Technical Note: Experimental results from a prototype high-field inline MRI-linac

PURPOSE

The pursuit of real-time image guided radiotherapy using optimal tissue contrast has seen the development of several hybrid magnetic resonance imaging (MRI)-treatment systems, high field and low field, and inline and perpendicular configurations. As part of a new MRI-linac program, an MRI scanner was integrated with a linear accelerator to enable investigations of a coupled inline MRI-linac system. This work describes results from a prototype experimental system to demonstrate the feasibility of a high field inline MR-linac.

METHODS

The magnet is a 1.5 T MRI system (Sonata, Siemens Healthcare) was located in a purpose built radiofrequency (RF) cage enabling shielding from and close proximity to a linear accelerator with inline (and future perpendicular) orientation. A portable linear accelerator (Linatron, Varian) was installed together with a multileaf collimator (Millennium, Varian) to provide dynamic field collimation and the whole assembly built onto a stainless-steel rail system. A series of MRI-linac experiments was performed to investigate (1) image quality with beam on measured using a macropodine (kangaroo) ex vivo phantom; (2) the noise as a function of beam state measured using a 6-channel surface coil array; and (3) electron contamination effects measured using Gafchromic film and an electronic portal imaging device (EPID).

RESULTS

(1) Image quality was unaffected by the radiation beam with the macropodine phantom image with the beam on being almost identical to the image with the beam off. (2) Noise measured with a surface RF coil produced a 25% elevation of background intensity when the radiation beam was on. (3) Film and EPID measurements demonstrated electron focusing occurring along the centerline of the magnet axis.

CONCLUSIONS

A proof-of-concept high-field MRI-linac has been built and experimentally characterized. This system has allowed us to establish the efficacy of a high field inline MRI-linac and study a number of the technical challenges and solutions.

Assessment of Risk Factors, Feasibility and Acceptability of VIA for Cervical Cancer Screening and Prevention

Aims – To assess feasibility of visual inspection with acetic acid and treatment with cryotherapy for cervical cancer screening and prevention and assess risk factors for cervical cancer in the screened population.Methods – A prospective analysis of all patients enrolled for cervical cancer screening by visual inspection, meeting the eligibility criteria for screening and treatment as per national guidelines 2011 was analyzed form March 2012 to April 2013.Results – A total of 4138 met the eligibility criteria and were counseled for screening, 33 rejected for screening. Out of 4105 screened 241 were visual inspection with acetic acid positive, 211 were treated with cryotherapy, 25 treated with LEEP, 5 rejected to  treatment.  Mean age of patient in year’s ± SD 41.48 ± 9.72. The visual inspection with acetic acidpositivity rate was 5.9 %Conclusion – Single visit approach is a feasible and acceptable form of cervical cancer screening strategy in our population.

Arginyltransferase suppresses cell tumorigenic potential and inversely correlates with metastases in human cancers

Arginylation is an emerging post-translational modification mediated by arginyltransferase (ATE1) that is essential for mammalian embryogenesis and regulation of the cytoskeleton. Here, we discovered that Ate1-knockout (KO) embryonic fibroblasts exhibit tumorigenic properties, including abnormally rapid contact-independent growth, reduced ability to form cell-cell contacts and chromosomal aberrations. Ate1-KO fibroblasts can form large colonies in Matrigel and exhibit invasive behavior, unlike wild-type fibroblasts. Furthermore, Ate1-KO cells form tumors in subcutaneous xenograft assays in immunocompromised mice. Abnormal growth in these cells can be partially rescued by reintroduction of stably expressed specific Ate1 isoforms, which also reduce the ability of these cells to form tumors. Tumor array studies and bioinformatics analysis show that Ate1 is downregulated in several types of human cancer samples at the protein level, and that its transcription level inversely correlates with metastatic progression and patient survival. We conclude that Ate1-KO results in carcinogenic transformation of cultured fibroblasts, suggesting that in addition to its previously known activities Ate1 gene is essential for tumor suppression and also likely participates in suppression of metastatic growth.

Quantitative evaluation of diffusion-weighted imaging techniques for the purposes of radiotherapy planning in the prostate

OBJECTIVE

Diffusion-weighted imaging (DWI) is an important technique for the localization of prostate cancer, and its response assessment during treatment with radiotherapy (RT). However, it has known limitations in terms of distortions and artefacts using standard acquisition techniques. This study evaluates two alternative methods that offer the promise of improved image quality and the potential for more reliable and consistent diffusion data.

