Radiation Myelopathy Visualized as Increased FDG Uptake on Positron Emission Tomography

Extensive Intraspinal Hypermetabolism Caused by Neurobrucellosis Shown on 18F-FDG PET/CT

A 55-year-old man and a 52-year-old man presenting with neurological symptoms were referred for F-FDG PET/CT for the underlying malignancy. In both cases, extensive intraspinal hypermetabolism was observed in F-FDG PET/CT. The cerebrospinal fluid culture finally confirmed infection of Brucella. This report illustrates that neurobrucellosis may present as intraspinal hypermetabolism on F-FDG PET/CT, and thus it should be added to the differential diagnosis.

Solitary Acute Inflammatory Demyelinating Lesion of the Cervical Spinal Cord Mimicking Malignancy on FDG PET/CT

A 43-year-old woman presented with numbness of the left hand and leg for 4 weeks. MRI of the spinal cord revealed an intramedullary lesion with central nodular enhancement at the C3 level. Primary tumor or metastasis of the cervical spinal cord was suspected. FDG PET/CT showed focal hypermetabolism of the spinal cord corresponding to the gadolinium-enhanced nodule. The patient underwent resection of the cervical spinal cord lesion. Histopathological findings of the resected specimens were consistent with acute inflammatory demyelinating lesion.

A Large Cohort Study of 18F Fluoro-Deoxy-Glucose Uptake in Normal Spinal Cord: Quantitative Assessment of the Contamination From Adjacent Vertebral Marrow Uptake and Validity of Normalizing the Cord Uptake Against the Lumbar Thecal Sac

PURPOSE

This study aimed (1) to assess the influence of age, sex, blood glucose, and body mass index on the F fluoro-deoxy-glucose (F-FDG) uptake in normal spinal cord; (2) to quantitatively evaluate contamination of the spinal cord SUVmax by the adjacent vertebral marrow activity; and (3) to investigate the validity of normalizing spinal cord SUVmax against lumbar thecal sac SUVmax.

METHODS

Two hundred positron emission tomography-computed tomography examinations of subjects with normal spinal cord were retrospectively reviewed. SUVmax of spinal cord and vertebral body was obtained at C2, C5, T6, T12, and L3 levels. Pearson correlation coefficients (r) were obtained at each level between spinal cord SUVmax and vertebral marrow SUVmax, age, body mass index, and blood glucose. Cord to background ratio (CTB) was calculated as the ratio between SUVmax of spinal cord and SUVmax of L3 thecal sac. The coefficient of variation (CV) of spinal cord SUVmax was compared with the CV of CTB.

RESULTS

Spinal cord SUVmax was highest at C2 (mean, 1.76) and lowest at T6 (mean, 1.37) with SD of 0.32 to 0.36 SUV. Sex (P > 0.45), age (r: -0.25 to -0.06), body mass index (r: 0.19 to 0.27), and blood glucose (r: -0.17 to 0.22) had no impact on the spinal cord SUVmax. A moderate to strong positive correlation (r: 0.66-0.80) was found between spinal cord SUVmax and the corresponding vertebral marrow SUVmax. The CV of CTB was greater (0.28-0.32) than the CV of spinal cord SUVmax (0.19-0.25) across all levels.

CONCLUSIONS

Of the variables studied, only contamination from adjacent vertebral marrow activity significantly affected the SUVmax of spinal cord. This contamination should be corrected for when reporting spinal cord FDG uptake. Lumbar thecal sac is not a valid reference for normalizing spinal cord FDG uptake.

(18)F-FDG uptake of the spinal cord was decreased after conventional dose radiotherapy in esophageal cancer patients

OBJECTIVE

We retrospectively investigated changes of (18)F-fluorodeocyglucose ((18)F-FDG) uptake in the spinal cord, inside and outside the radiation fields, in patients with esophageal cancer before and after conventional dose radiotherapy.

METHODS

A total of 17 consecutive patients with esophageal cancer (16 males, one female; age 50-83 years, mean 67.0 years), who underwent conventional dose radiotherapy and (18)F-FDG PET/CT before and 5.1 months (range 1.6-8.6 months) after the radiotherapy, were retrospectively evaluated. Sixteen patients had esophageal cancer and one patient had esophageal metastasis from thyroid cancer. Mean standardized uptake values (SUVmean) of the cervical, thoracic (inside and outside the radiation fields) and lumbar spinal cord were measured.

RESULTS

SUVmean of the thoracic spinal cord inside the radiation field was decreased significantly after radiotherapy compared to those before radiotherapy (p < 0.001). SUVmean of the cervical spinal cord showed the same trend but it was not statistically significant (p = 0.051). SUVmean of the thoracic spinal cord outside the radiation field and the lumbar spinal cord did not differ significantly before and after the radiotherapy (p = 0.146 and p = 0.701, respectively).

