White Matter Changes Related to Subconcussive Impact Frequency during a Single Season of High School Football.

BACKGROUND AND PURPOSE: The effect of exposing the developing brain of a high school football player to subconcussive impacts during a single season is unknown. The purpose of this pilot study was to use diffusion tensor imaging to assess white matter changes during a single high school football season, and to correlate these changes with impacts measured by helmet accelerometer data and neurocognitive test scores collected during the same period. MATERIALS AND METHODS: Seventeen male athletes (mean age, 16 ± 0.73 years) underwent MR imaging before and after the season. Changes in fractional anisotropy across the white matter skeleton were assessed with Tract-Based Spatial Statistics and ROI analysis. RESULTS: The mean number of impacts over a 10-g threshold sustained was 414 ± 291. Voxelwise analysis failed to show significant changes in fractional anisotropy across the season or a correlation with impact frequency, after correcting for multiple comparisons. ROI analysis showed significant (P < .05, corrected) decreases in fractional anisotropy in the fornix-stria terminalis and cingulum hippocampus, which were related to impact frequency. The effects were strongest in the fornix-stria terminalis, where decreases in fractional anisotropy correlated with worsening visual memory. CONCLUSIONS: Our findings suggest that subclinical neurotrauma related to participation in American football may result in white matter injury and that alterations in white matter tracts within the limbic system may be detectable after only 1 season of play at the high school level.

Effect of probiotic Pediococcus acidilactici FT28 on growth performance, nutrient digestibility, health status, meat quality, and intestinal morphology in growing pigs.

AIM: The experiment was conducted to evaluate the effect of swine-origin probiotic Pediococcus acidilactici FT28 on growth, nutrient utilization, health status, meat quality and intestinal morphology in growing female pigs. MATERIALS AND METHODS: Pigs (n=27) were distributed into three groups (3 replicates of 3 each) and supplemented with basal diet either without probiotics (C) or with a probiotic of dairy-based (Lactobacillus acidophilus NCDC-15; TLact) or swine based (P. acidilactici FT28; TPedic). The probiotics were fed as fermented feed at 200 g/pig/day. At the end of the trial, six pigs from each group were selected for metabolism trial and then sacrificed to determine meat quality and intestinal morphology. RESULTS: Supplementation of both probiotics improved growth performance, whereas feed intake, digestibility of CP and N retention were better (p<0.05) in P. acidilactici FT28-fed group. However , the digestibility of dry matter (DM), organic matter (OM), ether extracts (EE), crude fiber and nitrogen free extract did not show any significant effect on probiotic supplementation. The serum A: G ratio, triglyceride, and cholesterol level were also improved (p<0.05) in TPedic group compared to other treatment groups. Both probiotic supplementations showed lower (p<0.05) serum glucose level with similar protein and albumin value, which indicated good utilization of feed as well as health status of growing pigs. Dressing percentage, vital organ weight, and EE of loin meat were higher (p<0.05) in probiotic-supplemented groups compared to control. However, P. acidilactici FT28-fed animals showed higher (p<0.05) CP and total ash percentage of meat without affecting pH, water holding capacity, and extract release volume of loin muscle. The villi height and crypt depth were better in both supplemented groups compared to control. CONCLUSION: Results of the present study revealed that P. acidilactici FT28 could serve as better probiotic source in swine production for the better utilization of CP and N-retention in meat with improved health status and intestinal morphology.

Clinical profile of nonsmall cell lung carcinoma patients treated in a single unit at a tertiary cancer care center.

