[18F]Fluorodeoxyglucose positron emission tomography surveillance of hepatic metastases from prostate cancer following radiofrequency ablation: a case report.

The liver is the organ most commonly involved with metastatic disease. Surgical resection of hepatic metastases is the only potentially curative therapy, but it is possible in only 20 per cent of the patients. Radiofrequency ablation (RFA) of hepatic lesions is a therapeutic option for unresectable hepatic metastases. Today there is no clear consensus about which imaging technique is the most reliable to monitor RFA therapy. [18F]Fluorodeoxyglucose (FDG) positron emission tomography (PET) is a new imaging modality allowing evaluation of glucose metabolism that has become established for monitoring therapy and early detection of recurrence of various types of malignant tumors. We present a case report of a 61-year-old man treated for prostate carcinoma 3 years earlier who presented with rising serum prostate-specific antigen (PSA) levels. A CT scan demonstrated two hepatic metastases that were treated with RFA because the patient refused surgery. During 3 years of follow-up hepatic recurrence was monitored with serum PSA levels, CT of the abdomen, and FDG-PET imaging on multiple occasions. On three separate occasions FDG-PET revealed hypermetabolic foci despite no definite evidence of recurrence on CT. Furthermore FDG-PET imaging 2 months after the last RFA therapy showed two large photopenic areas without evidence of hypermetabolism consistent with successful RFA therapy. Serum PSA levels correlated better with FDG-PET than CT results. We conclude that in this patient FDG-PET imaging was more accurate than CT for monitoring recurrence of hepatic metastases from prostate carcinoma after RFA therapy. PET demonstrated hypermetabolic foci when there was recurrence and no evidence of hypermetabolism early after successful RFA therapy. In addition FDG-PET imaging helped to guide the placement of the RFA probe to the most metabolically active part of the tumor.

Unsuspected skeletal sarcoidosis mimicking metastatic disease on FDG positron emission tomography and bone scintigraphy.

Sarcoidosis is a disease process of unknown cause that exhibits heterogeneous clinical manifestations. Although the mediastinum and lungs are most commonly involved, the granulomatous process may also affect the skeleton, skin, eyes, kidneys, spleen, and liver. A 51-year-old woman with low back pain and no history of cancer was found to have a suspicious lesion at L4 on magnetic resonance imaging. Findings of bone scintigraphy were consistent with multiple metastases, and computed tomography of the chest identified two small indeterminate pulmonary nodules. Similarly, findings of fluorodeoxyglucose positron emission tomography were consistent with widespread skeletal metastases, but a primary tumor was not identified. Biopsy of a left femur lesion was diagnostic of active sarcoidosis with no evidence of cancer.

Calcium channel blockers: a potential cause of false-positive captopril renography.

PURPOSE: The purpose of the study was to review the causes of false-positive and false-negative captopril Tc-99m MAG3 renograms performed to evaluate renovascular hypertension at the authors' institution. METHODS: From May 2000 to January 2002, 77 patients were referred for evaluation of possible renovascular hypertension with captopril Tc-99m MAG3 renography. If the findings of the captopril study were abnormal, a baseline study was performed 3 days later. The captopril studies were retrospectively reviewed and correlated with available renal arteriography, magnetic resonance angiography, and duplex Doppler sonography studies and clinical follow-up. Renal artery stenosis greater than 70% on an arteriogram and 60% on Doppler studies or magnetic resonance angiography was considered positive for renovascular hypertension. RESULTS: There were five false-negative and four false-positive studies. The five patients who had the false-negative captopril studies underwent arteriography, which showed renal artery stenosis, and a stent was placed in two of them. The four false-positive captopril studies were proved by negative arteriograms in three and negative magnetic resonance angiography in one. Three patients with false-positive studies had bilateral renal function impairment after captopril and were taking calcium channel blockers at the time of the captopril study. One patient had a left nephrectomy and was also taking calcium channel blockers. CONCLUSION: Chronic intake of calcium channels blockers is a potential cause of bilateral symmetric false-positive captopril renography.