METHODS

Three DWI techniques were investigated; single-shot echoplanar imaging (EPI), EPI combined with reduced volume excitation (ZOOMit; Siemens Healthcare, Erlangen, Germany) and read-out segmentation with navigator-echo correction (RESOLVE; Siemens Healthcare). Daily measurements of apparent diffusion coefficient (ADC) value were made in a quality assurance phantom to assess the repeatability of each sequence. In order to evaluate the geometric integrity of these sequences, ten normal volunteers were scanned, and the prostate was contoured to compare its similarity with T2 weighted images.

RESULTS

Phantom ADC values were significantly higher using the standard EPI sequence than those of the other two sequences. Differences were also observed between sequences in terms of repeatability, with RESOLVE and EPI performing better than ZOOMit. Overall, the RESOLVE sequence provided the best agreement for the in vivo data with smaller differences in volume and higher contour similarity than T2 weighted imaging.

CONCLUSION

Important differences have been observed between each of the three techniques investigated with RESOLVE performing the best overall. We have adopted this sequence for routine RT simulation of prostate patients at Liverpool Cancer Therapy Centre.

ADVANCES IN KNOWLEDGE

This work will be of interest to the increasing number of centres wanting to incorporate quantitative DWI in a clinical setting.

Forest biomass flow for fuel wood, fodder and timber security among tribal communities of Jharkhand

The study investigated extraction and consumption pattern of fuel wood, fodder and timber and forest biomass flow for fuel wood, fodder and timber security among tribal communities in Bundu block of Ranchi district in Jharkhand (India). The study is based on personal interviews of the selected respondents through structured interview schedule, personal observations and participatory rural appraisal tools i.e. key informant interviews and focus group discussions carried out in the sample villages, using multi-stage random sampling technique. The study revealed that the total extraction of fuel wood from different sources in villages was 2978.40 tons annum(-1), at the rate of 0.68 tons per capita annum(-1), which was mostly consumed in cooking followed by cottage industries, heating, community functions and others. The average fodder requirement per household was around 47.77 kg day(-1) with a total requirement of 14227.34 tons annum(-1). The average timber requirement per household was computed to be 0.346 m3 annum(-1) accounting for a total timber demand of 282.49 m3 annum(-1), which is mostly utilized in housing, followed by agricultural implements, rural furniture, carts and carriages, fencing, cattle shed/ store house and others. Forest biomass is the major source of fuel wood, fodder and timber for the primitive societies of the area contributing 1533.28 tons annum(-1) (51.48%) of the total fuel wood requirement, 6971.55 tons annum(-1) (49.00%) of the total fodder requirement and 136.36 m3 annum(-1) (48.27%) of the total timber requirement. The forest biomass is exposed to enormous pressure for securing the needs by the aboriginal people, posing great threat to biodiversity and environment of the region. Therefore, forest biomass conservation through intervention of alternative avenues is imperative to keep pace with the current development and future challenges in the area.

Eotaxin-1 is involved in parasite clearance during chronic filarial infection

Eosinophil migration as key feature of helminth infection is increased during infection with filarial nematodes. In a mouse model of filariasis, we investigated the role of the eosinophil-attracting chemokine Eotaxin-1 on disease outcome. BALB/c and Eotaxin-1(-/-) mice were infected with the rodent filaria Litomosoides sigmodontis, and parasitic parameters, cellular migration to the site of infection, and cellular responsiveness were investigated. We found increased parasite survival but unaffected eosinophil migration to the site of infection in Eotaxin-1(-/-) mice. Expression of CD80 and CD86 was reduced on eosinophils from Eotaxin-1(-/-) mice after in vitro TLR2 stimulation and exposure to filarial antigen, respectively, suggesting a potential reduced activation state of eosinophils in Eotaxin-1 deficient mice. We further demonstrated that macrophages from Eotaxin-1(-/-) mice produce decreased amounts of IL-6 in vitro, a cytokine found to be associated with parasite containment, suggesting possible mechanisms by which Eotaxin-1 regulates activation of inflammatory cells and thus parasite survival.

