Lung Adenocarcinoma Staged as an Unknown Primary Presenting with Symptomatic Colon Metastases: Staging by 18F-FDG PET/CT

A 66-year-old man, who presented with bright red blood per rectum, was referred for an ¹⁸F-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 ¹⁸F-FDG PET/CT in staging a patient who presented with symptomatic colon metastases of an unknown primary lung malignancy.     

Evaluation of Adrenal Masses in Lung Cancer Patients Using F-18 FDG PET/CT

Purpose

The aim of this study was to assess the diagnostic efficacy of PET/CT using various parameters for the characterization of adrenal nodules in lung cancer patients.

Methods

Sixty-one adrenal nodules in 51 lung cancer patients were evaluated. The final diagnosis was based on histology (n = 2) or imaging follow-up (n = 59, range of follow-up: 7–57 months, median 27 months). Each adrenal nodule was analyzed using four parameters of PET/CT: the maximum standardized uptake value (SUV_max), the adrenal nodule/liver ratio of the SUV (SUV ratio), Hounsfield units (HU) and size. The optimal cutoff of each parameter for the identification of metastatic nodule was determined by ROC analysis and then the diagnostic efficacy was compared among the parameters.

Results

Of the 61 adrenal nodules, 45 (73%) were considered metastasis. The optimal cutoff values of the parameters were SUV_max >2.7, SUV ratio >1.3, HU >18 and size >20 mm, respectively. The sensitivity, specificity and accuracy by SUV_max >2.7 were 88.9%, 87.5% and 88.5%, and those by SUV ratio >1.3 were 84.4%, 100% and 88.5%, respectively. The combination of SUV ratio >1.3 and HU >18 had sensitivity of 97.7%, specificity of 81.2% and accuracy of 93.4% to predict adrenal metastasis in patients with lung cancer.

Conclusion

SUV ratio from F-18 FDG PET/CT could identify the adrenal metastasis in lung cancer patients. The combination of SUV ratio and HU can improve the accuracy of differentiating benign and metastatic adrenal lesions in lung cancer patients.     

F-18 FDG PET/CT imaging of low-grade mucoepidermoid carcinoma of the bronchus

Mucoepidermoid carcinomas in the bronchial tree are extremely rare tumors. Such tumors are classified into low-grade and high-grade on the basis of histological criteria. Fluorine-18-fluorodeoxyglucose positron emission tomography (F-18 FDG PET) is a useful technique for the evaluation of pulmonary lesions; however, to our knowledge, F-18 FDG PET findings in mucoepidermoid carcinoma of the bronchus have been described in only a few cases. Identifiable focal F-18 FDG uptake has been reported in high-grade mucoepidermoid carcinoma, but it is unclear whether F-18 FDG accumulates in low-grade mucoepidermoid carcinoma. Here, we present the case of a 37-year-old woman, with pathologically proven low-grade mucoepidermoid carcinoma, who underwent high-resolution computed tomography (CT) and F-18 FDG PET/CT before treatment.     

Multiple Skeletal Muscle Metastases in a Case of Transitional Cell Carcinoma of Bladder Detected by F-18 FDG PET/CT

We present a case of poorly differentiated muscle invasive transitional cell carcinoma in a 64-year-old male diagnosed with FDG-avid mass in the urinary bladder wall and multiple skeletal muscles visualised on F-18 FDG PET/CT.     

Uterine Epithelioid Angiosarcoma on F-18 FDG PET/CT

Uterine epithelioid angiosarcoma can have conventional imaging characteristics similar to those of other uterine tumors, such as leiomyoma, leiomyosarcomas or hemangioendothelioma. Uterine epithelioid angiosarcoma exhibiting increased fluorine-18 fluorodeoxyglucose (F-18 FDG) activity can be misdiagnosed. A 61-year-old woman who was diagnosed with uterine epithelioid angiosarcoma underwent F-18 FDG positron emission tomography/computed tomography (PET/CT) as a part of the pretreatment work up for surgery. F-18 FDG PET/CT showed an intense F-18 FDG uptake in the uterus in addition to increased F-18 FDG uptake at the paraaortic and aortocaval lymph nodes. To our knowledge, this is the first case report of intense F-18 FDG uptake in uterine epithelioid angiosarcoma in Korea.     

Uterine Intravenous Leiomyomatosis with Intracardiac Extension and Pulmonary Benign Metastases on FDG PET/CT: A Case Report

A 48-year-old woman presented with a 50-day history of irregular vaginal bleeding and lower abdominal pain. Ultrasound indicated an extremely large occupying lesion in the pelvic cavity that was highly suggestive of malignancy. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) was performed to further assess the nature of pelvic abnormality. PET/CT images demonstrated a diffusely lobulated mass ranging from cervix up to the inferior pole of kidneys with mild FDG uptake. Simultaneously, multiple nodules in bilateral lungs and a hypodense lesion in the right ventricle were shown without FDG-avidity. Based on the imaging results, the presumptive diagnosis was uterine intravenous leiomyomatosis with intracardiac extension and pulmonary benign metastases, which was subsequently confirmed by MRI and the lesion biopsy.     

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.     