2-Deoxy-2-[18F]fluoro-D-glucose positron emission tomography uptake in a giant adrenal myelolipoma.

Incidental adrenal lesions found on anatomic imaging are not uncommon. 2-Deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging is highly accurate in the differentiation of benign from malignant adrenal lesions, both in patients with proven malignancy and with adrenal lesions detected incidentally. A 60-year-old white female with a history of lower mid-back pain underwent computerized tomography (CT) imaging that identified a 15-cm complex mass within the left adrenal gland with soft tissue, cystic, and adipose components. FDG-PET imaging showed significant hypermetabolic activity within portions of the mass with central photopenia suggesting a malignant lesion with central necrosis. Surgical excision and pathological examination, however, revealed a benign adrenal myelolipoma with extensive adenomatous and hematopoietic elements. Prior reports of adrenal myelolipoma evaluated with FDG-PET imaging have described no significant FDG uptake within these benign tumors. This case is an unusual example of histologically proven benign adrenal myelolipoma that was hypermetabolic on FDG-PET imaging. Correlation of pathologic and imaging findings demonstrated that the hypodense regions on CT were hypometabolic on FDG-PET and corresponded to cystic necrosis and adipose elements, whereas the adenomatous and hematopoietic elements were hypermetabolic.

Cerebral lesions incidentally detected on 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography images of patients evaluated for body malignancies.

OBJECTIVES: The purpose of this work was done to evaluate the value of including the brain in the field of view of a whole-body 2-deoxy-2-[18F] fluoro-D-glucose positron emission tomography (FDG-PET) study of patients referred for the evaluation of body malignancies. METHODS: A total of 1026 consecutive patients were included in this work. The primary diagnoses were the following: lung (n = 253), colorectal (n = 148), head and neck (n = 61), lymphoma (n = 249), melanoma (n = 84), and others (n = 231). Whole-body FDG images including the brain were acquired with a dedicated PET tomograph (GE advance, General Electronic Medical Systems, Milwaukee, WI) one hour after the intravenous administration of 10 mCi of FDG. Two experienced nuclear medicine physicians interpreted the images. Positive findings in the brain or the skull were correlated with other imaging studies and clinical follow-up. RESULTS: Abnormal findings were detected in 3.9% (40/1026) of the patients. Among the 40 abnormal focal lesions, 29 patients had a known history of cerebral disease, cerebrovascular or metastatic disease in most patients. Of the 11 patients without a prior history of cerebral disease, four patients had increased focal FDG uptake suggestive of metastases. Among these, two were proven clinically, one was proven to be a skull base metastasis on MRI, and the other had negative clinical follow-up, but only of two months duration. The other seven patients had a decreased focal FDG uptake most consistent with infarct, one was proven clinically, and the other six had a negative clinical follow-up (mean of 6.3 months, range 1-10), but had multiple risk factors for cerebrovascular disease. CONCLUSIONS: We conclude that FDG-PET screening for cerebral lesions in patients with body malignancy has little clinical impact. Unsuspected cerebral or skull metastases were detected in 0.4% (4/1026) of the patients.

Avaliação das hérnias discais lombares pela ressonância magnética / Magnetic resonance imaging in lumbar disc herniation

Com o objetivo de fazer uma revisão sobre hérnias discais lombares e seu diagn¢stico pela ressonância magnética (RM), os autores procederam a estudo retrospectivo de 296 pacientes, com um total de 357 hérnias discais lombares, através da avaliação de 785 exames de RM da coluna lombossacra realizados no per¡odo de 2/1/96 a 30/12/96, no CETAC -Centro de Tomografia Computadorizada e , Ressonância Magnética de Curitiba, A idade dos pacientes variou de 19 a 78 anos (média de 44,55 anos), Foi observada coincidência quanto à distribuição por sexo: 148 homens e 148 mulheres. Os autores apresentam também uma análise do tipo de hérnia, n¡vel e localização da mesma em relação ao canal vertebral e aos foramens neurais e suas implicaçães diagn¢sticas.