BACKGROUND: Recent advances and understanding in the field of lung cancer and advent of newer treatments have shown a significant improvement in survival in the patients. The present study was conducted to analyze the clinical profile of nonsmall cell lung cancer (NSCLC) patients treated in a single unit at a tertiary cancer care center. MATERIALS AND METHODS: In this retrospective analysis, 322 consecutive NSCLC patients from the year 2011 to 2012 treated in a single unit were included in the study. Patients with proven NSCLC were included in the study. The details of the patients included the demographic profile, pathological diagnosis as well as imaging data, tumor profile, details of treatment, and follow-up information. RESULTS: The majority of the patients (95.6%) were in the age group >40 years. A large group of the patients (57.1%) were present/reformed smokers. The major histological type was adenocarcinoma (60.9%), of which 22.8% patients were found to be epidermal growth factor receptor positive. Anaplastic lymphoma kinase rearrangement positivity rate was 4.8%. Furthermore, 68% patients had Stage 4 disease. Upfront palliative chemotherapy (CT) was offered in 61.8% patients and pemetrexed with platinum compounds was the main CT regimen (46.6%). Partial response was achieved in 45.7% patients, whereas stable disease was observed in 10.9% cases. Median progression-free survival was 5 months and overall survival was 55% at 36 months. CONCLUSION: NSCLC forms the largest subgroup of lung cancer with the patients presenting with advanced stages of disease. This area needs to be explored for the early detection and subsequently the radical treatment of the patients. Personalized approach may be considered for the management of lung cancer by identifying new predictive and prognostic biomarkers of this disease.

Association between neoadjuvant chemoradiation and survival for patients with locally advanced rectal cancer.

AIM: To examine the overall survival differences for the following neoadjuvant therapy modalities - no therapy, chemotherapy alone, radiation alone and chemoradiation - in a large cohort of patients with locally advanced rectal cancer. METHOD: Adults with clinical Stage II and III rectal adenocarcinoma were selected from the National Cancer Database and grouped by type of neoadjuvant therapy received: no therapy, chemotherapy only, radiotherapy only or chemoradiation. Multivariable regression methods were used to compare adjusted differences in perioperative outcomes and overall survival. RESULTS: Among 32 978 patients included, 9714 (29.5%) received no neoadjuvant therapy, 890 (2.7%) chemotherapy only, 1170 (3.5%) radiotherapy only and 21 204 (64.3%) chemoradiation. Compared with no therapy, chemotherapy or radiotherapy alone were not associated with any adjusted differences in surgical margin positivity, permanent colostomy rate or overall survival (all P > 0.05). With adjustment, neoadjuvant chemoradiation vs no therapy was associated with a lower likelihood of surgical margin positivity (OR 0.74, P < 0.001), decreased rate of permanent colostomy (OR 0.77, P < 0.001) and overall survival [hazard ratio (HR) 0.79, P < 0.001]. When compared with chemotherapy or radiotherapy alone, chemoradiation remained associated with improved overall survival (vs chemotherapy alone HR 0.83, P = 0.04; vs radiotherapy alone HR 0.83, P < 0.019). CONCLUSION: Neoadjuvant chemoradiation, not chemotherapy or radiotherapy alone, is important for sphincter preservation, R0 resection and survival for patients with locally advanced rectal cancer. Despite this finding, one-third of patients in the United States with locally advanced rectal cancer fail to receive stage-appropriate chemoradiation.

Inadvertent Intrafacet Injection during Lumbar Interlaminar Epidural Steroid Injection: A Comparison of CT Fluoroscopic and Conventional Fluoroscopic Guidance.

BACKGROUND AND PURPOSE: Inadvertent intrafacet injection can occur during interlaminar epidural steroid injection, resulting in a false-positive loss of resistance and nontarget injection of medication. The purpose of this investigation was to compare the observed rates of this phenomenon during lumbar interlaminar epidural steroid injection performed by using conventional fluoroscopic and CT fluoroscopic guidance. MATERIALS AND METHODS: We retrospectively reviewed 349 lumbar interlaminar epidural steroid injections performed by using conventional fluoroscopy or CT fluoroscopic guidance to determine the observed rates of inadvertent intrafacet injection with each technique. Cases of inadvertent intrafacet injection were classified as either recognized or unrecognized by the proceduralist at the time of the procedure. Multivariate logistic regression was used to determine the independent effect of imaging guidance technique, age, and sex. RESULTS: The rate of inadvertent intrafacet injection was observed to be 7.5% in the CT fluoroscopic group and 0.75% in the conventional fluoroscopy group. All 16 cases identified from CT fluoroscopic procedures were recognized during the procedure; the single case identified from conventional fluoroscopy procedures was not recognized prospectively. The type of imaging guidance showed a statistically significant effect on the detection of the phenomenon (OR for conventional fluoroscopy versus CT fluoroscopy = 0.10, P = .03) that was independent of differences in age or sex. CONCLUSIONS: Inadvertent intrafacet injection is identified during CT fluoroscopic-guided interlaminar epidural steroid injection at a rate that is 10-fold greater than the same procedure performed under conventional fluoroscopy guidance.

