The combination of positron emission tomography (PET) with magnetic resonance imaging (MRI) has been the subject of several studies in recent years. Positron emission tomography is the most sensitive and specific imaging modality in the detection of metabolic changes, but presents limited spatial resolution. On the other hand, MRI presents a significant spatial resolution, besides evaluating soft tissues signal intensity with excellent contrast resolution. The present iconographic essay is aimed at demonstrating the potential clinical application of PET/MRI coregistration. The studies were performed in a dedicated PET unit with 18F-fluorodeoxyglucose (FDG) as radiopharmaceutical and coregistered with 1.5 T or 3 T brain MRI. The brain images fusion software presents an already well-established accuracy, so a significant synergy between a functional PET study and an excellent MRI anatomical detail is achieved. The most attractive clinical applications of this approach are the following: epileptogenic zone assessment in patients refractory to drug therapy, identification of patients with cognitive impairment at higher risk for progression to dementia and differentiation of dementias and Parkinsonian syndromes.

Keywords: Fluorodeoxyglucose, FDG, Positron emission tomography, PET, Magnetic resonance imaging, Fusion, Clinical neurology

OBJECTIVE: The present study evaluated the doses received by companions who had shared therapeutic rooms with patients undergoing treatment with 131-iodine (131I). The results were compared with the limits established by the Brazilian radiation protection regulatory standard. MATERIALS AND METHODS: Six pairs of persons (a patient and a companion sharing a same therapeutic room) were evaluated. Still, other 23 experiments were accomplished with a phantom replacing the companion. The therapeutic 131I activities given to the patients corresponded to 3700 MBq or 5550 MBq. Powdered lithium fluoride thermoluminescent dosimeters doped with magnesium, titanium and sodium were utilized for evaluating the doses. RESULTS: The results demonstrate that a person sharing a same therapeutic room, for two days, with a patient who had been given 3700 MBq or 5550 MBq of 131I, according to radioprotection recommendations, is exposed to a mean dose of (0.51 ± 0.02) mSv for a 99% confidence level. CONCLUSION: According to the Brazilian radiation protection standards there is no impediment for a person to accompany a nuclear medicine patient who has been given 3700 MBq or 5550 MBq of 131I during the patient stay in the therapeutic room.

Keywords: Nuclear medicine, Companion, Therapeutic room, Thermoluminescent dosimeter

OBJECTIVE: To study the utility of diffusion-weighted magnetic resonance imaging in the differentiation between benign and malignant breast lesions. MATERIALS AND METHODS: Forty-five women (mean age, 46.1 years) with 52 focal breast lesions underwent diffusionweighted magnetic resonance imaging. The calculation of apparent diffusion coefficient (ADC) was based on the ADC map reflecting five b values (0, 250, 500, 750, and 1000 s/mm²). The mean ADC value of each lesion was correlated with imaging findings and histopathologic results. Cutoff ADC, sensitivity and specificity of diffusion-weighted imaging in the differentiation between benign and malignant lesions were calculated. P < 0.05 was considered as statistically significant. RESULTS: The mean ADC was significantly lower for malignant lesions (0.92 ± 0.26 × 10-3 mm²/s) as compared with benign lesions (1.50 ± 0.34 × 10-3 mm²/s) (P < 0.0001). Diffusion-weighted imaging showed high sensitivity and specificity (both, 92.3%) in the differentiation between benign and malignant lesions. CONCLUSION: Diffusion-weighted imaging is a potential resource as an adjuvant to breast magnetic resonance imaging to differentiate benign from malignant lesions. Such sequence can be easily added to the standard breast magnetic resonance imaging protocol, without implying any significant increase in examination time.

Keywords: Breast cancer, Diffusion-weighted imaging, Magnetic resonance imaging

OBJECTIVE: The present study was aimed at developing and delivering a course in the modality "Internet-conducted distance education". MATERIALS AND METHODS: The theme "Sentinel lymph node, prevention, early diagnosis and biopsy - a new technique for approaching breast cancer" was utilized as an application model, and the didactic material for distance-learning was targeted to a selected audience of physicians involved in the treatment of breast cancer. The course was structured in a virtual learning environment, allowing interaction among participating students. RESULTS: The coursework took place over a 12-week period. Nine gynecologists with at least eight years of professional experience participated in some way in the course, but only two of them accomplished exercises and interacted. In the distance-education modality, the course reached eight cities in four Brazilian states. A full engagement did not occur, although most of participants have remained until the end of the course. Possibly, there was a lack of motivation. CONCLUSION: The results demonstrate that it is necessary to break the barriers to the culture related to this form of learning. A pro-active participation of the coordinator is essential for integrating and mobilizing the participants.

