicians blinded to the details of BMB.

Results

Of the 31 patients who underwent BMB, 5 patients had lymphomatous involvement on BMB. PET/CT was positive in four of these five patients. In 26 patients negative on BMB, PET was negative in 23 patients and positive in 3 patients for BMI. The sensitivity and negative predictive value of F-18 FDG PET/CT was 87.5 and 96 %, respectively, for BMI.

Conclusions

F-18 FDG PET/CT can predict BMB results with high accuracy. F-18 FDG PET/CT may be used at initial staging of pediatric Hodgkin’s lymphoma as it uncovers unsuspected BMI and BMB may be omitted in patients with PET-positive BMI.     

FDG PET evaluation of residual masses and regrowth of abdominal lymph node metastases from colon cancer compared with CT during chemotherapy.

Fluorine-18-2-deoxy-2-fluoro-D-glucose (F-18 FDG) PET may be more suitable for follow-up after cancer treatment than other morphologic approaches, because it reflects tumor viability. A patient with abdominal lymph node metastases from colon cancer was followed by CT and F-18 FDG PET during chemotherapy. F-18 FDG PET tumor images changed in accordance with the clinical progress, whereas CT findings were relatively unchanged. This case clearly shows the utility of F-18 FDG PET for follow-up during cancer chemotherapy.     

Malignant epithelioid hemangioendothelioma of the lower extremity: staging with F-18 FDG PET/CT

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.     

磷酸盐尿性间叶肿瘤的临床特点及其综合影像学表现

目的 探讨磷酸盐尿性间叶肿瘤（PMT）的临床特点及其综合影像学表现。 方法 回顾性分析2014年3月至2018年11月于上海交通大学附属第六人民医院经组织病理学检查确诊的38例PMT患者（其中男性22例、女性16例,年龄8~72岁, 中位年龄45.5岁）的临床资料,以及超声、CT、MRI、99Tcm-联肼尼克酰胺-酪氨酸3-奥曲肽（99Tcm-HYNIC-TOC）SPECT/CT、99Tcm-亚甲基二膦酸盐（99Tcm-MDP）SPECT/CT骨显像和18F-氟脱氧葡萄糖（FDG）PET/CT的影像学表现,分析并总结PMT的临床特点及其综合影像学表现。 结果 PMT患者的临床症状主要表现为进行性全身骨痛、肌肉无力以及肿瘤原发部位局部不适等;术前患者的血液生化检查结果显示血磷水平降低。38例患者中,有超声、CT、MRI、99Tcm-HYNIC-TOC SPECT/CT、99Tcm-MDP SPECT/CT骨显像和18F-FDG PET/CT显像资料者分别为8、20、18、12、8、7例。PMT患者的超声图像表现为肿瘤内低或混合回声,血流信号丰富。50.0%（4/8）骨组织来源的PMT患者在CT上表现为溶骨性病变;软组织来源的12例PMT患者在CT上表现为异常软组织密度灶或软组织肿块。PMT患者的病灶在 MRI上均表现为T1加权像等低信号、T2加权像高低混杂信号,增强MRI表现为肿瘤实性部分明显强化。PMT患者99Tcm-HYNIC-TOC SPECT/CT显像阳性率为83.3%（10/12）。PMT患者99Tcm-MDP SPECT/CT骨显像均呈多发异常骨代谢活跃灶,其中1例软组织来源的肿瘤显示为病灶放射性摄取轻度增高。PMT患者18F-FDG PET/CT显像中所有病灶的葡萄糖代谢均增高,最大标准化摄取值为3.1~10.7,中位数为4.0。 结论 PMT的临床特点主要表现为肿瘤导致的低磷性骨软化,而原发肿瘤的表现不突出;影像学表现没有特异性,99Tcm-HYNIC-TOC SPECT/CT、99Tcm-MDP SPECT/CT骨显像及18F-FDG PET/CT检查可能有助于临床对PMT进行准确地定位并评估患者的全身情况。     

A Case of Acute Q Fever Hepatitis Diagnosed by F-18 FDG PET/CT

A 53-year-old man with fever of unknown origin underwent F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) as a workup for a fever of unknown origin. On presentation, he complained of fever, chills, and myalgia. The F-18 FDG PET/CT scan showed diffusely increased uptake of the liver with mild hepatomegaly. A liver biopsy then revealed fibrin-ring granulomas typically seen in Q fever. The patient was later serologically diagnosed as having acute Q fever as the titers for C. burnetii IgM and IgG were 64:1 and 16:1, respectively. He recovered completely following administration of doxycycline. This indicates that F-18 FDG PET/CT may be helpful for identifying hepatic involvement in Q fever as a cause of fever of unknown origin.     

