Can diffusion tensor metrics help in preoperative grading of diffusely infiltrating astrocytomas? A retrospective study of 36 cases.

INTRODUCTION: Diffusion weighted imaging and diffusion tensor imaging (DTI) give information about the amount and directionality of water diffusion occurring in a given tissue. Here we study the role of diffusion tensor metrics including fractional anisotropy (FA) and spherical anisotropy (CS) in preoperative grading of diffusely infiltrating astrocytomas. METHODS: We performed DTI in 38 patients with pathologically proven diffusely infiltrating astrocytomas, who were classified into two groups, i.e., 15 patients with high-grade astrocytoma (HGAs, WHO grade III and IV) and 23 patients with low-grade astrocytoma (LGAs, WHO grade II). We measured maximum FA and minimum CS values in all cases from tumor. Histopathological diagnosis was established in all cases. RESULTS: The mean maximum FA values were higher in HGA (0.583 ± 0.104) than LGA (0.295 ± 0.058), while mean minimum CS values were lower in HGA (0.42 ± 0.121) than LGA (0.722 ± 0.061). The difference in the diffusion tensor indices between HGA and LGA was found to be statistically significant with P value of <0.001. Keeping cutoff FA value of 0.4, all HGAs showed higher maximum FA values, and all LGAs showed lower maximum FA values. Also, all HGAs showed minimum CS values less than a cutoff value of 0.6, and all LGAs showed minimum CS values higher than 0.6. CONCLUSION: Diffusion tensor metrics such as maximum FA and minimum CS can help to differentiate HGA from LGA.

The efficacy of transforaminal epidural steroid injections in lumbosacral radiculopathy.

BACKGROUND: Transformational epidural steroid (TFES) is commonly used to treat lumbosacral radicular pain. However, very few studies have systematically evaluated the quality of analgesia following such procedures with respect to time. OBJECTIVE: To evaluate long-term efficacy of TFES in patients with lumbosacral radiculopathy. MATERIALS AND METHODS: A prospective study including 30 patients having lumbosacral radiculopathy secondary to prolapsed disc. Outcome variables were the amount of improvement just after the procedure and thereafter at 24 hrs, 1 month, 6 month and 1 year post-procedure, respectively, using visual analog scale (VAS) and numeric rating scale (NRS). Patients also filled Roland-Morris questionnaire pre-procedure, 6 month and 1 year follow-up. All patients received Ibuprofen for 3 days following the procedure, to alleviate post- procedural pain. An option of rescue surgery was reserved in case of unbearable pain (>7 VAS), appearance of sudden motor deficit or if patient opts for surgery. Same injection was repeated if at any point of time pain had >5 in VAS. RESULTS: As per NRS, almost all patients had complete pain relief (mean 98%) immediate postprocedure. At 24 hrs, the score was 79%, at 1 month 60%, at 6 months 58.5% and at 1 year 59%. Preprocedure VAS was 9.2 and thereafter 0.6, 1.8, 3.9, 3.8 and 4.2 at similar time points. Roland-Morris score was 18/24, 10/24, 9/24, at pre-procedure, at 6 months and at 1 year, respectively. No complication was noted in any patient except post procedural local pain. CONCLUSION: Quality of pain relief produced by TFES was significant. Long-term quality of pain relief was better in patients with pain duration less than 6 months. Even though, the study was designed to inject the drug once, many of the patients required second injection. A further study with multiple injections at prefixed time interval might probably result in a better overall outcome.

Diffusion tensor mode in imaging of intracranial epidermoid cysts: one step ahead of fractional anisotropy.

INTRODUCTION: The signal characteristics of an epidermoid on T2-weighted imaging have been attributed to the presence of increased water content within the tumor. In this study, we explore the utility of diffusion tensor imaging (DTI) and diffusion tensor metrics (DTM) in knowing the microstructural anatomy of epidermoid cysts. MATERIALS AND METHODS: DTI was performed in ten patients with epidermoid cysts. Directionally averaged mean diffusivity (D(av)), exponential diffusion, and DTM-like fractional anisotropy (FA), diffusion tensor mode (mode), linear (CL), planar (CP), and spherical (CS) anisotropy were measured from the tumor as well as from the normal-looking white matter. RESULTS: Epidermoid cysts showed high FA. However, D(av) and exponential diffusion values did not show any restriction of diffusion. Diffusion tensor mode values were near -1, and CP values were high within the tumor. This suggested preferential diffusion of water molecules along a two-dimensional geometry (plane) in epidermoid cysts, which could be attributed to the parallel-layered arrangement of keratin filaments and flakes within these tumors. CONCLUSION: Thus, advanced imaging modalities like DTI with DTM can provide information regarding the microstructural anatomy of the epidermoid cysts.