Ari Chong

Changes in 18F-Fluorodeoxyglucose Uptake in the Spinal Cord in a Healthy Population on Serial Positron Emission Tomography/Computed Tomography

We aimed to determine the changes in 18F-fluorodeoxyglucose (FDG) uptake in the spinal cord on two serial positron emission tomography/computed tomography (PET/CT) scans in a healthy population. We retrospectively enrolled healthy people who underwent PET/CT twice for cancer screening. We excluded those who had degenerative vertebral disease, neurologic disease, or a history of a vertebral operation. The standardized uptake value (SUVmax) of the spinal cord of each mid-vertebral body was obtained by drawing a region of interest on an axial image of PET/CT. For analysis, the cord-to-background ratio (CTB) was used (CTB=SUVmax of each level/SUVmax of L5 level). Differences in pattern, sex, age, and intervals of the two serial PET/CT scans were analyzed. A total of 60 PET/CT images of 30 people were analyzed. The mean interval between the two PET/CT imaging studies was 2.80±0.94 years. On the follow-up PET/CT, significant change was shown only at the level of the C6 and T10 vertebrae (p<0.005). Mean CTB showed a decreasing pattern from cervical to lumbar vertebrae. There were two peaks at the lower cervical level (C4-6) and at the lower thoracic level (T12). Neither sex nor age significantly affected CTB. The FDG uptake of the spinal cord changed significantly on follow-up PET/CT only at the level of the C6 and T10 vertebrae. This finding is valuable as a baseline reference in the follow-up of metabolic changes in the spinal cord.

Clinical Usefulness of 18F-FDG PET/CT in the Detection of Early Recurrence in Treated Cervical Cancer Patients with Unexplained Elevation of Serum Tumor Markers

We investigated the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for restaging of treated uterine cervix squamous cell cancer with tumor maker elevation that was not explained by other conventional evaluation. We enrolled 32 cases who underwent PET/CT for the restaging of treated cervical cancer with tumor marker elevation that was not explained by recent conventional evaluation. All enrolled cases had squamous cell carcinoma. Increased tumor markers included squamous cell carcinoma antigen (SCC Ag) and carcinoembryonic antigen (CEA). PET/CT findings were determined by pathologic confirmation or clinical follow-up. We compared PET/CT accuracy and clinical parameters including normalization of tumor markers in both the SCC Ag elevation group and the CEA elevation group. The sensitivity, specificity, positive predictive value, and negative predictive value of PET/CT in detecting recurrence were 100%, 83.3%, 82.4%, and 100%, respectively. Accuracy was significantly different between the SCC Ag elevation group and the CEA elevation group (p=0.0169). PET/CT with SCC Ag elevation was more accurate (100%) than PET/CT with CEA elevation (66.7%). Normalization of tumor markers was observed more often in the SCC Ag elevation group than in the CEA elevation group (p=0.0429). PET/CT showed high negative predictive value and sensitivity in the restaging of cervical cancer with unexplained tumor marker elevation. PET/CT was more accurate in patients with SCC Ag elevation than in those with CEA elevation.

Gelatinous degeneration of the bone marrow mimicking osseous metastasis on 18F-FDG PET/CT.

Gelatinous degeneration of the bone marrow is rare, and its pathogenesis is unknown. A 61-year-old man with rectal cancer, who was treated successfully with surgery and chemotherapy 1 year ago, underwent 18F-FDG PET/CT for restaging, which showed a focal hot spot in the left scapula mimicking osseous metastasis. Excision bone biopsy revealed gelatinous degeneration of the bone marrow.