Hypermetabolism of Skeletal Muscles Following Sexual Activity: A Normal Variation

A 46-year-old man with early gastric cancer at the gastric antrum underwent an F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)-computer tomography (CT) scan for staging. No definite abnormal FDG uptake of the stomach was shown. Incidentally, variable FDG uptake at the bilateral serratus muscles, abdominal muscles and muscles of both thighs (Fig. 1) was observed. He had no significant past medical history except recently diagnosed stomach cancer. On personal interview, he described having had sexual activity the night before the F-18 FDG PET/CT scan, although he was aware of needing to avoid physical activity before a PET scan. The F-18 FDG PET/CT scan was done at 2:00 p.m. Therefore, the hypermetabolism of individual skeletal muscles following sexual activity lasted over 12 h. This case illustrates the hypermetabolism of skeletal muscles following sexual activity as a normal variation.Open in a separate windowFig. 1A 46-year-old man with early gastric cancer at the gastric antrum underwent a F-18 fluorodeoxyglucose (FDG) PET/CT scan for staging. The patient had been fasting for over 6 h, and his blood sugar level was within normal limits at the time of injection. After intravenous injection of 431 MBq F-18 FDG, the patient rested in the supine position for 1 h on a bed. The F-18 FDG PET/CT was acquired 60 min after the injection. The PET/CT scan was done at 2:00 p.m. He had had sexual activity the night before the F-18 FDG PET/CT scan. The MIP image of the F-18 FDG PET (a) shows diffuse and moderate hypermetabolism of the bilateral serratus muscles, bilateral rectus abdominis muscles, left psoas muscle and bilateral adductor muscles. The PET-CT fusion image of the transverse plane (b) and the coronal plane (c) shows diffuse increased uptake of F-18 FDG at bilateral serratus muscles (straight arrows, →, 4.5 and 3.0), bilateral rectus abdominis muscles (arrowheads, ►, 5.5), left psoas muscle (dotted arrow, , 4.0), left iliacus muscle (curved arrow, , 3.3), bilateral pectineus muscles (double arrow heads, , 6.0), bilateral adductor brevis muscles (open arrow, , 5.3) and bilateral adductor longus (solid arrow, , 6.8). The maximum standardized uptake value (SUV) of the individual muscles is in parentheses     

Growing Cardiac Hemangioma on Serial F-18 FDG PET/CT

Cardiac hemangiomas are extremely rare, benign tumors, which can occur anywhere in the heart. Symptoms are variable according to the size, extension and tumor location, but most cases are asymptomatic and are detected incidentally. They may grow, remain stable and regress; therefore, the natural course of the tumors is unpredictable. Diagnosis mainly depends upon echocardiography, CT, MRI and angiography. Reports of detection by F-18 FDG PET/CT are very limited. We report a case of cardiac hemangioma attached to the right ventricle, compressing the ventricle. It was revealed incidentally on F-18 FDG PET/CT for routine evaluation of thyroid cancer. During two serial F-18 FDG PET/CTs, it grew from 2.8 cm to 4.0 cm with mild FDG uptake. After surgery, the patient remained stable without any complications.     

Myelofibrosis on F-18 FDG PET Imaging

A 60-year-old male was referred for a positron emission tomography (PET) scan using F-18 fluoro-2-deoxyglucose (F-18 FDG) for evaluation of a right lung opacity identified on a computed tomography (CT) scan. The patient also had a history of idiopathic myelofibrosis. The PET scan revealed markedly increased uptake throughout the spleen and liver, which were massively enlarged. There was also significantly increased uptake diffusely throughout the bone marrow. These findings are a reflection of the patient's myelofibrosis.