Language localization with activation positron emission tomography scanning.

We report the first instance of the use of 3-dimensional magnetic resonance imaging anatomically correlated to positron emission tomography (PET) scanning to identify language areas in a patient with an arteriovenous malformation (AVM) in the posterior speech region. The patient was a 24-year-old right-handed woman with an angiographically proven AVM (3-4 cm) in the left mid-posterior second temporal convolution in whom a left intracarotid injection of sodium Amytal produced significant language disruption. A baseline PET cerebral blood flow study identified the AVM, and an activation PET scan performed during the reading and speaking of simple words showed increased activity in the left parastriate cortex (the second visual area), in the left posterior third frontal convolution (Broca's area), and in the left inferior and midtemporal gyri (Wernicke's area). Increased activity was also noted in the right and left transverse temporal (Heschl's) gyri, in the left precentral gyrus, in the left medial superior frontal gyrus (the supplementary motor area), and in the right cerebellum. We conclude that activation PET scanning is useful in the preoperative assessment of patients who harbor cerebral AVMs in classically described speech regions.     

Functional evaluation of microvascular free flaps with positron emission tomography.

BACKGROUND: The aim of this study was to assess blood flow (BF) of microvascular free flaps studied with positron emission tomography (PET) in patients with head and neck squamous cell cancer (HNSCC) undergoing major radical surgery 3-4 weeks after high-dose radiotherapy. METHODS: Five patients underwent resection of the HNSCC of the oral cavity followed by microvascular reconstruction with a radial forearm flap. Regional BF in oral and neck tissues was measured with PET using radiolabelled water ([15O]H2O) twice (1-2 and 12-14 days, respectively) following radical surgery. RESULTS: In the first postoperative PET study, the median BF in the cutaneous flap area was 5.1 mL/100 g/min, and in the muscle contra-lateral to the recipient site 19.9 mL/100 g/min. A low flap-to-muscle BF ratio appeared to correlate with circulatory incongruity, and thus with poorer flap success. The follow-up study on the second postoperative week supported the results of the primary PET scan. CONCLUSIONS: This pilot study suggests that PET using [15O]H2O is a feasible method to quantitatively evaluate BF of the whole free flap in patients operated on for oral     

F-18-fluorodeoxyglucose positron emission tomography as a presurgical evaluation modality for I-131 scan-negative thyroid carcinoma patients with local recurrence in cervical lymph nodes

BACKGROUND: F-18-labeled fluorodeoxyglucose-positron emission tomography (FDG-PET) has a supplementary role in localizing recurrent sites of differentiated thyroid carcinoma. We evaluated whether FDG-PET is feasible as a presurgical evaluation modality for I-131 scan-negative thyroid carcinoma patients. METHODS: Preoperative FDG-PET results were compared with the pathologic findings of lymph nodes specimens of 22 papillary thyroid patients. All patients had thyroidectomy and I-131 ablation therapy beforehand and showed negative I-131 scans on follow-up studies. RESULTS: In 85 cervical lymph node groups dissected, 56 lymph node groups revealed metastasis. The sensitivity and specificity of FDG PET for metastasis were 80% (45 of 56) and 83% (24 of 29), respectively. Among the pathologically positive 33 lymph nodes with normal size(< or =1 cm), FDG-PET detected 23 nodes. Serum thyroglobulin levels were elevated in 12 patients (sensitivity, 55%). CONCLUSION: FDG-PET accurately detected the recurred cervical lymph nodes of differentiated thyroid carcinoma patients who showed negative I-131 scan. FDG-PET is suitable for the presurgical evaluation of these patients.     

Angiocentric glioma and surrounding cortical dysplasia manifesting as intractable frontal lobe epilepsy--case report

A 26-year-old man presented with a case of angiocentric glioma manifesting as medically refractory epilepsy. Magnetic resonance imaging revealed a hyperintense lesion in the right superior frontal gyrus on T(2)-weighted imaging, with cortical hyperintense rim on T(1)-weighted images and minimum contrast enhancement. Video-electroencephalography (EEG) monitoring characterized his seizures as originating from the right frontal lobe. Long-term EEG recording from implanted subdural electrodes disclosed epileptic activities extending beyond the margin of the radiological lesion. Extended cortical resection of the superior frontal gyrus including the tumor and the surrounding epileptic cortices was performed. Postoperatively, he became seizure-free with antiepileptic medication during a 12-month follow-up period. Histological examination of the surgical specimen showed the characteristic findings of angiocentric glioma. Associated cortical dyslamination consistent with cortical dysplasia was found in the surrounding cortex. Angiocentric glioma is a slow-growing or stable tumor frequently presenting with intractable epilepsy. Surgical treatment would be aimed primarily at control of epilepsy. Complete lesionectomy usually results in postoperative seizure freedom, but the present case shows evidence for associated cortical dysplasia with this tumor entity. Careful pre-surgical evaluation for epilepsy is necessary to achieve better seizure outcome.     

