SPNsim: A database of simulated solitary pulmonary nodule PET/CT images facilitating computer aided diagnosis.

The aim of the present work was to design and develop a database of simulated solitary pulmonary nodules (SPN) in pairs of computed tomography (CT) and positron emission tomography (PET) images, using Monte Carlo (MC) simulation methods. We have developed an SPN image modeling pipeline to feed the database entitled SPNsim. The database is web-accessible and it is contains two subsets of simulated PET/CT SPN images. The first subset is currently composed of 1000 cases containing pairs of the transaxial CT and the corresponding PET slice with various types of simulated SPNs, presented as individual records. The second subset contains pairs of the transaxial CT and the corresponding PET slice of simulated SPNs, presenting cases of graded difficulty in diagnosis. The users of the database will have the ability to set queries in order to retrieve cases with certain characteristics, as well as characterized image sets. All images are freely available and may be downloaded from the website. SPNsim provides a useful reference data set for training and evaluation of computer aided detection (CAD) and diagnosis (CADx) systems focusing on SPN.

Patient-specific dosimetry in peptide receptor radionuclide therapy: a clinical review.

Neuroendocrine tumours (NETs) belong to a relatively rare class of neoplasms. Nonetheless, their prevalence has increased significantly during the last decades. Peptide receptor radionuclide therapy (PRRT) is a relatively new treatment approach for inoperable or metastasised NETs. The therapeutic effect is based on the binding of radiolabelled somatostatin analogue peptides with NETs' somatostatin receptors, resulting in internal irradiation of tumours. Pre-therapeutic patient-specific dosimetry is essential to ensure that a treatment course has high levels of safety and efficacy. This paper reviews the methods applied for PRRT dosimetry, as well as the dosimetric results presented in the literature. Focus is given on data concerning the therapeutic somatostatin analogue radiopeptides (111)In-[DTPA(0),D-Phe(1)]-octreotide ((111)In-DTPA-octreotide), (90)Y-[DOTA(0),Tyr(3)]-octreotide ((90)Y-DOTATOC) and (177)Lu-[DOTA(0),Tyr(3),Thr(8)]-octreotide ((177)Lu-DOTATATE). Following the Medical Internal Radiation Dose (MIRD) Committee formalism, dosimetric analysis demonstrates large interpatient variability in tumour and organ uptake, with kidneys and bone marrow being the critical organs. The results are dependent on the image acquisition and processing protocol, as well as the dosimetric imaging radiopharmaceutical.

Radiation exposure to caregivers from patients undergoing common radionuclide therapies: a review.

The contribution of radionuclide therapies (RNTs) to effective patient treatment is widely appreciated. The administration of high doses has necessitated investigating the potential radiation hazard to caregivers from patients undergoing RNTs. This work aimed to review the literature regarding measured effective doses to caregivers from such patients. The main selection criterion was the presence of real radiation exposure measurements. The results were categorised according to the treatment protocol and dose parameters. Analysis of the collected data demonstrated that the measured effective dose values were within the dose constraints defined by the International Commission on Radiological Protection, provided that the radiation protection instructions were followed by both patients and caregivers. In conclusion, the radiation risk for caregivers was almost negligible. In this context, treatments could be administered more often on an outpatient basis, once cost-effectiveness criteria were established and radiation protection training and procedures were appropriately applied.

The education and training of clinical medical physicists in 25 European, 2 North American and 2 Australasian countries: similarities and differences.

PURPOSE: The clinical medical physicist is part of a team responsible for safe and competent provision of radiation-based diagnostic examinations and therapeutic practices. To ensure that the physicist can provide an adequate service, sufficient education and training is indispensable. The aim of this study is to provide a structured description of the present status of the clinical medical physicist education and training framework in 25 European, 2 North American and 2 Australasian countries. METHODS: For this study, data collection was based on a questionnaire prepared by the European Federation of Organizations in Medical Physics (EFOMP) and filled-in either by the corresponding scientific societies-organizations or by the authors. RESULTS: In the majority of cases, a qualified medical physicist should have an MSc in medical physics and 1-3 years of clinical experience. Education and training takes place in both universities and hospitals and the total duration of the programs ranges from 2.5 to 9 years. In 56% of all European countries, it is mandatory to hold a diploma or license to work as a medical physicist, the situation being similar in Australasian and 4 states of USA. Generally, there are national registers of medical physicists with inclusion on the register being voluntary. There are renewal mechanisms in the registers usually based on a Continuing Professional Development (CPD) system. CONCLUSIONS: In conclusion, a common policy is followed in general, on topics concerning education and training as well as the practice of the medical physicist profession, notwithstanding the presence of a few differences.

Prediction of successful discectomy using MRI quantitation of dural sac and herniated disc dimensions.