Keywords: Continuing medical education, Telemedicine, Distance education, Internet, Course management system

The authors perform a revisional and iconographic study of the lacrimal system by means of radiological methods, namely, conventional radiography, linear tomography, computed tomography and magnetic resonance imaging. Image methods are essential to define diagnosis and therapy, considering that besides demonstrating alterations of the lacrimal system, they may indicate the patients with better prognosis associated with the surgical approach. Considering the lower cost, lower radiation dose, low rate of complications, and level of information that can be obtained dacryocystography by means of linear tomography is recommended as the initial investigation method.

Keywords: Dacryocystography, Lacrimal system, Obstruction of the lacrimal system

OBJECTIVE: To use skeletal scintigraphy to detect mandibular growth through the analysis of bone metabolism in individuals with normal craniofacial growth, and to compare the findings with those seen in individuals with excessive craniofacial growth. MATERIALS AND METHODS: Forty-seven male and female patients between 18 to 28 years of age were divided in two groups - class I, control (n = 13), and class III, case (n = 34). Images were obtained two hours after intravenous injection of 99mTc-MDP (200 µCi/kg). Right and left side views of the mandible were obtained as well as a posterior view of the lumbar spine. The count rate was determined by the mean values of the count of the condyles and of the fourth lumbar vertebra, using a total of 300,000 counts. RESULTS: No asymmetrical condyle uptake was observed in both groups, and in spite of the absence of statistically significant differences, the mean condylar uptake values were higher in class III group. CONCLUSION: The increased mean uptake indicated higher condylar bone metabolism in class III individuals suggesting residual mandibular growth. Further studies are presently ongoing to increase our sample size.

Keywords: Bone scintigraphy, Mandibular condyle, Mandibular growth, Temporomandibular joint

Renal allograft acute rejection must be promptly diagnosed since its reversibility is related to the readiness in which treatment is initiated. The aim of this study was: 1) to establish a quantitative method to evaluate kidney rejection and acute tubular necrosis (ATN); 2) to assess the potential role of 99mTc-mononuclear leukocytes scintigraphy in the diagnosis of renal rejection and differential diagnosis of ATN. One hundred and sixty studies were performed in 80 renal transplant patients at the first and fifth day after transplantation. Autologous cells were used for labeling. Images were obtained at 30 minutes, 3 hours and 24 hours after intravenous administration of 444 MBq (12 mCi) of labeled cells. There was abnormal labeled cells uptake in 27 of 31 cases of rejection and in 6 of 8 cases of ATN. The results of each patient were compared with clinical findings. Doppler scanning detected 18 of 31 cases of rejection. Rejection diagnosis sensitivity and specificity rates using scintigraphy were 87.1% and 100%, respectively, and 58.1% and 100%, respectively using ultrasound. Renal biopsy was performed in eight patients which demonstrated seven cases of rejection and one case of ATN. These results suggest that 99mTc-mononuclear leukocytes imaging may be useful in the early diagnosis of rejection and in the differential diagnosis of ATN.

Keywords: 99mTc-mononuclear leukocytes, Renal allograft, Rejection, Diagnosis

The main objective of this study is to implement an impartial and efficient inspection method for a correct and secure use of ionizing radiation in nuclear medicine. The radiological protection model was tested in 113 nuclear medicine services (NMS) all over Brazil, following a biannual analysis schedule (1996, 1998, 2000 and 2002). In the analytical process, we adopted the methodology of assigning different importance levels to each of 82 features, based on the risk factors established by the "Comissão Nacional de Energia Nuclear" (CNEN) and on the International Atomic Energy Agency (IAEA) recommendations. A feature was considered a radioprotection fault when in nonconformity with the rules mentioned above, and was imparted a grade. The sum of those grades, classified the NMS in one of the three different ranges, as follows: operating without restriction - 100 points and below; operating with restriction - between 100 and 300 points; temporary shutdown - above 300 points. Permission for the second group to carry on operation should be attached to a defined and restricted period of time (6 to 12 months), considered enough for the NMS to solve the problems and submit to a new evaluation. The NMS's classified in the third group are supposed to go back into operation only after compliance with all the pending radioprotection requirements. Until the next regular evaluation, a multiplication factor 2n was applied to the recalcitrant NMS's, where n is the number of unwilling occurrences. The previous establishment of those items of radioprotection, with their respective grades, excluded subjective and personal values in the judgement and technical evaluation of the institutions.

Keywords: Nuclear medicine, Radiation protection, Rules, Inspection

The aim of this study was to identify the sentinel node by periareolar injection of the radiopharmaceutical in four points, regardless of tumor topography. The sentinel node biopsy reduces morbidity in axillary staging. Fifty-seven sentinel node biopsies were prospectively performed in two groups: group A (25 patients) and group B (32 patients). The peritumoral injection technique was used in group A and the new injection technique in four points was used in group B. The sentinel node biopsies were studied by imprint cytology and hematoxilin and eosin staining followed by axillary lymph node dissection in all patients of group A and only in the positive cases of group B. In group A, 88% (22/25) of the sentinel nodes were identified. There was no false negative case; the sensibility and specificity were of 100%. In group B, 96% (31/32) of sentinel nodes were identified and the status of the axillary lymph nodes showed a predictive positive value of 100%. The number of sentinel nodes varied from 1 to 7, mode of 1 and median of 2.7. The hotspot area was 10 to 100 times the background radiation. The periareolar injection in four points seems to be a good lymphatic mapping method for identification of the sentinel node. We suggest the standardization of this site for injections to identify the sentinel node, although further studies to confirm these findings are necessary.

