PURPOSE: To evaluate use of functional imaging with positron emission tomography (PET) versus computed tomography (CT) for detection of extranodal lymphoma spread. MATERIALS AND METHODS: Eighty-one consecutive and previously untreated patients with malignant non-Hodgkin lymphoma (n = 43) or Hodgkin disease (n = 38) were examined with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) PET and contrast material-enhanced CT. Concordant findings at both CT and FDG PET were regarded as actual locations of disease; discordant results were resolved on the basis of biopsy or follow-up results when possible. RESULTS: Forty-two lesions were identified at both PET and CT, and 19 were verified with biopsy results. PET demonstrated a further 24 lesions. Verification was possible in 15 of these lesions with biopsy (n = 10), magnetic resonance imaging (n = 1), scintigraphic (n = 1), or follow-up (n = 3) results. In 14 of these 15 lesions, PET findings were confirmed (bone marrow, nine; spleen, three; other, two). Seven lesions not visualized at FDG PET were identified at CT, six of which were verified with biopsy (n = 2) or follow-up (n = 4) results. Five of these six CT findings were found to be erroneous. In 13 patients, PET findings led to changes in tumor staging. CONCLUSION: PET may provide more information about extranodal lymphoma than does incremental CT.
Radionuclide bone scanning (RNB) is considered to be the most practical screening technique for assessing the entire skeleton for skeletal metastases. However, RNB has been shown to be of lower sensitivity than MRI and CT in detecting osteolytic metastases. A prospective study was designed to evaluate the accuracy of planar RNB versus tomographic bone imaging with 18F-labeled NaF and PET (18F PET) in detecting osteolytic and osteoblastic metastases and its dependency on their anatomic localization.Forty-four patients with known prostate, lung or thyroid carcinoma were examined with both planar RNB and 18F PET. A panel of reference methods including MRI of the spine, 1311 scintigraphy, conventional radiography and spiral CT was used as the gold standard. RNB and 18F PET were compared by a lesion-by-lesion analysis using a five-point score for receiver operating characteristic (ROC) curve analysis.18F PET showed 96 metastases (67 of prostate carcinoma and 29 of lung or thyroid cancer), whereas RNB revealed 46 metastases (33 of prostate carcinoma and 13 of lung or thyroid cancer). All lesions found with RNB were also detected with 18F PET. Compared with 18F PET and the reference methods, RNB had a sensitivity of 82.8% in detecting malignant and benign osseous lesions in the skull, thorax and extremities and a sensitivity of 40% in the spine and pelvis. The area under the ROC curve was 0.99 for 18F PET and 0.64 for RNB.18F PET is more sensitive than RNB in detecting osseous lesions. With RNB, sensitivity in detecting osseous metastases is highly dependent on anatomic localization of these lesions, whereas detection rates of osteoblastic and osteolytic metastases are similar. Higher detection rates and more accurate differentiation between benign and malignant lesions with 18F PET suggest the use of 18F PET when possible.
Hepatobiliary and renal elimination of cysteinyl leu-kotrienes were investigated in a mutant rat strain with a hereditary defect in the hepatobiliary excretion of conjugated bilirubin, dibromosulfophthalein and oua-bain. After intravenous injection of [3H]leukotriene C4, the initial half-life of radioactivity circulating in blood was 79 ± 15 sec (S.D.) in transport mutant rats as compared to 31 ± 6 sec (S.D.) in normal Wistar rats. The intrahepatic leukotriene radioactivity was increased 5-fold after 1 hr in mutant rats, while the biliary elimination of [3H]Ieukotrienes was reduced to 1.8% of control. In normal rats, 77 ± 7% (S.D.) of the administered leukotriene radioactivity were recovered in bile within 1 hr. The total recovery of radioactivity from bile, urine, liver, intestine, stomach, kidneys, muscular system and blood 1 hr after intravenous [3H]leukotriene C4 was 89 ± 6% (S.D.) in normal rats and 46 ± 4% (S.D.) in transport mutants. Enterohepatic circulation was studied after intraduodenal administration of N-acetyl-[3H]leukotriene E4, a major cysteinyl leukotriene metabolite in rat bile. In transport mutants, hepatobiliary elimination of the intestinally absorbed [3H]leukotriene was reduced to 5%, whereas urinary excretion was not significantly affected. [3H]Leukotriene metabolites in bile, liver and urine were separated by reversed-phase high-performance liquid chromatography. The proportion of N-acetyl-[3H]leukotriene E4 relative to polar leukotriene metabolites was higher in the bile of transport mutants as compared to control Wistar rats when analyzed within 30 to 60 min after intravenous injection of [3H]leukotriene C4. Our results indicate that the cysteinyl leukotrienes are physiological substrates of the can-alicular transport system for organic anions such as dibromosulfophthalein. The transport mutant rats serve to characterize the hepatobiliary excretion system for cysteinyl leukotrienes.