OBJECTIVE: To evaluate the ability of magnetic resonance imaging (MRI) quantitation of disc prolapse and dural sac to identify those who would benefit from discectomy. METHODS: Thirty consecutive patients with disc herniation and leg pain who had MRI of lumbar spine and subsequently underwent discectomy were prospectively enrolled and compared with 30 controls. The anteroposterior (AP) diameter and the cross-sectional area of disc prolapse and of dural sac were measured. The ratios of AP diameters and cross-sectional areas were calculated. The measurements were correlated with the relief of symptoms based on a visual analogue scale assessment preoperatively and 1 week postoperatively. RESULTS: All patients preoperatively had a pain score of seven or higher (mean +/- SD = 7.9 +/- 0.3) and postoperatively a score of < or = 2(mean +/- SD = 1.1 +/- 0.2). The AP diameter of disc prolapse and the ratio of AP diameters demonstrated the highest sensitivity and specificity: an AP diameter of 3.3 mm was 99% sensitive and specific and a ratio of the AP diameters of 0.37 was 100% sensitive and 99% specific. CONCLUSION: Quantitative measurements of MRI can improve significantly the ability to identify the patients who would benefit from discectomy.

Pancreatic cancer's initial presentation: back pain due to osteoblastic bone metastasis.

Pancreatic cancer may cause osteolytic metastases, but the osteoblastic ones are extremely rare. In addition, it almost always presents with symptoms related to the invasion of the structures in the abdomen. Symptoms from bone metastases are rare and, if seen, are in the late phase of the course. We present a case of cancer of the body of the pancreas, which presented with severe back pain due to an osteoblastic lesion to L3 vertebra. Biopsy of the vertebra led to the diagnosis. Radiographs, computed tomography, magnetic resonance and scintigraphic images as well as pathology slices are shown. The present case raises the issue that pancreatic cancer, as a cause of an osteolytic bone lesion, should not be overlooked in an unknown primary investigation.

Signs of striatal dopamine transporter density increase in association with improvement of tardive dyskinesia in a patient with schizophrenia, as demonstrated by a DAT scan.

The imaging of the dopamine transporter could demonstrate the implication of dopaminergic pathway in the appearance of tardive dyskinesia. We report a case with psychotic and tardive dyskinesia symptoms. A DAT scan showed decreased dopamine transporter uptake in the area of brain's basal gaglia. A trial with quetiapine improved both psychotic and TD symptoms while a second DAT scan showed improvement status. We conclude that increased dopamine transporter uptake seemed to associate with the improvement of TD.

Efficacy and cost-effectiveness of cell saving blood autotransfusion in adult lumbar fusion.

The objective of this study was to explore the use of cell saver blood autotransfusion in spinal surgery and to evaluate the efficacy and cost-effectiveness of cell saver blood autotransfusion during lumbar spine fusion in adults. Specific indications for the use of cell saver in adult lumbar fusion surgery have not yet been clearly determined. A total of 50 consecutive candidates for posterolateral fusion with internal fixation were prospectively randomized into either receiving perioperatively cell saving autotransfusion (Group A: 25 patients) or not (Group B: 25 patients). The use of cell saving technique did not exclude the use of allogenic blood transfusion. Surgical indications were spinal stenosis, spondylolisthesis, adolescent idiopathic scoliosis, degenerative scoliosis and fractures. Medical and financial data were recorded. A cost-analysis was performed. Patients in Group A received 880 +/- 216 mL from cell saver and 175 +/- 202 mL allogenic blood. The patients in Group B received 908 +/- 244 mL allogenic blood. Blood volumes data collected were expressed in mean +/- SD values. The cost of blood transfusion in Group A was 995 +/-euro447 per patient and 1220 +/- 269 in Group B (P < 0.05). In elective lumbar fusion blood requirements can be satisfied with the use of autotransfusion. The use of cell saver appears to be useful and cost-effective during most elective lumbar fusions.

Women with high exercise tolerance and the role of myocardial perfusion imaging.

BACKGROUND: Myocardial perfusion imaging (MPI) provides incremental diagnostic and prognostic information, even in patients with high exercise tolerance. HYPOTHESIS: Myocardial perfusion imaging provides significant diagnostic value, specifically in women with high exercise tolerance. METHODS: Our study population consisted of all women who underwent exercise MPI in our Department from January 1992 to June 1996 and reached at least Stage IV in the Bruce protocol. Patients were divided into those with known and those with possible coronary artery disease (CAD). All patients were followed for 3 years from the performance of MPI. RESULTS: Of 4,803 women who underwent myocardial perfusion imaging, 3,183 had exercise stressing, and of those, 311 reached at least Stage IV in the Bruce protocol. Of these 311 MPI scans, only 23 (7.4%) were abnormal (reversible, fixed, or mixed) and the remaining 288 (92.6%) were normal. Of the 82 patients with known CAD, 13 (15.8%) had an abnormal MPI, while only 10 (4.4%) of the 229 patients with possible CAD. No myocardial infarction or cardiac death occurred within 3 years; one patient with normal MPI needed revascularization. CONCLUSION: In women with high exercise tolerance, especially in those without already known CAD, the yield of MPI is very low. Women with high exercise tolerance have an excellent prognosis.

