Whole-body Imaging Technique Research Articles

Somatostatine et scintigraphie des récepteurs de la somatostatine : quel intérêt pour le rhumatologue ?

Somatostatin is a hormone that regulates several physiological cell processes via specific receptors expressed throughout the body, in particular by nerve cells, many neuroendocrine cells, and cells mediating inflammation and immune responses. Somatostatin receptor scintigraphy achieved by administration of somatostatin labeled with a γ-emitting isotope has become an integral part of the work-up and treatment monitoring program in patients with neuroendocrine tumors, most of which overexpress somatostatin receptors. Several studies have convincingly established that somatostatin receptor scintigraphy benefits patients with a number of chronic inflammatory diseases, including sarcoidosis and other granulomatous diseases. In the evaluation of hematological diseases and detection of mesenchymatous tumors manifesting as oncogenic osteomalacia, the preliminary results are sufficiently promising to warrant larger studies aimed at defining the role for this noninvasive whole-body imaging technique. In the treatment area, the development of somatostatin analogs with antisecretory and antiproliferative effects has radically changed the management of gastroenteropancreatic neuroendocrine tumors and pituitary tumors. The antiinflammatory and analgesic effects of these drugs remain incompletely understood but may prove useful in a number of autoimmune diseases.

Radionuclide three-phase whole-body bone imaging.

To describe the radionuclide three-phase whole-body bone imaging (TPWBBI) technique and discuss the usefulness of its application. TPWBBI was performed after a single intravenous injection of 555 to 925 MBq (15 to 25 mCi) Tc-99m MDP. Whole-body arterial flow (phase one) followed by blood-pool and tissue perfusion (phase two) images were obtained with the moving detector head speed set at 150 cm/minute and 40 cm/minute, respectively. Conventional whole-body static bone images (phase three) were obtained 3 hours later. When 542 consecutive TPWBBI results were reviewed, 394 (166 extraskeletal and 228 skeletal) abnormalities were detected during phases one and two. The 166 extraosseous lesions included vascular diseases: abdominal aortic aneurysms and peripheral vascular diseases and renal abnormalities, liver abnormalities, ascites, and pleural effusions. Many of these were incidentally detected clinically significant findings and would not have been identified on conventional static bone images. It helps to differentiate among acute and chronic fractures, active and inactive inflammatory diseases such as arthritis or osteomyelitis, and Paget's disease. With a single injection of Tc-99m MDP, whole-body images obtained in the arterial phase, the blood-pool and tissue perfusion phase, and the static bone phase can identify many clinically significant skeletal and soft tissue abnormalities. TPWBBI can differentiate between active and inactive phases of different disease processes and thereby provide a diagnosis that is more specific than a conventional single-phase bone scan. It may be applicable as a tool for nuclear physical examination.

From tumor biology to clinical Pet: a review of positron emission tomography (PET) in oncology.

Cancer cells show increased metabolism of both glucose and amino acids, which can be monitored with 18F-2-deoxy-2-fluoro-D-glucose (FDG), a glucose analogue, and 11C-L-methionine (Met), respectively. FDG uptake is higher in fast-growing than in slow-growing tumors. FDG uptake is considered to be a good marker of the grade of malignancy. Several studies have indicated that the degree of FDG uptake in primary lung cancer can be used as a prognostic indicator. Differential diagnosis of lung tumors has been studied extensively with both computed tomography (CT) and positron emission tomography (PET). It has been established that FDG-PET is clinically very useful and that its diagnostic accuracy is higher than that of CT. Detection of lymph node or distant metastases in known cancer patients using a whole-body imaging technique with FDG-PET has become a good indication for PET. FDG uptake may be seen in a variety of tissues due to physiological glucose consumption. Also FDG uptake is not specific for cancer. Various types of active inflammation showed FDG uptake to a certain high level. Understanding of the physiological and benign causes of FDG uptake is important for accurate interpretation of FDG-PET. In monitoring radio/chemotherapy, changes in FDG uptake correlate with the number of viable cancer cells, whereas Met is a marker of proliferation. Reduction of FDG uptake is a sensitive marker of viable tissue, preceding necrotic extension and volumetric shrinkage. FDG-PET is useful for the detection of recurrence and for monitoring the therapeutic response of tumor tissues in various cancers, including those of the lung, colon, and head and neck. Thus, PET, particularly with FDG, is effective in monitoring cancer cell viability, and is clinically very useful for the diagnosis and detection of recurrence of lung and other cancers.

