Sanjeev Chawla

Demonstration of scolex within calcified cysticercus cyst: its possible role in the pathogenesis of perilesional edema.

Summary:  Purpose: This study was performed to understand the relation between the scolex as demonstrated on gradient echo (GRE) imaging in a calcified cysticercus cyst and the development of perilesional edema that may be of value in understanding the pathogenesis of this entity.

Human and porcine Taenia solium infection in rural north India

72 members of a pig farming community and 50 slaughtered pigs in Uttar Pradesh, India, were examined between November 2000 and June 2001 for Taenia solium infection. 27 of the human subjects (38%) had intestinal taeniasis and 7 (9.7%) had reported seizures. All 3 of the latter who were examined had neurocysticercosis. 13 of the pigs (26%) had cysticercosis. Such high prevalences indicate the need for detailed assessment of the disease burden in this community.

MR imaging and in vivo proton spectroscopy of the brain in neonates with hypoxic ischemic encephalopathy

INTRODUCTION A number of studies have suggested the potential utility of in vivo proton MR spectroscopy for the evaluation of brain injury in the asphyxiated neonates. We present our initial experience with in vivo proton MR spectroscopy in neonates who were diagnosed as having hypoxic injury on clinical examination and the severity of the insult was graded using Sarnat staging. METHODS AND MATERIAL MR imaging and in vivo proton MR spectroscopy was performed in 16 neonates with hypoxic ischemic encephalopathy (HIE) to correlate the imaging and metabolite abnormality with clinical severity of the condition at the time of insult and with outcome at 2 months of age. The ratios of different metabolites were calculated as observed on MR spectroscopy from an 8 ml voxel that included thalami, basal ganglia and part of the ventricular system using spin echo technique with an echo time of 135 ms. RESULTS AND DISCUSSION The results of the spectroscopy were compared with imaging abnormalities and Sarnats clinical staging of HIE. MR Imaging abnormalities included basal ganglia, thalamic and periventricular hemorrhage and periventricular hyperintensities and were noticed in 8/16 neonates with different stages of HIE. Maximum imaging abnormalities were noted in stage II (6/9) followed by stage III (1/2) and stage I (1/5), respectively. The alpha-Glx resonance at 3.76 ppm was seen in 14/16, Glycine at 3.56 ppm (Gly) was seen in 10/16 and Lactate (L) at 1.33 ppm was observed in 4/16 neonates with HIE. CONCLUSION MR spectroscopy was more sensitive than imaging in detecting the insult due to HIE and increased concentration of alpha-Glx/Cr and Gly/Cr correlated better with severity of the HIE. The demonstration of L was associated with poor outcome.

Comparative evaluation of magnetization transfer MR imaging and in-vivo proton MR spectroscopy in brain tuberculomas

We have compared and analyzed the value of in vivo proton MR spectroscopy (PMRS) and T1 weighted magnetization transfer (MT) MR imaging in tissue characterization of brain tuberculomas. We studied 33 cases of proven intracranial tuberculomas with in vivo PMRS and T1 weighted MT MR imaging. MT ratios from the rim and core of the tuberculomas were calculated and compared with metabolites seen on PMRS. Final diagnosis of tuberculoma was based on histopathology (n = 26) and/or associated tuberculous meningitis (n = 7) in all the cases. Out of the 33 patients who underwent both PMRS and T1 weighted MT MR imaging, spectroscopy showed only lipids at 0.9 ppm, 1.3 ppm, 2.0 ppm, and 2.80 ppm in 26 cases while lipids at 0.9 ppm, 1.3 ppm, 2.0 ppm and 2.80 ppm along with choline at 3.22 ppm was seen in remaining 7 patients. MT ratios from the core or solid necrosis varied from 21-29% while from the rim or cellular region varied from 16-24%. MT ratios from all the 33 lesions were consistent with tuberculomas while PMRS showed choline along with lipids in 7 predominantly cellular lesions simulating a neoplasm. We conclude that T1 weighted MT MR imaging appears to be more consistent in the tissue characterization of brain tuberculomas.

Correlative MR imaging and histopathology in porcine neurocysticercosis

To examine whether all the histopathologically seen features of cysticercus cysts excised from brain of swine naturally infected with neurocysticercosis during its evolution are actually visible on magnetic resonance imaging (MRI).

Magnetization transfer and T2 quantitation in normal appearing cortical gray matter and white matter adjacent to focal abnormality in patients with traumatic brain injury

Traumatic brain injury (TBI) is one of the commonest causes of morbidity and mortality in the developed countries with posttraumatic epilepsy and functional disability being its major sequelae. The purpose of this study was to test the hypothesis whether the normal appearing adjacent gray and white matter regions on T2 and T1 weighted magnetization transfer (MT) weighted images show any abnormality on quantitative imaging in patients with TBI. A total of 51 patients with TBI and 10 normal subjects were included in this study. There were significant differences in T2 and MT ratio values of T2 weighted and T1 weighted MT normal appearing gray matter regions adjacent to focal image abnormality compared to normal gray matter regions in the normal individuals as corresponding contralateral regions of the TBI patients group (p < 0.05). However the adjoining normal appearing white matter quantitative values did not show any significant change compared to the corresponding contralateral normal white matter values. We conclude that quantitative T2 and MT ratio values provide additional abnormality in patients with TBI that is not discernable on conventional T2 weighted and T1 weighted MT imaging especially in gray matter. This additional information may be of value in overall management of these patients with TBI.