Overestimation of the LVEF by quantitative gated SPECT in simulated left ventricles.

UNLABELLED: During routine myocardial perfusion imaging, a common observation is that patients with normal cardiac function and small hearts, in particular small women, have higher left ventricular ejection fractions (LVEFs), as measured by quantitative gated SPECT (QGS) software, than anticipated, often markedly so. The goal of this project was to determine if the QGS LVEF varies with the change in end-diastolic left ventricular volume (EDV) and in particular to verify that the clinically observed phenomenon of falsely elevated QGS LVEF in patients with small hearts is actually occurring. METHODS: A series of mathematically defined left ventricles (LVs) was produced by varying the EDV and targeted LVEF (tLVEF). These were created using concentric hemiellipsoids with nine different EDVs. The tLVEF was varied from 15% to 75% by 5% increments for a total of 13 different ejection fractions. These datasets were then smoothed, creating a total of 234 sets. The smoothed and unsmoothed images were then processed using QGS software. The LVEFs and EDVs were recorded. RESULTS: For lower LVEFs the agreement between the QGS LVEF and the tLVEF is good. A marked overestimation occurs when the EDVs are low and the ejection fractions are in the higher range. This effect is greater in the smoothed images. CONCLUSION: An artifactual increase in the LVEF can occur when measurements are made with the QGS software. These data argue against using QGS LVEF for monitoring the LVEF in patients with small hearts. Our data imply that a mildly decreased LVEF may still appear to be in the normal range when measured by QGS software.

The role of radionuclides in primary musculoskeletal tumors beyond the 'bone scan'.

Radionuclides represent a means of functional imaging, which is able to reflect the metabolic state of tissues. Recently developed radiotracers and older radiotracers with newer applications, imaged through single photon emission computed tomography (SPECT) and positron emission tomography (PET), can provide significant information in the diagnosis, grading, therapy response or recurrence of primary musculoskeletal tumors. The unique ability of these radiotracers to demonstrate non-invasively the efflux pump rate, which is a common reason of therapy failure, as well as the metabolic and proliferative rates of the tumors should be a powerful tool in the orthopaedic oncology in the evaluation of musculoskeletal tumors.

Indium-111 leukocyte scintigraphy in suspected bowel ischemia.

OBJECTIVE: The purpose of this study was to evaluate the utility of indium-111 leukocyte (In-111 WBC) scintigraphy in a large number of patients with suspected bowel ischemia. METHODS: All patients who underwent In-111 WBC scintigraphy for possible bowel ischemia over a 4-yr period and had subsequent endoscopic or surgical biopsy were retrospectively evaluated. Early (1-4 h postinjection) and late (18-24 h postinjection) images were obtained. Any study with tracer activity in the bowel on early or late images was considered positive for bowel ischemia. RESULTS: Fifty-nine patients were included in the analysis. In-111 WBC scintigraphy detected 23 of 24 cases of bowel ischemia (sensitivity = 96%). Of 35 cases without ischemia, 16 had a negative In-111 WBC scintiscan (specificity = 46%). Negative and positive predictive values for the diagnosis of bowel ischemia were 94% and 55%, respectively. Of the 19 cases without bowel ischemia and a positive scintiscan, 15 had another intraabdominal process responsible for the patients' symptomatology. CONCLUSIONS: In-111 WBC scintigraphy is a highly sensitive diagnostic tool for bowel ischemia. A normal In-111 WBC scintiscan strongly suggests that this disease is not present.

Gating of myocardial perfusion imaging for the identification of artifacts: is it useful for experienced physicians?

Gating of myocardial perfusion imaging helps to differentiate artifacts from perfusion defects. We used this technique to evaluate the impact of routine gating on the interpretation of results by physicians experienced in this field. We studied, prospectively, 270 consecutive patients (161 men and 109 women) who underwent gated myocardial perfusion imaging. Single-photon emission-computed tomography was performed to evaluate myocardial perfusion in patients at rest and after stress, using technetium-99m sestamibi and post-stress gating. Participating physicians interpreted each study and indicated a confidence level for the interpretation. Initially, these opinions were formed on the basis of static slices alone and subsequently, with the addition of gating information. The impact of gating was evaluated by the number of studies in which gating led to a change in interpretation from normal to abnormal or vice versa, or from borderline to definite. The interpretation was changed from abnormal to normal or vice versa in 10 studies (3.7%) and from borderline to definite in 3 (1.1%). In 37 studies (13. 7%), the confidence level was increased from confident to very confident with no change in interpretation. We conclude that routine gating of every myocardial perfusion imaging study for the identification of artifacts is of low value for physicians experienced in interpreting such studies. Although gating frequently increases the confidence level, it seldom leads to a change in interpretation. Specific subgroups of patients who would benefit from gating should be identified.