11C-choline positron emission tomography for the evaluation after treatment of localized prostate cancer

RATIONALE: The evaluation of the efficacy of the treatment of men with prostate cancer is largely based on post treatment levels of PSA. An increase in PSA or biochemical recurrence is the first sign of recurrent disease and precedes a clinically detectable recurrence by months to years. Digital rectal examination and conventional imaging techniques are not sensitive to detect a local recurrence. A metabolic imaging technique, which is not dependent on anatomical distortions, could be of use. In this study we investigated 11C-choline positron emission tomography (PET) for the evaluation after treatment of localized prostate cancer. METHODS: Thirty-six patients with localized prostate cancer, treated by either radical prostatectomy (n=20) or by external beam radiotherapy (n=16) were studied with 11C-choline PET. The results of PET were compared with the results of histology and with clinical follow up. RESULTS: Fourteen patients had no biochemical failure after therapy. 11C-choline PET was true negative in 14/14 patients. Twenty-two patients had a biochemical failure. In the radical prostatectomy patients 11C-choline PET was true positive in 5/13 (38%) cases. In the external beam radiotherapy patients 11C-choline PET was true positive in 7/9 (78%). The recurrent tumor was confirmed by biopsy or by bone scan in eleven of the twelve true positive patients. In ten patients with a negative 11C-choline PET scan, no recurrent tumor could be proven yet clinically, by biopsy or during follow up. CONCLUSION: 11C-choline PET is a feasible technique for evaluation of treatment for localized prostate cancer. The site of recurrence was detected correctly in 78% of the patients after external beam radiotherapy compared to 38% of the patients after radical prostatectomy. No positive PET scans were observed sofar in patients with a serum PSA <5ng/ml. Confirmatory studies and longer follow up are needed to determine the efficacy of 11C-choline PET compared to other imaging techniques.     

Role for positron emission tomography in skeletal diseases

Imaging plays a prominent role in the diagnosis and management of rheumatic diseases. Conventional imaging methods provide high-resolution structural information but usually fail to distinguish between active lesions and residual changes. Positron emission tomography (PET) with the tracer 18F-fluorodeoxyglucose (18F-FDG) was recently introduced into clinical practice as a means of obtaining information on both structure and metabolic activity. 18F-FDG-PET is widely used in oncology and may be valuable in patients with infections or inflammatory diseases, most notably vasculitis. Although encouraging results have been published, the number of studies remains small, as 18F-FDG-PET is an expensive investigation that is not available everywhere. Further work is needed to determine the cost-effectiveness ratio of 18F-FDG-PET in patients with infections or inflammatory diseases. Imaging plays a prominent role in the diagnosis and management of many musculoskeletal diseases. Although considerable progress has been made recently, the structural information supplied by conventional imaging methods is inadequate in some patients. Positron emission tomography (PET) after injection of 18fluorodeoxyglucose (18F-FDG) provides information on tissue metabolism. The usefulness of 18F-FDG-PET in oncology is now widely recognized. Other uses are emerging, in part thanks to the development of new cameras that combine dedicated detectors and an X-scanner in order to ensure accurate three-dimensional localization of metabolically active lesions. However, the exact role for 18F-FDG-PET needs to be studied in larger populations of patients.     

Incidental thyroid carcinoma identified by positron emission tomography scanning obtained for metastatic evaluation.

Positron emission tomography (PET) scanning is an emerging technology with substantial implications for patients with solid tumors. PET is useful in identifying sites of metastatic disease as well as primary malignancy and evaluating suspicious findings found via other imaging modalities. PET is becoming a standard modality for metastatic evaluation of a variety of malignancies. However, this imaging is not limited by histology and may reveal clinically occult second lesions. We present five cases of a clinically occult thyroid cancer found in patients who underwent PET scanning for metastatic evaluations. The principal diagnoses included two patients with malignant melanoma, one each with gastric, rectal, and colonic adenocarcinoma. None of the cases had findings on physical examination. Increased uptake in the region of the thyroid was evident on the PET scan, and fine-needle aspiration biopsy indicated papillary carcinoma of the thyroid in all five cases. Although evaluation of metastatic disease is the primary purpose for PET in this setting the discovery of occult thyroid malignancy is an additional benefit of such imaging. This emphasizes the importance of investigating suspicious areas found by PET and not simply assuming that these are all sites of metastatic disease. Furthermore incidental findings of uptake in the region of the thyroid make consideration of a primary carcinoma mandatory.     