Peritoneal Lymphomatosis Imaged by F-18 FDG PET/CT

Peritoneal lymphomatosis is uncommon, but when encountered is associated with aggressive histological subtypes of high-grade lymphoma, such as small-cell, large-cell, mixed large and small cell, non-cleaved, lymphoblastic Burkitt-like, and diffuse large B cell lymphomas. The CT findings of peritoneal lymphomatosis are linear or nodular peritoneal thickening, retroperitoneal lymphadenopathy, omental and mesenteric involvement with streak-like infiltrations or a bulky mass, bowel wall thickening, hepatosplenomegaly, and ascites. The authors report the first FDG PET/CT images of diffuse large B-cell lymphoma of small bowel origin associated with peritoneal lymphomatosis in a 69-year-old man. The lesions demonstrated intense FDG uptake in PET/CT images.     

Giant Cell Tumor Pulmonary Metastases Mimic Primary Malignant Pulmonary Nodules on 18F-FDG PET/CT

A 59-year-old man with a 30-year history of multiple recurrences of a giant cell tumor (GCT) of the left knee was referred for an ¹⁸F-FDG PET/CT to evaluate a solitary pulmonary nodule. The nodule was mildly FDG-avid, raising suspicion of malignancy. It was excised and histologically proven to be a GCT pulmonary metastasis. A follow-up PET/CT done 2 years later revealed a new, larger lung mass that was more intensely FDG-avid, but of the same histology. This rare report highlights a pitfall in the evaluation of solitary pulmonary lesions by ¹⁸F-FDG PET/CT in patients with GCT of the bone.     

Detection of Thyroid Metastasis of Renal Transitional Cell Carcinoma Using FDG PET/CT

A 69-year-old man who was diagnosed with renal transitional cell carcinoma (TCC) underwent F-18 fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET/CT) for detecting recurrence after chemotherapy. FDG PET/CT revealed multiple new hypermetabolic lesions in many places, including the right thyroid gland. Biopsy of the thyroid lesion was performed, and a diagnosis of metastatic TCC was made. We could detect thyroid metastasis of renal TCC by FDG PET/CT.     

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.     

Monitoring Therapeutic Response in a Case of Extrapulmonary Tuberculosis by Serial F-18 FDG PET/CT

Due to the low yield of AFB smear and culture in extrapulmonary tuberculosis, therapeutic responses of patients with extrapulmonary tuberculosis are usually monitored clinically and/or radiographically. Such monitoring techniques, however, are not enough to provide effective diagnosis if a remnant lesion exists after treatment. Tuberculosis presents hypermetabolic activity on F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) scanning. Reported herein is a case of extrapulmonary tuberculosis where the therapeutic response was assessed via serial F-18 FDG PET/CT scanning, which was useful for detecting the extent of extrapulmonary tuberculosis and for estimating the patient’s therapeutic response.     

Benign Schwannoma Mimicking Metastatic Lesion on F-18 FDG PET/CT in Differentiated Thyroid Cancer

We report a case of benign schwannoma mimicking metastatic carcinoma. A 55-year-old female with papillary thyroid carcinoma underwent total thyroidectomy. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) demonstrated a focal hypermetabolic lesion with maximum standardized uptake value (SUVmax) 5.3 at the right chest wall. Conventional chest CT demonstrated a 5.4 cm ovoid mass lesion between the intercostal muscles and liver. Pathology revealed a schwannoma by tumor excision. This case demonstrates that benign schwannoma may demonstrate FDG uptake mimicking metastatic carcinoma.     

Incidental Finding of Appendiceal Adenocarcinoma in F-18 FDG PET/CT for Health Screening

F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) that simultaneously offers anatomic and metabolic information is widely used and has become an effective modality in many clinical fields, especially oncology, and also may detect an unexpected primary cancer. Appendiceal carcinoma is relatively uncommon and not associated with characteristic symptoms. We report the case of a 53-year-old man with appendiceal adenocarcinoma, who had only mild fever. The tumor was detected early on F-18 FDG PET/CT for health screening.     

Tenosynovial Giant Cell Tumor of Diffuse Type Mimicking Bony Metastasis Detected on F-18 FDG PET/CT

Tenosynovial giant cell tumor of diffuse type (TGCT-D) is a locally aggressive neoplasm that arises in the tendon sheath, bursa, or synovium. It typically involves the appendicular skeleton and rarely involves the axial skeleton. Because there are no specific findings of TGCT-D based on imaging studies or clinical symptoms, TGCT-D can be confused with other primary or metastatic bone tumors. We report findings of TGCT-D involving the T9 vertebra incidentally detected on F-18 FDG PET/CT in a patient with papillary thyroid cancer.     

Usefulness of F-18 FDG PET/CT in the Evaluation of Early Treatment Response After Interventional Therapy for Hepatocellular Carcinoma

Purpose

This retrospective study investigated the usefulness of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) after interventional therapy for hepatocellular carcinoma (HCC).