Keywords: Breast cancer, Sentinel node, Lymphoscintigraphy

Occlusion of the iliac arteries is a common disease. Several surgical options are available to treat them, such as aorto-bifemoral bypass graft, cross femoro-femoral bypass, endoprosthesis implants and others. Aorto-bifemoral bypass graft is considered the treatment that provides the best results. Endovascular treatment for occlusion of the iliac arteries provides high success rates and low incidence of complications. Twenty-four patients, aged between 39 and 82 years (mean 61 years), were submitted to this treatment. Intermittent claudication and critical ischemia were the indications in 19 and 5 patients, respectively. The most common risk factor was smoking (19 patients). The technical success rate of iliac artery recanalization was 91.7% and the patency rate after one year was 71%. The good results achieved with percutaneous recanalization and stenting of occluded iliac arteries, which presents low morbidity and mortality rates, suggest that this procedure should be included among the therapeutic options for the treatment of iliac arteries occlusion.

Keywords: Iliac arteries, Recanalization, Endoprosthesis

Dynamic renal scintigraphy allows the diagnosis of complications in patients submitted to organ transplantation, such as perfusion abnormalities, acute tubular necrosis and rejection. In this study we employed 99mTc-DTPA scintigraphy to study patients submitted to kidney transplantation. The results obtained and the clinical findings were conjunctly analyzed in order to detect graft rejection or other complications. The type of immunosuppressive scheme used was also correlated with the observed complications. Fifty-five patients submitted to kidney transplantation from 1989 to 1999 were evaluated. All patients with nephrotoxicity received a 3-drug immunosuppressive scheme. In this study, acute rejection was the most frequent complication (40.4%) observed following transplantation. Thirteen of 15 recipients of cadaveric kidney grafts presented acute tubular necrosis. Only one false-positive case was observed when scintigraphy and clinical findings were not concordant. We suggest carrying out renal scintigraphy to follow-up post-transplantation patients.

Keywords: Dynamic renal scintigraphy, 99mTc-DTPA, Kidney transplantation, Immunosuppression

The present study was aimed at analyzing civil liability for medical errors specifically for a radiologist’s errors in the mammographic diagnosis of breast cancer. As examples, Court decisions were analyzed with the aim of showing the understanding of the Brazilian Courts of Law, among them the Supreme Federal Court that is responsible for reviewing, on appeal, judicial decisions affronting the Brazilian Constitution, as well as the Superior Court of Justice, that is competent to judge on appeals against decisions violating Federal Laws. The reviewed material demonstrates the Courts’ view on the subject discussed on the present article, describing the consequences of radiologists’ and radiological centers’ errors in the sphere of the civil law that establishes monetary indemnity as a consequence of the existence of civil liability. That is to say that the duty to indemnify arises from the testifying of the existence of civil liability. Thus, once the civil liability is removed, the duty to indemnify comes to an end. Indemnity should not be confused with civil liability; the latter is the foundation of the former.

Keywords: Medical error; Mammography, Breast cancer; Civil liability.

OBJECTIVE: To evaluate the utility of a new multimodal image-guided intervention technique to detect epileptogenic areas with a gamma probe as compared with intraoperative electrocorticography. MATERIALS AND METHODS: Two symptomatic patients with refractory epilepsy underwent magnetic resonance imaging, video-electroencephalography, brain SPECT scan, neuropsychological evaluation and were submitted to gamma probe-assisted surgery. RESULTS: In patient 1, maximum radioactive count was initially observed on the temporal gyrus at about 3.5 cm posteriorly to the tip of the left temporal lobe. After corticotomy, the gamma probe indicated maximum count at the head of the hippocampus, in agreement with the findings of intraoperative electrocorticography. In patient 2, maximum count was observed in the occipital region at the transition between the temporal and parietal lobes (right hemisphere). During the surgery, the area of epileptogenic activity mapped at electrocorticography was also delimited, demarcated, and compared with the gamma probe findings. After lesionectomy, new radioactive counts were performed both in the patients and on the surgical specimens (ex-vivo). CONCLUSION: The comparison between intraoperative electrocorticography and gamma probe-assisted surgery showed similarity of both methods. The advantages of gamma probe include: noninvasiveness, low cost and capacity to demonstrate decrease in the radioactive activity at the site of excision after lesionectomy.

Keywords: Radioguided surgery; Epilepsy; Gamma probe; Electrocorticography; Brain SPECT.