CONCLUSIONS

The results suggest that glucose metabolism of the spinal cord is decreased in esophageal cancer patients after conventional dose radiotherapy.

Physiological Activity of Spinal Cord in Children: An 18F-FDG PET-CT Study

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate, in a pediatric population, F-Fluoro-deoxy-glucose (F-FDG) metabolic activity of normal spinal cord and to assess the correlation with demographic, clinical, and environmental variables.

SUMMARY OF BACKGROUND DATA

F-FDG uptake of normal spinal cord is variable in children. The knowledge of physiological metabolism of spinal cord is essential to distinguish normal from pathological findings by positron emission tomography-computed tomography (PET-CT).

METHODS

We retrospectively evaluated F-FDG positron emission tomography-computed tomography scans from a total of 167 pediatric patients (97 males; 3.9-18.9 yr) divided into 4 age groups (0-4.9 yr, 5-9.9 yr, 10-14.9 yr, and 15-18.9 yr), excluding those submitted to previous or recent therapeutic procedures influencing spinal cord metabolism or with central nervous system diseases. Spinal cord was divided into 3 levels (C1-C7; D1-D6; and D7-L1), and maximum standardized uptake value (SUVmax) of each cord level was measured. Correlations between SUVmax and spinal cord level, age, body weight, sex, type of disease, and season were statistically assessed.

RESULTS

Median SUVmax was similar and significantly (P < 0.01) higher at C1-C7 and D7-L1 levels than at D1-D6 level and it significantly (P < 0.01) increased with age in all spinal cord levels. A positive and significant association between SUVmax and body weight, female sex, and Hodgkin lymphoma was found. No significant association with season was observed. By multivariate analysis, only weight and female sex remained significant.

CONCLUSION

Knowledge of physiological F-FDG spinal cord activity in children is essential for a correct interpretation of positron emission tomography-computed tomography, especially in oncologic pediatric patients to avoid potential pitfalls.

LEVEL OF EVIDENCE

N/A.

[(18)F]-fluorodeoxyglucose-positron emission tomography in patients with active myelopathy

OBJECTIVE

To report and compare spinal cord [(18)F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) metabolism in 51 patients with active myelopathy.

PATIENTS AND METHODS

We retrospectively identified patients from January 1, 2001, through December 31, 2011, with active myelopathy in whom FDG-PET was performed. Inclusion criteria were (1) intramedullary myelopathy, (2) neoplastic/inflammatory etiology, and (3) FDG-PET performed after myelopathy onset. Exclusion criteria were (1) extramedullary myelopathy, (2) radiation-associated myelopathy, (3) no pathological confirmation of neoplasm, and (4) inactive myelopathy. Diagnostic categories of nonsarcoid inflammatory, neoplastic, and neurosarcoid were based on their final myelopathic diagnosis. Two radiologists who independently assessed FDG-PET for spinal cord hypermetabolism and maximum standardized uptake value (SUVmax) were blinded to the underlying etiology.

RESULTS

Fifty-one patients (53% women) with a median age of 60 years (range, 20-82 years) were included. Inflammatory myelopathic diagnoses (n=24) were as follows: paraneoplastic (n=13), autoimmune/other (n=5), inflammatory demyelinating (n=4), and transverse myelitis (n=2). Neoplastic diagnoses (n=21) were as follows: intramedullary metastases (n=12), intramedullary lymphoma/leukemia (n=7), and primary intramedullary neoplasm (n=2). Six patients had neurosarcoid myelopathy. Spinal cord hypermetabolism was more common with neoplastic myelopathy than with nonsarcoid inflammatory myelopathy (17 of 21 [81%] vs 6 of 24 [25%]; P<.001). Agreement between radiologist's assessments was excellent (κ=0.88). Median SUVmax was greater in neoplastic than in nonsarcoid inflammatory causes of myelopathy (3.3 g/mL vs 1.9 g/mL; P<.001). The FDG-PET hypermetabolism was seen in 3 of the 6 patients (50%) with neurosarcoid myelopathy (median SUVmax, 2.6 g/mL; range, 1.8-12.2 g/mL).

CONCLUSION

Spinal cord FDG-PET hypermetabolism in patients with active myelopathy may be reliably detected and was more common in neoplastic than in inflammatory myelopathies in this study. Future investigation of spinal cord FDG-PET is indicated to assess its potential contributions in evaluating active myelopathies.