Usefulness of a FDG-PET Scan in Assessing Recurrent Gastric Cancer

Purpose: For curative resection of recurrent gastric cancer, it is imperative that there be no unrecognized foci of tumoral disease outside the operation field. PET (positron emission tomography) with FDG (18 fluoro-2 deoxy-D-glucose) is a whole-body imaging technique that exploits the increased rate of glycolysis in tumor cells to detect disease. The authors evaluated the usefulness of FDG-PET in assessing resectability of recurrent gastric cancer. Materials and Methods: Seven patients with recurrent gastric cancer were studied with FDG-PET from December 1998 to October 2000. All FDG-PET images were interpreted in conjunction with conventional diagnostic methods. All imaging results were correlated with the pathological diagnosis and clinical outcome. Results: A final diagnosis of recurrence was obtained at 14 sites in all 7 patients by histology or clinical follow up. Locoregional recurrence, including distant metastasis, developed in 6 of 7 patients and distant recurrence in only one. FDG-PET detected all recurrent sites (5 locoregional and 5 distant) in 5 patients without peritoneal recurrence, but did not detect peritoneal seeding in 2 patients with peritoneal recurrence. The accuracy of FDG-PET in estimating resectability was (5/7), and that of CT and PET together was (6/7). A curative resection could be performed in three of the recurrent patients (2 locoregional and 1 distant recurrence). Conclusion: Our results suggest that FDG-PET may be useful for detecting locoregional and distant recurrence of gastric cancer and for selecting appropriate treatment. However, considering that FDG-PET was limited in detecting peritoneal seeding and determining the exact anatomical extension of tumor, it should be used in conjunction with other anatomical images.

Detection of Lymphoma in Bone Marrow by Whole-Body Positron Emission Tomography

AbstractPositron emission tomography (PET) is a whole-body imaging technique using 18 fluorine-fluorodeoxyglucose (FDG), whose uptake is increased in tumor cells. Published studies have shown PET to be an effective method of staging lymphoma and to be more sensitive than CT at detecting extranodal disease. The purpose of this study was to determine whether the increased marrow uptake of FDG observed in some lymphoma patients during routine staging PET scans represented marrow involvement by disease. PET scans of 50 patients with Hodgkin's (12) and non-Hodgkin's (38) lymphoma were analyzed by three independent observers and the marrow graded as normal or abnormal using a visual grading system. Unilateral iliac crest marrow aspirates and biopsies were performed on all patients. The PET scan and marrow histology agreed in 39 patients (78%), being concordant positive in 13 and concordant negative in 26 patients. In 8 patients the PET scan showed increased FDG uptake but staging biopsy was negative; in 4 of these 8 patients the PET scan showed a normal marrow background with focal FDG “hot spots” distant from the site biopsied. In 3 patients the marrow biopsy specimen was positive but the PET scan normal; 2 of these 3 patients had non-Hodgkin's lymphoma whose malignant cells did not take up FDG at lymph node or marrow disease sites. Therefore, there were only 5 patients (10%) in whom there was a difference between the PET scan and biopsy result which could not be fully explained. Visual interpretation of marrow FDG uptake during whole-body staging PET scans can correctly assess marrow disease status in a high proportion of lymphoma patients. PET has the potential to reduce the need for staging marrow biopsy.

Detection of Lymphoma in Bone Marrow by Whole-Body Positron Emission Tomography

Positron emission tomography (PET) is a whole-body imaging technique using 18 fluorine-fluorodeoxyglucose (FDG), whose uptake is increased in tumor cells. Published studies have shown PET to be an effective method of staging lymphoma and to be more sensitive than CT at detecting extranodal disease. The purpose of this study was to determine whether the increased marrow uptake of FDG observed in some lymphoma patients during routine staging PET scans represented marrow involvement by disease. PET scans of 50 patients with Hodgkin's (12) and non-Hodgkin's (38) lymphoma were analyzed by three independent observers and the marrow graded as normal or abnormal using a visual grading system. Unilateral iliac crest marrow aspirates and biopsies were performed on all patients. The PET scan and marrow histology agreed in 39 patients (78%), being concordant positive in 13 and concordant negative in 26 patients. In 8 patients the PET scan showed increased FDG uptake but staging biopsy was negative; in 4 of these 8 patients the PET scan showed a normal marrow background with focal FDG “hot spots” distant from the site biopsied. In 3 patients the marrow biopsy specimen was positive but the PET scan normal; 2 of these 3 patients had non-Hodgkin's lymphoma whose malignant cells did not take up FDG at lymph node or marrow disease sites. Therefore, there were only 5 patients (10%) in whom there was a difference between the PET scan and biopsy result which could not be fully explained. Visual interpretation of marrow FDG uptake during whole-body staging PET scans can correctly assess marrow disease status in a high proportion of lymphoma patients. PET has the potential to reduce the need for staging marrow biopsy.

