Recent trends in Molecular Imaging : PET/CT in Neurology.

PET/CT is an important molecular imaging technique for the assessment of neurological disorders. The most widely used radiopharmaceutical for both clinical and research purposes is [18F] 2-fluoro-2-deoxy-D-glucose (FDG). It is extensively used owing to its favourable physical characteristics. It enables depiction of cerebral glucose metabolism, and has thus been used to study various pathological states. Despite this, FDG has its own limitations. This is owing to its limited specificity and high cortical uptake. This has paved the way for the development of several non-FDG PET radiopharmaceuticals. We present the insights gained at our institution, using these radiotracers in the assessment of neurological disease. Our study shows that the use of FDG and non-FDG novel PET radiopharmaceuticals facilitates the early diagnosis, delineation of extent, prognostication and monitoring of therapeutic response in several neuropathological states.

Stem cell therapy: A novel & futuristic treatment modality for disaster injuries.

Stem cell therapy hold the potential to meet the demand for transplant cells/tissues needed for treating damages resulting from both natural and man-made disasters. Pluripotency makes embryonic stem cells and induced pluripotent stem cells ideal for use, but their teratogenic character is a major hindrance. Therapeutic benefits of bone marrow transplantation are well known but characterizing the potentialities of haematopoietic and mesenchymal cells is essential. Haematopoietic stem cells (HSCs) have been used for treating both haematopoietic and non-haematopoietic disorders. Ease of isolation, in vitro expansion, and hypoimmunogenecity have brought mesenchymal stem cells (MSCs) into limelight. Though differentiation of MSCs into tissue-specific cells has been reported, differentiation-independent mechanisms seem to play a more significant role in tissue repair which need to be addressed further. The safety and feasibility of MSCs have been demonstrated in clinical trials, and their use in combination with HSC for radiation injury treatment seems to have extended benefit. Therefore, using stem cells for treatment of disaster injuries along with the conventional medical practice would likely accelerate the repair process and improve the quality of life of the victim.

Etiological profile of stroke and its relation with prothrombotic states.

OBJECTIVE: To study the etiological profile of childhood stroke and its relation with prothrombotic states. METHODS: Children with acute stroke with no evidence of CNS infection or head injury were studied. Stroke was confirmed by CT scan and further evaluated by MRI. Cardiac status was assessed with transthoracic echocardiography. Test for hypercoagulable state (antithrombin III, protein C, protein S, anticardiolipin antibody IgG and IgM and lupus anticoagulant) were done in all patients. RESULTS: A total of 66 children were enrolled--36 cases and 30 controls. Presenting symptoms were motor deficit (72%), seizure (66%), altered sensorium (36%), aphasia (27%). Causes identified were antiphospholipid antibody syndrome (25%), Moya Moya disease (16.6%), cardiac disease (11.1%), vasculitis (5.5%), ATIII deficiency (5.5%), Protein C deficiency (2.7%). Etiology remained unknown in 25% of cases with infarction. Hemorrhage was seen in 8.2% of cases and they had DIC or liver disease as the underlying cause. CONCLUSIONS: Magnetic Resonance Angiography and ELISA for antiphospholipid antibody should be done in all patients with stroke without an obvious cause.

Cortical activation during finger tapping in thyroid dysfunction: a functional magnetic resonance imaging study.

Thyroid dysfunction is associated with attention deficit and impairment of the motor system (muscle weakness and fatigue). This paper investigates possible motor function deficit in thyroid patients,compared to the controls. Functional MRI studies (fMRI)were carried out in five hypo and five hyperthyroid patients and six healthy volunteers. Whole brain imaging was performed using echo planar imaging (EPI)technique, on a 1.5T whole body MR system (Siemens Magnetom Vision). The task paradigm consisted of 8 cycles of active and reference phases of 6 measurements each, with right index finger tapping at a rate of 120 taps/min. Post-processing was performed using statistical parametric mapping on a voxel-by-voxel basis using SPM99. Clusters of activation were found in the contralateral hemisphere in primary somatomotor area (M1), supplementary motor area (SMA), somatosensory,auditory receptive and integration areas, inferior temporal lobe, thalamus and cerebellum. Increased clusters of activation were observed in M1 in thyroid subjects as compared to controls and with bilateral activation of the primary motor cortex in two hyperthyroid patients. The results are explained in terms of increased functional demands in thyroid patients compared to volunteers for the execution of the same task.

Acute disseminated encephalomyelitis--a case series.

Acute disseminated encephalomyelitis(ADEM) is an uncommon inflammatory demyelinating disease involving central nervous system white matter. A series of seven cases seen over a period of one year have been described. The patients presented with acute onset of focal neurological deficit (3 patients), alteration of sensorium(3) and ataxia(1). CT scan showed non specific hypodensity in 4 cases and was normal in 3 patients . MRI showed characteristic radiological changes. Complete recovery was seen in 3 patients , one died and 3 were left with sequelae.

Role of in vivo proton MR spectroscopy in the evaluation of adult brain lesions: our preliminary experience.