Imaging Signs in Spontaneous Intracranial Hypotension: Prevalence and Relationship to CSF Pressure.

BACKGROUND AND PURPOSE: Patients with spontaneous intracranial hypotension often exhibit low CSF pressure and changes on brain MR imaging and/or evidence of CSF leak on myelography. We investigated whether individual imaging signs of spontaneous intracranial hypotension correlate with measured CSF pressure and how frequently these 2 markers of spontaneous intracranial hypotension were concordant. MATERIALS AND METHODS: We performed a retrospective, cross-sectional study of 99 subjects with spontaneous intracranial hypotension. Prevalence of brain and myelographic imaging signs of spontaneous intracranial hypotension was recorded. CSF pressure among subjects with or without individual imaging signs was compared by using a 2-tailed t test and ANOVA. Concordance between low CSF pressure (≤6 cm H2O) and imaging was defined as the presence of the sign in a subject with low CSF pressure or absence of the sign when pressure was not low. RESULTS: Dural enhancement, brain sagging, and venous distension sign were present in 83%, 61%, and 75% of subjects, respectively, and myelographic evidence of CSF leak was seen in 55%. Marginal correlations between CSF pressure and brain sagging (P = .046) and the venous distension sign (P = .047) were found. Dural enhancement and myelographic evidence of leak were not significantly correlated with CSF pressure. Rates of concordance between imaging signs and low CSF pressure were generally low, ranging from 39% to 55%. CONCLUSIONS: Brain and myelographic signs of spontaneous intracranial hypotension correlate poorly with CSF pressure. These findings reinforce the need to base the diagnosis of spontaneous intracranial hypotension on multiple diagnostic criteria and suggest the presence of patient-specific variables that influence CSF pressure in these individuals.

Radiology reports for incidental thyroid nodules on CT and MRI: high variability across subspecialties.

BACKGROUND AND PURPOSE: Variability in radiologists' reporting styles and recommendations for incidental thyroid nodules can lead to confusion among clinicians and may contribute to inconsistent patient care. Our aim was to describe reporting practices of radiologists for incidental thyroid nodules seen on CT and MR imaging and to determine factors that influence reporting styles. MATERIALS AND METHODS: This is a retrospective study of patients with incidental thyroid nodules reported on CT and MR imaging between January and December 2011, identified by text search for "thyroid nodule" in all CT and MR imaging reports. The studies included CT and MR imaging scans of the neck, spine, and chest. Radiology reports were divided into those that mentioned the incidental thyroid nodules only in the "Findings" section versus those that reported the incidental thyroid nodules in the "Impression" section as well, because this latter reporting style gives more emphasis to the finding. Univariate and multivariate analyses were performed to identify radiologist, patient, and nodule characteristics that influenced reporting styles. RESULTS: Three hundred seventy-five patients met the criterion of having incidental thyroid nodules. One hundred thirty-eight (37%) patients had incidental thyroid nodules reported in the "Impression" section. On multivariate analysis, only radiologists' divisions and nodule size were associated with reporting in "Impression." Chest radiologists and neuroradiologists were more likely to report incidental thyroid nodules in the "Impression" section than their abdominal imaging colleagues, and larger incidental thyroid nodules were more likely to be reported in "Impression" (P ≤ .03). Seventy-three percent of patients with incidental thyroid nodules of ≥20 mm were reported in the "Impression" section, but higher variability in reporting was seen for incidental thyroid nodules measuring 10-14 mm and 15-19 mm, which were reported in "Impression" for 61% and 50% of patients, respectively. CONCLUSIONS: Reporting practices for incidental thyroid nodules detected on CT and MR imaging are predominantly influenced by nodule size and the radiologist's subspecialty. Reporting was highly variable for nodules measuring 10-19 mm; this finding can be partially attributed to different reporting styles among radiology subspecialty divisions. The variability demonstrated in this study further underscores the need to develop CT and MR imaging practice guidelines with the goal of standardizing reporting of incidental thyroid nodules and thereby potentially improving the consistency and quality of patient care.