Induction of Labor Using Misoprostol With or Without Mifepristone in Intrauterine Death

INTRODUCTION

Rapid expulsion of fetus in intrauterine fetal death is usually requested without any medical grounds for it. So an efficient, safe method for induction of labor is required. The objective of this study is to determine if pre-treatment with mifepristone followed by induction of labor with misoprostol in late intrauterine fetal death is more efficacious.

METHODS

We conducted a randomized controlled trial in 100 patients in B.P.Koirala Institute of Health Sciences, Nepal from June 2011 to May 2013. Group A women received single oral dose of 200 mg mifepristone, followed by induction with vaginal misoprostol after 24 hours. Group B women were induced only with vaginal misoprostol. In each group, five doses of misoprostol was used four hourly. If first cycle was unsuccessful, after break of 12 hour, second course of misoprostol was started. The primary outcome was a measure of induction to delivery time and vaginal delivery within 24 hours. Secondary outcome was to measure need of oxytocin and complications.

RESULTS

Maternal age, parity and period of gestation were comparable between groups. Number of misoprostol dose needed in group A was significantly less than group B. Mann Whitney U test showed, women in group A had significantly earlier onset of labor, however total induction to delivery interval was not significant. In group A, 85.7% delivered within 24 hours of first dose of misoprostol while in group B 70% delivered within 24 hours (p=0.07). More women in Group B required oxytocin.

CONCLUSIONS

Pretreatment with mifepristone before induction of labor following late intrauterine fetal death is an effective and safe regimen. It appears to shorten the duration of induction to onset of labor.

Subcutaneous Sterile Water Injection for Labor Pain: A Randomized Controlled Trial

Aims: This study was done to evaluate the effectiveness of subcutaneous injection of sterile water compared with placebo in reduction of labor pain. Methods: Two hundred and forty pregnant women at term planned for normal vaginal delivery during the first stage of labor were randomized to receive either subcutaneous injection of sterile water (study group, n=120) or normal saline as placebo (control group, n=120) at painful point in lumbosacral region. Pain score was measured before and 10, 45 and 90 minutes after the injections. Main outcome measured was reduction of low back labor pain using visual analogue scale. Results: The mean pain score was equal in both groups prior to the injection. The pain scores were significantly lower among the intervention group compared to the control group at 10, 45, 90 minutes after injection. There was no difference between the two groups with regard to rate of instrumental delivery, cesarean rate and neonatal outcome.Conclusions: The subcutaneous injection of sterile water administered at painful point in lumbosacral area was effective in reducing low back labor pain during labor. DOI: http://dx.doi.org/10.3126/njog.v8i2.9777

Assessment of Pelvic Organ Prolapse by Pelvic Organ Prolapse Quantification Technique Among Pre-operative Patients

Aims: This was performed to examine pelvic organ prolapse using POP-Q technique and correlate pre-existing urinary symptoms with segments of pelvic organ prolapse. Methods: All patients admitted with pelvic organ prolapse were included. Patients were asked regarding any concomitant urinary symptoms and then all patients were examined by POP-Q technique and correlation of urinary symptoms was done with various segments of pelvic organ prolapse. Results: Eighty patients were studied in one year duration. Majority of patients had presented with stage 4 prolapse (58.8%). Majority of patients had urinary symptoms among which 87.5% had increased urinary frequency, 88.8% had dysuria, 65% had stress urinary incontinence (SUI), 72.5% had incomplete evacuation. Dysuria and SUI was found to have significant correlation with anterior segment prolapse (p<0.05%). Conclusions: Site specific measurements by POP-Q system showed anterior segment prolapse to be more and were significantly associated with various urinary symptoms.Nepal Journal of Obstetrics and Gynaecology / Vol 8 / No. 2 / Issue 16 / July-Dec, 2013 / 26-29 DOI: http://dx.doi.org/10.3126/njog.v8i2.9765  

A case of isolated cutaneous Rosai-Dorfman-Syndrome

Rosai-Dorfman Syndrome (RDD) is a rare, benign, self-limiting disorder which is characterized by the non-malignant proliferation of distinctive histiocytic cell within lymphatic system. RDD has been described as a dynamic entity in the spectrum of histiocytosis with non-Langerhans cell histiocytosis at one end and Langerhans cell histiocytosis at the other. The exact etiology of this disease is uncertain despite widespread search for infectious or immunological reasons. We present a case of purely cutaneous Rosai-Dorfman Syndrome presenting as abdominal wall swelling.

KEYWORDS

Rosai-Dorfman Disease, Lymphoma.