CONTEXT: A definite diagnosis and characterization of intracranial mass lesions, based on structural Magnetic Resonance Imaging (MRI) alone may be difficult. In such cases Proton Magnetic Resonance Spectroscopy (1H-MRS) along with other non-invasive techniques represents an advance in the specificity of brain lesion diagnosis. AIMS: The primary aim of this study was to evaluate the extent of the utility of 1H-MRS in adult brain tumors and their differentiation from similar-appearing space-occupying lesions. MATERIAL AND METHODS: MRS studies were performed on 1.5 Tesla whole body MR system using standard imaging head coil. Sixty patients (aged 30-65 years), including 35 males (31-65 years) and 25 females (30-65 years) were studied, along with 25 age-matched healthy volunteers (30-64 years). The Student 't' test was used to statistically analyze the spectroscopic data for significant difference in the metabolite ratios of the lesions from normal brain tissue. RESULTS: The Cho/Cr ratio was significantly raised in low and high-grade glioma and meningioma patients (1.85 +/- 0.36, 3.50 +/- 1.00 and 6.65 +/- 2.83 respectively) (mean +/- standard deviation), as compared with the control group (1.16 +/- 0.18); and NAA/Cr and NAA/Cho ratios were found to be lower than normal values in our study (P<0.01). However, in the non-neoplastic lesions, the Cho/Cr ratios were not statistically significant. The tubercular lesions revealed an average Cho/Cr ratio of 1.24 +/- 0.18, while it was 1.14 +/- 0.07 for infarcts. CONCLUSION: MR Spectroscopy was useful to arrive at a more definitive diagnosis in doubtful intracranial space-occupying lesions with similar morphological imaging patterns.

Atypical manifestation of dural arteriovenous fistula.

A case of secondary dural arteriovenous fistula presenting as infantile stroke, in a fifteen month old boy, is reported. The initial impression on CT scan in this case was misleading, due to the atypical appearance of the pathological periventricular blood vessels, interpreted as periventricular calcification.

Functional magnetic resonance imaging of the primary motor cortex in humans: response to increased functional demands.

Functional magnetic resonance imaging (fMRI) studies have been performed on 20 right handed volunteers at 1.5 Tesla using echo planar imaging (EPI) protocol. Index finger tapping invoked localized activation in the primary motor area. Consistent and highly reproducible activation in the primary motor area was observed in six different sessions of a volunteer over a period of one month. Increased tapping rate resulted in increase in the blood oxygenation level dependent (BOLD) signal intensity as well as the volume/area of activation (pixels) in the contralateral primary motor area up to tapping rate of 120 taps/min (2 Hz), beyond which it saturates. Activation in supplementary motor area was also observed. The obtained results are correlated to increased functional demands.

Co-existence of dual intracranial pathology clinical relevance of proton MRS.

The co-existence of neuro-cysticercosis (NCC) and intracranial neoplasm in an individual is a rare entity. Atypical presentation of cerebral cysticercosis may mimic glioma, metastasis, cerebral abscess or vice versa. The dual existence of these two lesions have led to several postulates which may have clinical impact in due course of time i.e. NCC as an oncogenetic factor for glioma or similarity of antigen found in glioma and NCC etc. An adequate management of such cases poses a challenge to both imageologists as well as clinicians. Thus, a proper diagnostic evaluation is essential for successful management of such cases. MR spectroscopy (MRS), although still a clinical research tool, may be extremely useful for exclusion or confirmation of neoplastic lesions in such a clinical scenario. The findings of MRS in collaboration with imaging parameters may increase the diagnostic yield of a MR investigation. The authors encountered five cases of dual intracranial pathologies i.e. neurocysticercosis and glioma. MR spectroscopy was useful to arrive at a definitive diagnosis in such a situation.

Role of guided fine needle aspiration cytology in diagnosis and classification of liver malignancies.

Ultrasound or CT-guided fine needle aspiration was performed on 212 patients with space occupying lesions of the liver during a period of 5 years (1986-1990) to study the utility of fine needle aspiration (FNAC) in the diagnosis of hepatic malignancies. The initial FNAC diagnosis was malignancy in 91 cases. However, following review of the smears by one of the investigators (DKD) 93 (43.9%) cases were found to be malignant. Age of the patients with malignancy ranged from 20 days to 85 years. Male to female ratio was 57:36. The clinical diagnosis was malignancy in 58% which improved to 72% following imaging whereas nonspecific diagnosis was reduced from 34% to 20%. The primary malignancies consisted of 21 cases of hepatocellular carcinoma (HCC) and 7 hepatoblastomas. There were 61 metastatic lesions which included 43 adenocarcinomas, 6 small cell anaplastic carcinomas, 3 leiomyosarcomas, 2 cases each of malignant melanoma, paraganglioma and germ cell tumour, and one case each of squamous cell carcinoma, neuroendocrine tumour and undifferentiated carcinoma/soft tissue sarcoma. In two cases decision between HCC and secondaries was not possible. There were also two cases of non-Hodgkin's lymphoma. Thirty six percent of primary malignancies and 58% of secondaries were correctly diagnosed or suggested as one of the possibilities by combined clinical examination and imaging prior to FNAC. Thus, US/ CT guided FNAC played an important role in diagnosis and classification of malignancies of liver.

