Single photon emission computed tomography (SPECT) in neurocysticercosis

Neurocysticercosis (NC) is a parasitic infectious disease caused by Taenia solium eggs that set in the brain. Its incidence is increasing both in the developing and the developed world, as a result of low economical and hygiene levels and immigration, respectively. Clinical manifestation of disease varies from no symptoms to epilepsy, increased intra-cranial pressure, arachnoiditis and dementia. In order to evaluate function (perfusion) of affected brains, we studied 40 patients (21 females and 19 males, 19-71 yo) by means of SPECT (ECD, ethyl cysteinate dimer, labelled with 99mTc) and with and without contrast CT. SPECT studies were all abnormal. No difference was noted between active and inactive disease. Two SPECT patterns were noted: a) several areas of focally reduced uptake, resulting from coalescent and big lesions and large destruction of brain tissue (small, isolated and symmetric cysts seen in CT were missed by SPECT); b) diffuse atrophy with reduction of the tracer uptake, associated with ventricle dilatation, corresponding to the cases where ventricular NC was important. Interestingly, we noted diffuse hypoperfusion, with the scintigraphic pattern of atrophy in 5 cases of massive parenchymal infection; in such cases, CT signs of atrophy were clearly less prominent. The first scintigraphic aspect can be explained by the destruction of large areas of brain, which produces focal absence of perfusion; generalised vasculitis and the destruction of large portions of brain tissue could explain the difference noted between the SPECT and the CT aspects in the 5 cases of massive parenchimal infection, and this may be interesting for prognosis. Dilatation of ventricles and Sylvian fissures were interestingly prominent in SPECT. SPECT may be of great value to evaluate brain perfusion in NC

The velocity of a radioactive bolus in the oesophagus evaluated by means of an image segmentation algorithm

Classical scintigraphic evaluation of a radioactive bolus through the oesophagus is based on regions of interest and time/activity curves, which only gives information about the total time required for it to cross the organ. Instantaneous parameters can be obtained if the exact position (centroid) of the bolus is known. For that, one needs to know the co-ordinates of the centre of mass of the bolus radioactivity distribution. From this, one can obtain velocity at each time. Obtaining such a new parameter would be important, to try to determine whether the anatomical differences among the 3 thirds of the oesophagus have a functional correspondence or not. We have studied 5 normal volunteers (4 males, 1 female, 33-68 yo). Each volunteer swallowed (unique swallowing) 40 MBq of 99mTc-phytate in 10 ml water. Eighty frames (0.3 sec) were acquired in a scintillation camera. External marks were used to separate the pharynx from the oesophagus. Images were transformed into bitmap by means of a Sophy Medical processing module and analysed by means of the algorithm, which determines the co-ordinates of the centroid (horizontal and vertical) for each frame and instant velocities through the organ. Different velocities were found in typical evaluations. Curves representing the different positions of the bolus C and the correspondent different Vs were obtained. Different velocities of the bolus were detected during the pharyngeal phase, and proximal, mid and distal parts of the oesophagus. Larger studies are necessary, but it seems that the velocity of a radioactive bolus changes in the different parts of the oesophagus. It is reasonable to say that there is a functional correspondence to the anatomical differences in the organ

Nuclear medicine in tropical disease: an overview

Leprosy is an infectious granulomatous disease. Incidence is again increasing and millions of people are affected in the world. Ga-67 scintigraphy is a good tool to identify active disease; bone scintigraphy is useful in the evaluation of mutilation and 99mTc-DTPA is good to evaluate kidney function. Paracoccidioidomycosis is a deep mycosis that affects nearly all organs. The following scintigraphic exams are useful to evaluate such patients: Ga-67, bone scintigraphy, liver / spleen / bone marrow scintigraphy, 99mTc-DISIDA scintigraphy, lymphoscintigraphy. Mycetoma is bone and soft tissue mycosis and gallim-67 and bone studies are very useful for the detectio of active disease. Tuberculosis is the most well studied tropical disease and dozens of radiopharmaceuticals and techniques were described to evaluate such patients. Jorge Lobo's disease is a rare mycosis that affects mainly indians from the Amazon region and gallium-67 was shown to accumulate in active disease. Neurocysticercosis is spread worldwide and brain SPECT (99mTc-ECD or 99mTc-HMPAO) is a very good tool for the functional evaluation of the disease. Patients suffering from Cutaneous and mucous leishmaniosis may benefit from Gallium-67 scintigraphy. Chagas' disease may affect the heart and/or the digestive tract and several scintigraphic exams may be helpful in the evaluation of such cases (gated blood pool, heart perfusion tests, pharyngeal transit tests, gastric emptying tests, intestinal transit tests, hepato-billiary scintigraphy, among others). Scintigraphy should be more largely used in the functional evaluation of organs and systems of patients affected by topical diseases

Proposal for a compputer program for 99m Tc-DTPA alveolar capillary clearance study

Os radioaerossóis e a cintilografia de ventilaçäo tem papeis bem definidos na rotina medica nuclear. Estudos sobre o clearance alveolo-capilar de tecnécio-99m marcando o ácido dietileno triamino penta-acético (99mTc-DPTA) permitem um diagnóstico precoce, ao menos presuntivo, de infecçöes pulmonares oportunistas, com uma sensibilidade maior que a dos estudos convencionais. Nós desenvolvemos um programa no computador acoplado à câmara de cintilaçäo para processar as imagens adquiridas, resultando em modo rápido e eficiente para quantificaçäo do clearance alveolo-capilar. Realizamos, a título de ilustraçäo, um teste clínico em um voluntário (35 anos, fumante, normal), que nos mostrou ser o programa adequado do ponto de vista de processamento. Adicionalmente, os resultados (pulmäo direito: 2,22 por cento/min; pulmäo esquerdo: 1,86 por cento/min) estäo de acordo com os dados encontrados na literatura