Clinical diagnosis of skeletal tumors can be difficult, because such lesions compose a large, heterogeneous group of entities with different biologic behaviors. The aim of this prospective study was to assess the value of PET in grading tumors and tumorlike lesions of bone.Two hundred two patients with suspected primary bone tumors were investigated using FDG PET. Uptake of FDG was evaluated semiquantitatively by determining the tumor-to-background ratio (T/B). All patients underwent biopsy, resulting in the histologic detection of 70 high-grade sarcomas, 21 low-grade sarcomas, 40 benign tumors, 47 tumorlike lesions, 6 osseous lymphomas, 6 plasmacytomas, and 12 metastases of an unknown primary tumor.All lesions, with the exception of 3 benign tumors, were detected by increased FDG uptake. Although sarcomas showed significantly higher T/Bs than did latent or active benign lesions (P < 0.001), aggressive benign lesions could not be distinguished from sarcomas. Using a T/B cutoff level for malignancy of 3.0, the sensitivity of FDG PET was 93.0%, the specificity was 66.7%, and the accuracy was 81.7%.FDG PET provides a promising tool for estimating the biologic activity of skeletal lesions, implicating consequences for the choice of surgical strategy.
The purpose of the present paper is to assess clinical value of PET in oncology on the basis of published studies.Clinical value of PET in oncology was evaluated by a panel of recognized experts in the framework of an interdisciplinary consensus conference. On the basis of PET studies, well documented in the international literature, the value of PET for solving clinical questions was classified according to the following categories (classes 1a, 1b, 2a, 2b, 3): "appropriate" (1a), "mostly acceptable" (1b), "helpful" (2a), "value as yet unknown" (2b), "useless" (3).2-fluorodeoxyglucose (FDG) acts as the radiopharmaceutical of choice for PET in clinical oncology. PET is indicated (1a) for diagnosing relapse in high grade glioma (FDG) or low grade glioma (C-11 methionine or F-18 fluorotyrosine), differential diagnosis of solitary peripheral pulmonary nodules in high risk patients and for diagnosis of pancreatic carcinoma. PET may be clinically used (1b): In "low-grade" glioma, search for unknown primary in head and neck tumors, suspicion of relapse in non-small cell bronchial carcinoma (NSCBC) and colorectal carcinoma, lymphnode staging in NSCBC, pancreatic carcinoma, muscle invasive bladder carcinoma and testicular cancer. Staging of Hodgkin's disease (HD, stage I/II vs III), early therapy control in patients with a residual mass or suspicion of relapse in HD and in high grade NHL, lymph node staging and search for distant metastases in malignant melanoma (Breslow > 1.5 mm), search for lymph node or distant metastases in differentiated thyroid cancer with elevated hTG and a negative radioiodide whole body scan. Many further indications are emerging, but are not yet sufficiently well documented in the literature. For most indications beside scientific studies, an individual cost benefit utility evaluation by the responsible physician is recommended.Metabolic imaging of PET provides for many principle advantages compared to conventional anatomically based cross sectional imaging. For routine use in oncology a detailed assessment of specific efficiency of PET is indicated.
✓ The syndrome of spontaneous intracranial hypotension is characterized by orthostatic headaches in conjunction with reduced cerebrospinal fluid (CSF) pressure or CSF volume, and characteristic magnetic resonance (MR) imaging findings. A 50-year-old man presented with a 1-year history of paroxysmal ataxia of gait and short attacks of blurred vision when he stood up from a recumbent position and began to walk. Orthostatic headache was not a feature of his clinical presentation. Magnetic resonance images of the brain revealed diffuse enhancement of the dura mater and hygromas over both cerebral convexities. Magnetic resonance images of the spine demonstrated dilated cervical epidural veins and dilation of the perimedullary veins. Radionuclide cisternography identified a CSF leakage that was localized to the T12—L1 level on subsequent myelograms and on computerized tomography scans obtained after the myelograms. An epidural blood patch was administered and visualized with tungsten powder. The patient's clinical symptoms and sites of disease on imaging completely resolved. The unusual clinical presentation in this case—paroxysmal ataxia of gait, lack of orthostatic headaches, and dilated epidural and perimedullary venous plexus—supports a recently noted broadening of both the clinical and imaging characteristics of spontaneous intracranial hypovolemia.