Unusual positron emission tomography findings in pulmonary amyloidosis: a case report

Positron emission tomography (PET) has come to play an increasingly important role in the evaluation of pulmonary lesions, which are suspicious of malignancy. As is true for other techniques, PET gives false positive and negative results. We report a case of pulmonary amyloidosis with multiple pulmonary nodules showing different uptake of 18 F-fluorodeoxyglucose (FDG) on PET. There are limitations of specificity of FDG-PET in characterising pulmonary nodules and it is important to confirm a suspected malignancy with histology before potentially curative treatment is undertaken.     

Prospective evaluation of positron emission tomography in the preoperative staging of esophageal carcinoma

HYPOTHESIS: Positron emission tomography (PET) is a useful tool in the selection of patients with esophageal cancer who may not benefit from esophageal resection. DESIGN: Case series. SETTING: Tertiary care hospital. PATIENTS: Eighty-one patients with newly diagnosed esophageal cancer who underwent PET and computer tomography (CT) of the chest and abdomen (and of the neck in 45 patients) within 45 days were included. MAIN OUTCOME MEASURES: We calculated the sensitivity and specificity in detecting metastatic sites on the basis of 31 histologically verified lesions. In addition to results obtained on CT, the information provided by PET was evaluated with a view to the choice of management strategies. RESULTS: The PET findings had a higher specificity (89% vs 11%) but a lower sensitivity (38% vs 63%) than CT findings in the detection of metastatic sites. The CT results showed greater agreement with histopathological findings than did PET results. In 8 patients (10%), PET detected distant metastases that were not identified with CT. In 4 patients (5%), PET detected bone metastases only, but in all of these patients metastases in other locations were detected by CT. Although PET led to upstaging (M1) in 2 patients (2%), it did not enable the exclusion of esophageal resection. CONCLUSIONS: Preoperative PET was not characterized by greater accuracy in the detection of metastatic sites previously identified by CT. Therefore, PET did not lead to a change in the indication for esophagectomy. An increase in the sensitivity and the combined use of CT and PET may lead to new indications for this staging procedure.     

Advances in positron emission tomography applications for urologic cancers

PURPOSE OF REVIEW: Molecular imaging in oncology utilizes advances in imaging technology with probes that image key molecules and molecular based events that are fundamental for malignant change and progression. PET in combination with computed tomography will be the means by which molecular imaging will be translated into the advanced practice of urology. This review introduces the concept of molecular imaging and summarizes current and future molecular imaging approaches that are likely to have a major impact on clinical practice in the near future. RECENT FINDINGS: In renal cancer, a radiolabeled antibody, iodine-124 cG250, shows promise for improving management of small clear-cell renal cancers through noninvasive immunologic identification as a basis for differential diagnosis of other renal masses. In prostate cancer, antibodies to key antigens, such as prostate specific membrane antigen, along with metabolic probes, for glycolysis (fluorodeoxyglucose) and amino acid transport (C-11 methionine) are likely to improve early detection of regional and distant metastases and provide a basis for improved monitoring of treatment response. SUMMARY: Molecular imaging, through PET/computed tomography will help individualize patient care for surgical urology. Applications will include noninvasive image-based immunotyping of human cancers and metabolic based staging, detection and treatment monitoring for urologic malignancies.     

11C-acetate positron emission tomography for occult prostate cancer

We report, to our knowledge previously not described, a case of occult prostate cancer, in which 11C-acetate positron emission tomography disclosed tumor manifestation after failure of conventional diagnostic procedures.     

Prospective evaluation of soft tissue masses and sarcomas using fluorodeoxyglucose positron emission tomography

BACKGROUND: The differentiation of soft tissue sarcoma (STS) from benign masses is difficult owing to their clinical and radiological similarities. Accurate staging is hindered by the large number of sites at which metastases may be found. This study examined the value of whole-body [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) in patients presenting with soft tissue masses. METHODS: Thirty patients with a soft tissue mass suspected to be malignant were evaluated with FDG PET. The images were evaluated qualitatively and quantitatively for uptake of FDG to determine whether benign lesions could be differentiated from malignant tumours, and for the presence of metastases. RESULTS: Thirty-one masses were removed from 30 patients; 12 were benign and 19 were malignant STSs. Using qualitative assessment of the FDG PET images, all the high-grade STSs (n = 12) were correctly identified, but low-grade STS (n = 7) could not be differentiated from a benign lesion. Using a quantification assessment, there was a 95 per cent sensitivity and a 75 per cent specificity in diagnosing STS. Three patients had metastases at presentation; two were correctly identified by FDG PET. Conclusion: FDG PET has a role in distinguishing high-grade STS from low-grade or benign STS and may have a role in staging malignant tumours.