Clinical value of 2-deoxy-[18F]fluoro-d-glucose positron emission tomography in patients with cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is one of the most common spinal cord disorders in the elderly. It is usually diagnosed by MRI, but in a significant number of patients the clinical course of CSM does not correlate with the extent of the spinal cord compression. Recent studies have suggested that a distinct metabolic pattern of the cervical cord, as assessed by PET with 2-deoxy-[18F]fluoro-d-glucose (18F-FDG) may predict a patient's clinical outcome after decompressive surgery for cervical spine stenosis. The authors provide an overview of the recent literature regarding the value of PET with 18F-FDG of the cervical cord in patients with CSM, paying attention to prognostic aspects and the potential role of inflammatory processes in the acute phase of the disease.

Changes in (18)f-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.

Pattern of 18F-FDG uptake in the spinal cord in patients with non-central nervous system malignancy

STUDY DESIGN

Retrospective review.

OBJECTIVE

To (1) propose a standard method to quantitate 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) uptake in the spinal cord and (2) use this methodology to retrospectively characterize the pattern of uptake within the entire spinal cord using whole-body positron emission tomography/computed tomography (PET/CT) imaging.

SUMMARY OF BACKGROUND DATA

A physiologic understanding of glucose metabolism within the spinal cord may provide insight regarding infectious, inflammatory, vascular, and neoplastic spinal cord diseases.

METHODS

Institutional review board approval was obtained. A total of 131 consecutive whole-body PET/CT studies from July to August 2004 were reviewed, and using exclusionary criteria of: (1) severe spinal arthropathy or curvature, (2) motion artifact, (3) canal hardware, (4) spinal tumor, and (5) marrow hyperplasia, 92 studies of neurologically intact patients (49 men and 43 women) were selected for a retrospective review of spinal cord 18F-FDG activity. The transaxial CT was used to define the canal and circular regions of interests were placed within the canal at the level of the vertebral body midpoint from C1 to L3. Region of interest total count, area, and maximum standardized uptake value (SUVmax) were recorded. Measurements at L5 served as an internal control. For comparative analysis, the cord-to-background (CTB) ratio was defined as spinal cord SUVmax to L5 SUVmax.

RESULTS

Mean CTB decreased along each spinal level from cranial to caudal (P < 0.001). Significant relative increases were observed at the T11-T12 vertebral body levels (P < 0.001). Although insignificant, a relative increase was observed at C4. No significant interactions of age or sex on CTB were observed.

CONCLUSION

The pattern of 18F-FDG uptake within the spinal cord, observed in patients with non-central nervous system malignancy, may be helpful in understanding glucose physiology of spinal cord diseases and warrants further research.

[Potential sources of diagnostic pitfall and variants in FDG-PET/CT]

Oncological FDG PET show variants and findings that may lead to a diagnostic error and that may be clarified by the morfofunctional imaging from PET/CT. In this article we show the experience acquired since a Siemens PET/CT Biograph LSO Pico3D was applied in our centre. We describe some representative examples of FDG distribution patterns which may lead to erroneous interpretations of the clinical studies when they refer to specific clinical situations. The examples included are classified into two main groups according to the cause: Technical and biological, and the latter into physiological and non-physiological (pathophysiological). Patterns are described within the biological group showing changes of the FDG biodistribution that may reduce the uptake in tumoural lesions, the physiological variants that may be interpreted as pathology, the effects of previous treatment and uptakes related to benign diseases.

CONCLUSION

We consider that knowledge of these variants and findings to be crucial in order to obtain optimal performance of PET/CT and to overcome the PET limitations.

Neurological improvement associated with resolution of irradiation-induced myelopathy: serial magnetic resonance imaging and positron emission tomography findings

We document serial magnetic resonance imaging (MRI) and [(18)F] 2-fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) findings in the process of improvement from delayed radiation necrosis of the spinal cord. A 61-year-old woman underwent radiotherapy for an oral carcinoma. Forty-six months later she developed a left-sided Brown-Séquard syndrome, suggesting incomplete cervical cord transection below the cervico-thoracic junction. Two months after starting steroid therapy, she had gradual clinical improvement, which continues 8 years after the termination of radiotherapy. Neurological improvement was associated with gradual resolution of an extensive high-intensity area within the cervico-thoracic spinal cord on MRI. Initially, the FDG-PET showed linear and uniform increase in FDG uptake throughout the cervical spinal cord with standardized uptake value of 2.68 +/- 0.16 (mean +/- SD), but it returned to normal value (1.90 +/- 0.14) at final follow-up. Considering that the normalization of FDG uptake correlated with neurological recovery, the uniform- and diffuse-increased FDG uptake noted in the initial course of myelopathy could reflect the metabolic activity of the compromised spinal cord.