Multiparametric quantitation of the perilesional region in patients with healed or healing solitary cysticercus granuloma.

The purpose of this study was to compute T2 values and magnetization transfer (MT) ratios in the perilesional region of healing and healed cysticercus granulomas to determine if there are T2 abnormalities not apparent on conventional T2-weighted imaging and to determine the relationship between seizure control and the quantitative measures. Sixty-three patients were studied. T2 values and MT ratios were computed for the perilesional region and were compared with measurements from the contralateral normal-appearing region. A significantly increased T2 value was found for the perilesional region compared to the corresponding contralateral region despite the absence of qualitative abnormality on conventional T2-weighted magnetic resonance imaging. For patients showing normal-appearing perilesional regions on MT imaging, there was no significant difference in T2 and MT ratios between the perilesional and the normal contralateral regions. There was a statistically significant inverse correlation between perilesional T2 values and MT ratios, suggesting each was associated with perilesional gliosis. The study illustrates that quantitative evaluation of MT ratios and T2 augments the qualitative visual assessment of the perilesional region in healing or healed cysticercus granulomas.

Higher succinate than acetate levels differentiate cerebral degenerating cysticerci from anaerobic abscesses on in-vivo proton MR spectroscopy

We present three patients with large intraparenchymal isolated degenerating cysticerci in whom the diagnosis was primarily based on in-vivo proton MR spectroscopy, and subsequently confirmed histologically. We suggest that the presence of succinate alone or more succinate acetate indicates the presence of degenerating cysticerci and differentiates them from anaerobic brain abscesses, which show acetate alone or in higher concentration than succinate, even when the clinical and imaging features are similar.

Broad identification of bacterial type from pus by 1H MR spectroscopy.

Background  Abscess formation is a common bacterial infection and requires an immediate antimicrobial approach for apposite treatment. Delay in patient treatment is usually a common feature, as the bacterial identification of clinical samples is based on the culture, which is a time‐consuming exercise. The current study was aimed at developing an alternative technique with the potential for rapid bacterial group identification.

Marker of parasitic cysts on in vivo proton magnetic resonance spectroscopy: is it succinate or pyruvate?

We read with interest the article entitled “Pyruvate: An In Vivo Marker of Cestodal Infection of Human Brain on Proton MR Spectroscopy” published in the December 2003 issue of the Journal of Magnetic Resonance Imaging (1). The authors reported that pyruvate, and not succinate, is the marker of identification and viability of parasitic cysts on in vivo proton magnetic resonance spectroscopy (1H MRS). We disagree with these observations and conclusions and are of the opinion that succinate, not pyruvate, should be considered as a marker for cestodal infections. Over the last several years, we have been working on the characterization of intracranial cystic lesions of different pathologies, including parasitic cysts using in vivo and ex vivo 1H MRS (2,3,5,8– 15). Earlier, we documented a case of an intracranial hydatid cyst in which, besides other signals, we observed a large resonance at 2.41 ppm on in vivo 1H MRS (3). We confirmed these findings by performing ex vivo high-resolution 1H MRS of the fluid aspirated from same cyst as well as fluid from a cyst in the liver of the same patient. We assigned aforesaid resonance as pyruvate, which was further confirmed on spiking by adding pyruvate to the fluid samples. In thesameyear,Rémyetal (4) performed invivoand invitro 1H MRS experiments in patients of brain abscesses and assigned the resonance at 2.4 ppm as succinate. In our subsequent study, we also observed a resonance at 2.4 ppm in seven patients with pyogenic brain abscess, however, we still considered this peak as pyruvate (5). At that time, to characterize the resonance at 2.4 ppm, Kreis et al (6) added pyruvate and succinate to one Echinococcus granulomas cyst sample and performed double inverse heteronuclear 1H/13C correlation spectroscopy (COSY) experiment with and without 1H decoupling in the 1 dimension. Decoupled COSY spectrum showed 13C chemical shift of 34 ppm for succinate. In a 1 undecoupled COSY spectrum, the peak split up along 1 into a doublet with a splitting of 2J (6). Subsequently, Willker et al (7) also established a singlet at 2.40 ppm as succinate by heteronuclear single quantum correlation spectroscopy (HSQC) experiment as the chemical shift for the13CH2 moietyof succinateappearedat35.01 ppm in the 1 dimension. At this stage, we realized our mistake of incorrectly marking the peak at 2.4 ppm as pyruvate and started assigning this resonance as succinate in our subsequent studies (8–15). We also carried out HSQC experiments of the fluid samples from cysticercus and hydatid cysts obtained from different locations of animals and humans to confirm the resonance of succinate at 2.4 ppm (12). Jayakumar et al (1) also mentioned that pyruvate may be regarded as the marker for viability of parasitic etiology. This conclusion is contrary to our results. We have been consistently observing succinate in all the samples of hydatid and cysticercus fluid regardless of the evolutionary stage of the cyst. Recently, we have shown fumarate (6.54 ppm) and malate (4.3 ppm) as characteristic markers for the viability of hydatid cysts (13) and creatine (3.03 ppm) of cysticercus cysts (14) by correlating the metabolite pattern as observed on high resolution ex vivo 1H MRS experiments with histopathology. Moreover, we have also observed a resonance at 2.4 ppm from degenerating neurocysticercosis in addition to viable cysticercus cysts on in vivo 1H MRS in large number of patients (15). In conclusion, we feel that the resonance at 2.4 ppm in question should be assigned to succinate and is not a predictor of the viability of these parasitic cysts.