Hepatobiliary scintigraphy is superior to abdominal ultrasonography in suspected acute cholecystitis.

BACKGROUND: Hepatobiliary scintigraphy is a very accurate test in the diagnosis of acute cholecystitis. However, ultrasonography is extensively used for the diagnosis of this disease. In this study, we directly compare the diagnostic accuracy of these techniques for acute cholecystitis. MATERIALS AND METHODS: The diagnostic accuracy of scintigraphy and ultrasonography was evaluated in 107 consecutive patients with suspected acute cholecystitis who underwent both imaging modalities within one day. The incremental diagnostic value of each modality was determined. RESULTS: The sensitivity, specificity, positive and negative predictive values, and accuracy for the diagnosis of acute cholecystitis in the entire cohort were superior for scintigraphy compared with ultrasonography. The accuracy was 92% for scintigraphy and 77% for ultrasonography. Similarly, if only surgically treated patients were considered, the accuracy of scintigraphy was 91% versus 61% for ultrasonography. The diagnostic value of scintigraphy for the entire cohort was significantly superior to ultrasonography (global, chi(2) = 58.1 vs 9.7, respectively); the addition of the information derived from the latter did not further improve the diagnostic value of scintigraphy (global, chi(2) = 58.2). CONCLUSIONS: Hepatobiliary scintigraphy has superior diagnostic accuracy for acute cholecystitis compared with ultrasonography. The addition of ultrasonography does not further improve the diagnostic accuracy of scintigraphy alone.

The significance of incidental noncardiac findings in Tc-99m sestamibi myocardial perfusion imaging: illustrated by a case.

Technetium 99m sestamibi is widely used in the evaluation of myocardial perfusion imaging. Although the aim of such imaging is cardiac evaluation, numerous other organs are included in the imaging field. Failure to identify incidental abnormal findings in these organs delays diagnosis and treatment. In common with other radiopharmaceutical agents, technetium 99m sestamibi is distributed throughout the body and accumulates in multiple tissues. When interpreting studies that involve this radiotracer, the physician must be aware of its physiologic distribution, in order to recognize abnormal uptake. We present an illustrative case in which areas of decreased tracer activity were noted incidentally during the evaluation of unprocessed single photon emission computed tomography data. These findings were due to metastasis of colon cancer to the liver.

The predominant form of non-toxic goiter in Greece is now autoimmune thyroiditis.

Endemic non-toxic goiter (NTG) in Greece has been attributed primarily to iodine deficiency. Thirty years ago about 60% of the prepubertal boys and girls examined in endemic goiter regions presented with NTG and among them thyroid autoimmunity was rarely detected. Although iodine supplementation has corrected this deficiency during the past 30 years, new cases of NTG still appear. To evaluate the prevalence and type of NTG and the effect of iodine supplementation on them in Greece at present, we performed two cross-sectional clinical studies and a retrospective pathology one: (i) thyroid gland volume and urinary iodine excretion (UIE) were assessed in a representative sample of 1213 schoolchildren from previously endemic and non-endemic regions; (ii) serum thyroxine, tri-iodothyronine, TSH, thyroid autoantibodies (AAB) (anti-thyroid peroxidase and anti-thyroglobulin antibodies) and UIE (in 60 patients) were measured in 300 consecutive patients with NTG from Athens and Heraklion; and (iii) we compared the prevalence of autoimmunity among fine needle aspiration smears of benign thyroid pathologies performed by the same pathologist between 1985 and 1986 (975 cases) and between 1994 and 1995 (2702 cases). We found that 12. 5% of the schoolchildren examined in regions with a previous history of endemic goiter had NTG, whereas this percentage was only 1.7% in areas without such a history. In Athens (61.6%) and Heraklion (58. 5%) a substantial number of NTG patients were AAB positive and biochemically hypothyroid. UIE in Athens did not differ between patients with autoimmune goiter (ATG) and simple goiter. The prevalence of autoimmune stigmata in pathology smears has increased from 5.94% (years 1985-1986) to 13.91% (years 1994-1995) (P<0.05). We conclude that: (i) the persistence of endemic goiter in regional foci despite iodine deficiency correction suggests a possible role for a naturally occurring goitrogen; (ii) ATG is the predominant form of NTG in Greece nowadays; and (iii) the five-fold decrease in the prevalence of NTG during the past 30 years followed by the increase of ATG may support the relative character of the latter.