Ultrasound guided percutaneous fine needle aspiration cytology of pancreas: a review of 61 cases.

The study includes 61 cases which were subjected to ultrasound (US) guided fine needle aspiration cytology (FNAC) to find out the utility of this technique in the diagnosis of pancreatic lesions. Age of the patients ranged from 23 to 85 years with a median of 50 years. Male to female ratio was 36:25. One or more clinical diagnoses were offered in 16 and in 9 of these, the disease was related to pancreas. Subsequent to US, the lesions were localized to pancreas in 57 and the nature of pathology in the pancreatic lesion could be diagnosed in 31. By FNAC, 31 cases (50.8%) were diagnosed to have pancreatic malignancy which included adenocarcinoma (23 cases), papillary cystic tumour (1), muco-epidermoid carcinoma (1), acinic cell carcinoma (1), islet cell tumor (1), and non Hodgkin lymphoma (4). FNAC of liver in 2 cases and retroperitoneal lymph node in a case of pancreatic adenocarcinoma revealed metastasis. During follow up, 1 case of non Hodgkin's lymphoma showed CSF involvement. Three cases (4.9%) were suspected to have epithelial malignancy of which one was confirmed as an adenocarcinoma following surgery and histology. Four (6.6%) were benign lesions which included nonspecific inflammation (2 cases), tuberculous pancreatitis (1) and pseudopancreatic cyst (1). The remaining 23 cases (37.7%) had normal or inadequate cytology. Of these, FNAC of liver showed metastasis in 2 cases and one case each were diagnosed as adenocarcinoma and pseudopancreatic cyst respectively following surgery. None of the patients had any complication following FNAC. We recommend US guided FNAC to be routinely used for diagnosis of pancreatic lesion.

MRI (magnetic resonance imaging) spectrum of epilepsy.

In 361 patients with strong clinical suspicion of secondary epilepsy magnetic resonance imaging (MRI) was performed. Three hundred and forty-five patients revealed a positive study. Maximum number of patients (28.3%) were in the age group of 2 to 12 years without any significant sex predilection. More than 70% patients presented with generalised seizures. MRI revealed definite evidence of tuberculoma in 98, neurocysticercosis in 86, tumour in 60 and cerebrovascular accident in 23 patients. There were 78 patients in miscellaneous group which included patients with magnetic resonance (MR) diagnosis of generalised or focal atrophy, demyelinating disease, hydrocephalus with or without basal exudates, calcification and disappearing lesion. In 16 patients MR was found to be within normal limits.

Adenosine deaminase activity in pleural fluid--a diagnostic test of tuberculous pleural effusion.

Adenosine deaminase (ADA) activity in pleural fluids was studied in 47 patients with pleural effusion of different etiology. Patients were divided into two groups: Group I - Tuberculous pleural effusion (21 patients): Group II - Non tuberculous effusion (26 patients) and these included malignant pleural effusion (9 cases), synpneumonic pleural effusion (9 cases) and transudative pleural effusion (8 cases). The mean ADA activity was 64.67 IU/L +/- 21.68 in group I and 6.99 +/- 3.69 in Group II. Increased mean pleural fluid ADA activity in tuberculous pleural effusion was highly significant (p < 0.001) when compared with pleural effusion of non-tuberculous etiology. Based on lowest value of ADA activity found in tuberculous pleural effusion (30 IU/L), the test has a sensitivity and specificity of 1.

Undescended testis: evaluation by magnetic resonance imaging.

We describe our experience of prospective magnetic resonance imaging (MRI) study in patients of undescended testis, with a 1.5 T equipment using body coil. There were thirty two patients, aged 1.5 to 14 years with a mean age of nine years. Surgical follow up was obtained for thirty one patients. We were able to indicate the position of 26 testes in 22 patients and absence of five testes in three patients. MRI was falsely positive and negative for five and two testes, respectively. Testicular tissue at ectopic site was identified by presence of characteristic signal intensity pattern, mediastinum testis and its location along empty spermatic canal in cases of inguinal testis either singly or in combination. MRI was able to detect atrophic changes in four testes, confirmed on surgery. The study concludes that MR imaging is useful in the localization and tissue characterization of a non palpable testis. However, it is not sensitive enough for complete exclusion of the diagnosis of an undescended testis. Thus a surgical or laproscopic exploration may be needed further in selective cases for the management of patient.

Magnetic resonance imaging in childhood epilepsy.

One hundred and seventy children of chronic seizures with strong clinical suspicion of an underlying intracranial lesion as its cause were studied by Magnetic Resonance Imaging (MRI). Maximum number of patients were between 6-12 years, males outnumbering females. Structural abnormalities were seen in 158 of the 170 patients. The study revealed tuberculoma as the commonest lesion in this series (n = 64) followed by cysticercosis (n = 27). Three patients were seen to have glioma. An interesting finding was disappearing lesion in 6 children. MRI proved to be an excellent modality in demonstrating and characterising the intracranial lesion.