Evaluation of recurrent gastric malignancy with [F-18]-FDG positron emission tomography

AIM

We retrospectively assessed the use of [(18)F] fluorodeoxyglucose positron emission tomography (FDG PET) in the evaluation of recurrent disease in patients with history of gastric malignancy.

MATERIALS AND METHODS

Eighteen patients were referred for FDG PET for evaluation of recurrent gastric cancer. Prior treatments included total (n = 4) or partial gastrectomy (n = 14) followed by chemotherapy alone (n = 7) or combined chemoradiation therapy (n = 2). The interval between the most recent treatment and PET ranged from 3 months to 2 years. Correlative diagnostic data were available in 16 patients and were all obtained within 3 months of the PET study. Validation was by clinical or imaging follow-up (2-45 months) in 16 patients and histology in two patients.

RESULTS

PET was concordant with computed tomography (CT) in 12 patients (5 TP, 6 TN, 1 FN). In one patient with negative imaging studies, an incidental finding of left obstructive uropathy was determined to be due to metastatic ureteral stricture. Discordant imaging findings were present in four patients (22% of total). PET-detected diffuse metastatic lesions in three of these patients with rising serum tumour markers while other imaging studies were negative. Additional chemotherapy was initiated in these three patients (17% of total) based on PET localization of disease. PET and a gastric anastomosis biopsy were negative in another patient with positive CT. The remaining two patients without correlative imaging studies died shortly after positive PET studies with presumed recurrent cancer.

CONCLUSION

FDG PET may be useful in the evaluation of recurrent gastric cancer, and can localize the disease when CT is non-diagnostic. Imaging evaluation with PET may also impact on the clinical management of patients with recurrent gastric cancer.

FDG-PET in the detection of gastrointestinal metastases in melanoma

We report six cases of malignant melanoma metastatic to the small bowel in which the information obtained from fluorodeoxyglucose positron emission tomography (FDG-PET) contributed significantly to the management of the patients. In each of these cases the conventional diagnostic work-up missed findings that were important for treatment planning. We conclude that FDG-PET is a valuable modality in melanoma patients with suspected gastrointestinal involvement. It is also a sensitive technique for the diagnosis of other intra-abdominal as well as extra-abdominal metastases.

Persistent postictal hyperperfusion demonstrated with PET

Four patients with complex partial seizure disorder whose positron emission tomography (PET) scans show sustained hyperperfusion of the epileptiform focus 12-24 h after a seizure episode are presented. Three of these patients underwent same day Fluorine-18 (18F) deoxyglucose (FDG) PET scans, which showed hypometabolism of the epileptic temporal lobe. In one patient who underwent repeated blood flow and concurrent glucose metabolism scans 4 days after a seizure, hyperperfusion was not present and the FDG-PET demonstrated hypometabolism. Persistent hyperperfusion was noted in six out of 65 cases studied. Four out of six patients who were followed clinically were presented in this report. The cause of the rare occurrence of persistent postictal or interictal hyperperfusion and the differences of postictal blood flow dynamics and glucose metabolism need to be clarified further with future studies.

Comparison of fluorine-18 deoxyglucose and O-15 water PET in temporal lobe epilepsy

This study reports a comparison of Fluorine-18 deoxyglucose positron emission tomography (FDG-PET) and O-15 water (H2(15)O) PET with regard to lateralization of the seizure focus in patients with complex partial epilepsy. The analysis of 35 patients who had an anterior temporal lobectomy for medically intractable seizures indicated that FDG- and H2(15)O-PET were highly correlated in demonstrating the epileptic focus. FDG- and H2(15)O-PET showed significant asymmetries in 83% and 77% of cases respectively. The lateralization with visual analysis of MRI was found to be lower than both FDG and blood flow imaging. Ictal electroencephalography (EEG) lateralizations were concordant with sites of blood flow and FDG-PET abnormalities. Thirty-three patients (94%) were seizure-free or improved significantly after surgery. In conclusion, blood flow PET yielded similar results compared to FDG-PET and can be a valuable modality in preoperative evaluation of patients with temporal lobe epilepsy.

FDG positron emission tomography in diffuse Lewy body disease: a case report

Lewy body disease is a clinicopathologic condition that includes Parkinson's disease at one end and diffuse Lewy body disease at the other hand. The latter is often associated with progressive cognitive deterioration, levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, and visual and auditory hallucinations. In addition, it can be a familial disease. Clinical and positron emission tomographic findings are described in a patient with atypical dementia and movement disorder and a pathologically proved diagnosis of diffuse Lewy body disease.

Language mapping in pretreatment planning of patients with cerebral arteriovenous malformation: a PET study

PURPOSE

Three patients who had cerebral arteriovenous malformations underwent language mapping by positron emission tomography (PET) to identify the dominant hemisphere for language and the spatial relation of lesions to language areas.

METHODS

Mapping was performed to assess the risk that surgery could cause neurologic deficits and to plan other therapeutic strategies.

RESULTS

The information obtained by PET language mapping changed the course of management for these patients. Two patients were treated with stereotactic radiosurgery and one patient with surgical resection.

CONCLUSIONS

PET imaging can be a valuable noninvasive tool for mapping the functional cortex and for preoperative planning of different treatment options in patients with arteriovenous malformations.

Presurgical lateralization of seizure focus and language dominant hemisphere with O-15 water PET imaging

OBJECTIVES

The purpose of this study was to assess the value of same day blood flow PET in both the identification of the language dominant hemisphere and in the lateralization of the epileptic focus in patients who were preoperatively evaluated for complex partial seizures.

METHODS

The charts of 24 patients who had temporal lobectomies for seizures were retrospectively reviewed. All PET scans were acquired by using O-15 water tracer (H2(15)O) in both resting and language activation conditions. PET language laterality results were compared to Intracarotid amytal procedure (IAP) results. For epileptic focus lateralizations, regions of interest (ROI) analysis of temporal lobes was performed on resting scans.

RESULTS

IAP testing was discordant with PET language mapping in 1 out of 24 cases. This patient had a decline in cognitive abilities as measured by postoperative neuropsychologic testing. For epileptic focus lateralization, the PET was highly sensitive (87%) and specific (100%). Lateralizations with the PET were in agreement with surgical sites in all cases. Eighteen patients (75%) were seizure free and 4 patients (17%) were significantly improved after surgery.

CONCLUSION

The results suggest that O-15 water PET is sensitive and specific in both the lateralization of epileptic focus and the language dominant hemisphere and can be a cost-effective and noninvasive method in presurgical evaluation of patients with complex partial seizures.