Variations in findings on 18F-FDG PET/CT, Tc-99m HDP bone scan and WBC scan in chronic multifocal osteomyelitis

Dear Editor, Chronic recurrent multifocal osteomyelitis (CRMO) is a rare condition the true incidence of which is unknown. CRMO is associated with several autoimmune diseases, including inflammatory bowel diseases, such as ulcerative colitis (as in the patient in this study), Wegener’s granulomatosis and psoriasis. In addition, CRMO has been reported to be associated with a pediatric variant of SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome. CRMO may be solitary ormultifocal. The diagnosis of CRMO is based on clinical symptoms, scans and pathologic findings. Until now, there have been no reports of the results of white blood cell (WBC) scans in CRMO. This is a case study of a patient with CRMO who underwent Tc-99m hydroxymethylene diphosphonate (HDP) bone scan, Tc-99m hexamethylpropyleneamine oxime (HMPAO)WBC scan and F-18 fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomo-graphy (F-FDG PET/CT), and showed different scan findings with each lesion with different degrees of inflammation. A 41-year-old man with known ulcerative colitis and an abscess on the right zygoma underwent a Tc-99m HDP bone scan for pain in the lower back, right knee, left ankle, left anterior chest wall and sternum. An anterior view of the Tc-99m HDP bone scan (Fig. 1a) showed hot uptakes not only in the lesions associated with pain (right zygmotic bone, sternum, right patella, left third rib, spinous process of T11) but also in the lesions without pain (skull and right cuboid bone). However, the Tc-99m HMPAO WBC scan (Fig. 1b) was negative for all lesions. The F-18 FDG PET/CT (Fig. 1c, maximum intensity projection [MIP]; d, lateral MIP; e, sagittal image of CT portion; f, sagittal image of PET portion) showed hypermetabolism only in the sternum and T11–L2 vertebrae. Note that the sternum (blank arrow in Fig. 1a,c,d) showed hot uptake and hypermetabolism on the bone scan and the PET/CT but not on the WBC scan. Also note that spinal processes of vertebrae showed hypermetabolism in much broader lesions on the PET/CT (white arrow in Fig. 1d,f) than on the bone scan (arrow in Fig. 1e). A biopsy of the sternum of this patient was done; acute and chronic inflammation with edematous soft tissue change was revealed on microscopy. The diagnosis of CRMO was thus confirmed. In this patient, the discrepancy between the findings of the WBC scan and the F-18 FDG PET/CT in the vertebrae and sternum might be due to the ‘chronicity’ of the inflammation. In WBC scans, false-negatives are known to occur with chronic infection. In addition, this patient was taking antibiotics at the time of the WBC scan. The antibiotics might alter leukocyte function in this patient as well. Among the three scans (bone scan, WBC scan and F-18 FDG PET/CT), the bone scan showed greatest numbers of lesions. It has been previously reported that a bone scan is able to detect many asymptomatic lesions (even radiographically obscure foci of the disease). However, not only can a bone scan be positive in active disease, it can also be positive where there are recovering lesions. Otherwise, the FDG PET is highly effective in excluding osteomyelitis, according to Zhuang et al. FDG uptake is not the same thing as bone turn-over, which is shown by a bone scan. In this patient, bone scan-positive and FDG PET/CT-negative lesions (skull and right cuboid bone) were asymptomatic both initially and after 18 months of follow-up, suggesting they were recovering lesions. This might account for the discrepancy in findings between the bone scan and the F-18 FDG PET/CT in this case. Based on the scan findings in this case and other previous reports, it would be helpful to have a bone scan performed in the beginning of evaluation of CRMO to detect all lesions, followed by F-18 FDG PET/ CT to detect only active lesions.

Inflammatory Myofibroblastic Tumor Mimicking Gastric Gastrointestinal Stromal Tumor on 18f-fdg Pet/ct

A 59-year-old man underwent abdominal CT for evaluation of weight loss and generalized weakness. A large mass protruding from the lesser curvature of the stomach suggestive of gastrointestinal stromal tumor was demonstrated. F-FDG PET/CT showed hypermetabolic activity in the gastric mass. Mass excision and wedge resection were performed, and the diagnosis of inflammatory myofibroblastic tumor was confirmed.