Methods

Between March 2007 and November 2010, 31 patients (24 men, 7 women; mean age, 61.8 ± 11.0 years) with 45 lesions underwent PET/CT within 1 month after interventional therapy for HCC. Twenty-six patients with 40 lesions underwent transcatheter arterial chemoembolization (TACE), two patients with 2 lesions underwent radiofrequency ablation (RFA), and three patients with 3 lesions underwent percutaneous ethanol injection therapy (PEIT). Patients with a history of previous interventional therapy were excluded. Visual analysis was graded as positive when FDG was observed as an eccentric, nodular, or infiltrative pattern, and negative in case of isometabolic, hypometabolic, or rim-shaped uptake. For quantitative analysis, the standardized uptake value (SUV) was measured by region of interest technique. Maximum SUV (SUVmax) was assessed, and the ratio of SUVmax of tumor to mean SUV of normal liver (TNR) was calculated. The patients were divided into two groups, with and without residual tumor, based on 6-month clinical follow-up with serum alpha-fetoprotein and contrast-enhanced abdominal CT.

Results

Of the 45 lesions, 24 were classified in the residual tumor group and the other 21 lesions in the no residual tumor group. No residual tumor was detected after RFA or PEIT. By visual analysis, the respective values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.5, 71.4, 77.8, 83.3, and 80.0 %. However, there were no significant differences in the SUVmax and TNR between the two groups.

Conclusions

It is suggested that FDG PET/CT may play a role in the evaluation of early treatment response after interventional therapy for HCC. The results indicate that FDG PET/CT visual analysis may be more useful than quantitative analysis. Further prospective studies with a large number of patients and established protocol are needed to substantiate our results.     

Bone metastasis in patients with non-small cell lung cancer: The diagnostic role of F-18 FDG PET/CT

Purpose

To evaluate the performance of F-18 FDG PET/CT in the detection of bone metastasis in non-small cell lung cancer (NSCLC) patients.

Materials and methods

Three hundred and sixty-two consecutive NSCLC patients who underwent F-18 FDG PET/CT scanning were retrospectively analyzed. Each image of PET/CT, combined CT, and PET was performed at 10 separate areas and interpreted blindly and separately. The sensitivity, specificity and accuracy of F-18 FDG PET/CT, combined CT and F-18 FDG PET were calculated and the results were statistically analyzed.

Results

Bone metastasis was confirmed in 82 patients with 331 positive segments based on the image findings and clinical follow-up. On patient-based analysis, the sensitivity of F-18 FDG PET/CT (93.9%) was significantly higher than those of combined CT (74.4%) and F-18 FDG PET (84.1%), respectively (p < 0.05). The overall specificity and accuracy of combined CT, F-18 FDG PET, and F-18 FDG PET/CT were 90.7%, 93.2%, 98.9% and 87.0%, 91.2%, and 97.8%, respectively (compared with PET/CT, p < 0.05). On segment-based analysis, the sensitivity of the three modalities were 79.5%, 94.3%, and 98.8%, respectively (compared with PET/CT, p < 0.05). The overall specificity and accuracy of the three modalities were 87.9%, 89.2%, 98.6% and 84.5%, 91.2%, 98.7%, respectively (compared with PET/CT, p < 0.05).

Conclusion

F-18 FDG PET/CT is superior to F-18 FDG PET or combined CT in detecting bone metastasis of NSCLC patients because of the complementation of CT and PET. It is worth noting that the added value of F-18 FDG PET/CT may beneficially impact the clinical management of NSCLC.     

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.     

Rosai-Dorfman Disease: Importance of 18F FDG PET/CT to Determine Extension and Extranodal Involvement

Rosai-Dorfman disease or sinus histiocytosis with lymphadenopathy is a rare benign histiocytic proliferative disorder of unknown etiology first described in 1969. It typically affects older females and most common presentation is with massive lymphadenopathy and nonspecific systemic symptoms; therefore, it is often confused with lymphoproliferative disorders [1, 2]. We present the case of a 69-year-old woman with nasal obstruction as only complaint. Laboratory tests showed normal leukocyte count with elevated ANC (absolute neutrophil count), normal RBC count with normal MCV (mean corpuscular volume) and MCH (mean corpuscular hemoglobin), elevated ESR (erythrocyte sedimentation rate), and normal IgG, IgA, and IgM values. Evaluation revealed a nasopharyngeal mass, which was biopsied and reported emperipolesis with positive CD68 and S-100; typical and differential findings of this disease [1, 2]. ¹⁸F FDG PET/CT was performed to determine the extent and involvement of the disease. Considering the presence of few symptoms and no significant laboratory abnormality, treating physicians decided to start a regimen of corticosteroids (prednisolone) for a period of 4 months, after which a follow-up with ¹⁸F FDG PET/CT will be performed.     

F-18 FDG PET/CT findings in postradiation pelvic insufficiency fracture

We retrospectively identified eight patients who underwent F-18 FDG PET/CT and had diagnostic findings of postradiation pelvic insufficiency fracture. The fractures had a median SUV_max of 2.5 (range, 1.6 to 6.0) and were initially interpreted as possible metastases in six patients. A new bone lesion developing in the sacrum, pubic ramus, or acetabulum after radiation for pelvic malignancy is likely to be a postradiation pelvic insufficiency fracture, even if associated with increased FDG uptake at PET.