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Objective To explore the value of FDG PET-CT in the diagnosis of neurolymphomatosis (NL). Methods The clinical manifestation and FDG PET/CT imaging results in a patient with diffuse large B cell lymphoma accompanying peripheral neuropathy which was confirmed by pathological examination, were introduced. The images as shown by PET/CT were compared with the findings of traditional imaging including MRI and CT. Relevant literature was reviewed. Results A 38-year female patient complaining of left chest-back pain for 2 months came to hospital for treatment. An enhanced MRI of thoracic vertebrae showed osseous destruction on the left side of 4th thoracic vertebra and left posterior segment of 5th rib, and it was primarily diagnosed as a tumor. FDG PET/CT revealed a massively increased radioactive uptake in intervertebral foramen of left 4th, 5th thoracic vertebrae. The lesion was shown as an increase in uptake of radio-active substance along the left 5th intercostal nerve in the form of bundle or threads. A round-like nodule with increased radioactive uptake was observed in the left parasternal 2nd intercostal space. A CT-guided percutaneous needle biopsy of the nodule revealed a diffuse large B-cell lymphoma (A type). The lesion was shown to involve 4th, 5th thoracic vertebrae and left 5th intercostal nerve. It was diagnosed as NL. Repeated FDG PET imaging after chemotherapy showed normal radioactive distribution in the site of primary lesion area. Conclusions PET/CT is effective and sensitive in the diagnosis of NL, especially in patient with a history of malignant hematologic disease with clinical symptoms concerning peripheral nerve, accompanied by negative results with other examinations. Comparing with MRI, PET/CT can reveal involvement of peripheral nerve earlier, better reflect the degree of pathological condition, and reveal the number of nerves involved, as well as size and morphology of the lesion. It can reveal the active lesions of NL, and provide the target for needle biopsy.
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<p><b>OBJECTIVE</b>To investigate the value of incidental focal (18)F-FDG uptake in the colon and rectum and characteristics of functional anatomic form for differential diagnosis of colorectal benign or malignant diseases.</p><p><b>METHODS</b>Clinical data and images of incidental focal hypermetabolism focus in colon and rectum of 37 individuals undergoing (18)F-FDG PET-CT were analyzed retrospectively. According to the eventual outcomes of pathological examination and clinical follow-up, these cases were divided into four subgroups: malignant disease, benign tumor (including precancerous change), inflammation and physiological uptake. Radioactive uptake level (SUVmax) and change of delayed imaging (RI) of focal hypermetabolism focus were compared between groups. The data analysis was performed using variance analysis.</p><p><b>RESULTS</b>The average SUVmax was 6.3±3.7, 8.8±6.5, 5.2±1.4, and 3.8±0.9 in malignant disease (n=11), benign (precancerous) tumor (n=9), inflammation (n=9) and physiological uptaking (n=8) respectively. The average SUVmax was 7.6±5.6 in benign and malignant tumor, and 4.7±1.5 in inflammation and physiological uptake. The distinction of average SUVmax was not statistically significant between benign and malignant tumor or inflammation and physiological uptake. But it was higher in tumors as compared to inflammation or physiological uptake with a statistically difference (P<0.05). The RI was 0.3±0.2, 0.4±0.1, 0.3±0.2, 0.4±0.2 in above 4 groups respectively, and the differences were not statistically significant.</p><p><b>CONCLUSIONS</b>The incidental focal hypermetabolism focus in the colon the rectum during (18)F-FDG PET-CT may indicate potential colorectal malignant diseases and precancerous lesions. SUVmax value in focal hypermetabolism focus in the colon and rectum can help to distinguish tumor from inflammation or physiological uptake. But there is no diagnostic value for distinguishing malignant disease from benign tumor.</p>