The application of positron emission tomographic imaging with fluorodeoxyglucose to the evaluation of breast disease.

Positron emission tomography (PET) is a computer-aided tomographic imaging technique that uses positron-emitting compounds to trace biochemical processes of tissue, and construct images based on them. The authors applied a whole-body PET imaging technique to patients with breast masses or mammographic abnormalities using the isotope 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG), in a clinical trial to evaluate the feasibility of using PET to identify primary breast cancer, axillary lymph node involvement, and systemic metastases, before surgical resection. Fourteen patients have been entered on this study, 10 of whom proved to have breast cancer. Positron emission tomography correctly predicted the nature of 12 of the 14 primary breast lesions, and correctly determined the lymph node status of 11 of the 14 patients. The authors conclude that PET with FDG has potential as a diagnostic modality for detection of primary breast cancer, particularly in the patient with radiodense breasts by conventional mammography, and that it has potential for the preoperative identification of axillary lymph node metastases.

Galactopoietic and mammogenic effects of long-term treatment with bovine growth hormone and thrice daily milking in goats

Starting in mid-lactation, goats were treated daily for 22 weeks with 0.15 mg recombinant bovine GH (bGH)/kg, or an equivalent volume of vehicle. One gland of each goat was milked thrice daily throughout treatment, the other twice daily. Mammary differentiation was studied in biopsy samples obtained before treatment and after 3 and 22 weeks of treatment, by determination of in-vitro synthesis rates of milk constituents and measurement of enzyme activities. Mammary growth was measured using a whole-body imaging technique (magnetic resonance imaging; MRI). bGH caused an immediate and sustained increase in milk yield of approximately 23% overall, whilst the glands milked thrice daily produced approximately 14% more than the control glands milked twice daily. The effects of the combined treatment were additive, but not synergistic. A synergistic effect of the combined treatment resulted in a significant improvement in lactation persistency. A stimulatory effect of milking frequency on mammary enzyme activities was evident only in bGH-treated goats at 3 weeks, but in both groups at 22 weeks. Synthesis rates of casein and lactose were increased at 3 weeks only by the combined treatment. Thus bGH accelerated or augmented the differentiative response to thrice daily milking. Mammary parenchyma volume, estimated by MRI, increased significantly during the first 12 weeks of bGH treatment and remained higher throughout the rest of the treatment period. Cell number was estimated from parenchyma volume and DNA concentration; this decreased significantly in the controls between weeks 1 and 22, but remained constant in the bGH group. In nine of the ten goats, parenchyma volume and cell number increased in the gland milked thrice daily relative to the control gland milked twice daily during the course of the experiment. Thus bGH stimulated growth of the mammary gland over and above that induced by the frequent milking. The absence of any detectable increase in thymidine incorporation suggests that this growth consisted of cellular hypertrophy rather than hyperplasia.

Primary lung cancer: biodistribution and dosimetry of two In-111-labeled monoclonal antibodies.

This study was undertaken to measure the biokinetics and organ dosimetry of indium-111-labeled monoclonal antibodies (MoAbs) with a whole-body gamma camera imaging technique. Twenty patients with primary lung cancer were studied with two different MoAb agents (anti-carcinoembryonic antigen ZCEO25 and antiadenocarcinoma LA20207). Imaging was performed at 1, 24, 72, and 144 hours after injection. Scintigraphic whole-body retention was verified by means of comparison with the results from in vitro counting of excreta. Organ retention was verified in an abdominal phantom. The MoAb cleared slowly from the heart and lungs, the brain and spleen showed no clearance, and the liver showed increased activity over the 6-day period. Dosimetry for ZCE025 showed a dose to the liver of 1.3 rad/mCi (0.36 mGy/MBq); heart, 1.5 rad/mCi (0.40 mGy/MBq); spleen, 1.1 rad/mCi (0.29 mGy/MBq); total body, 0.49 rad/mCi (0.13 mGy/MBq); and testes, 0.39 rad/mCi (0.11 mGy/MBq). The dosimetry for LA20207 was similar.