Computed tomography findings in liver fibrosis and cirrhosis.

PRINCIPLES: Computed tomography (CT) is inferior to the fibroscan and laboratory testing in the noninvasive diagnosis of liver fibrosis. On the other hand, CT is a frequently used diagnostic tool in modern medicine. The auxiliary finding of clinically occult liver fibrosis in CT scans could result in an earlier diagnosis. The aim of this study was to analyse quantifiable direct signs of liver remodelling in CT scans to depict liver fibrosis in a precirrhotic stage. METHODS: Retrospective review of 148 abdominal CT scans (80 liver cirrhosis, 35 precirrhotic fibrosis and 33 control patients). Fibrosis and cirrhosis were histologically proven. The diameters of the three main hepatic veins were measured 1-2 cm before their aperture into the inferior caval vein. The width of the caudate and the right hepatic lobe were divided, and measured horizontally at the level of the first bifurcation of the right portal vein in axial planes (caudate-right-lobe ratio). A combination of both (sum of liver vein diameters divided by the caudate-right lobe ratio) was defined as the ld/crl ratio. These metrics were analysed for the detection of liver fibrosis and cirrhosis. RESULTS: An ld/crl-r <24 showed a sensitivity of 83% and a specificity of 76% for precirrhotic liver fibrosis. Liver cirrhosis could be detected with a sensitivity of 88% and a specificity of 82% if ld/crl-r <20. CONCLUSION: An ld/crl-r <24 justifies laboratory testing and a fibroscan. This could bring forward the diagnosis and patients would profit from early treatment in a potentially reversible stage of disease.

An almond-enriched diet increases plasma α-tocopherol and improves vascular function but does not affect oxidative stress markers or lipid levels.

Vascular dysfunction is one of the major causes of cardiovascular (CV) mortality and increases with age. Epidemiological studies suggest that Mediterranean diets and high nut consumption reduce CV disease risk and mortality while increasing plasma α-tocopherol. Therefore, we have investigated whether almond supplementation can improve oxidative stress markers and CV risk factors over 4 weeks in young and middle-aged men. Healthy middle-aged men (56 ± 5.8 years), healthy young men (22.1 ± 2.9 years) and young men with two or more CV risk factors (27.3 ± 5 years) consumed 50 g almond/day for 4 weeks. A control group maintained habitual diets over the same period. Plasma α-tocopherol/cholesterol ratios were not different between groups at baseline and were significantly elevated by almond intervention with 50 g almond/day for 4 weeks (p < 0.05). Plasma protein oxidation and nitrite levels were not different between groups whereas, total-, HDL- and LDL-cholesterols and triglycerides were significantly higher in healthy middle-aged and young men with CV risk factors but were not affected by intake. In the almond-consuming groups, flow-mediated dilatation (FMD) improved and systolic blood pressure reduced significantly after 50 g almonds/day for 4 weeks, but diastolic blood pressure reduced only in healthy men. In conclusion, a short-term almond-enriched diet can increase plasma α-tocopherol and improve vascular function in asymptomatic healthy men aged between 20 and 70 years without any effect on plasma lipids or markers of oxidative stress.

An exponential growth in incidence of thyroid cancer: trends and impact of CT imaging.

BACKGROUND AND PURPOSE: Workup of incidental thyroid nodules detected on CT imaging could be contributing to the increased diagnosis of small thyroid cancers. The purpose of this study was to evaluate recent trends in the incidence of thyroid cancer, and to determine the relationship between annual CT imaging volume and rate of thyroid cancer diagnosis. MATERIALS AND METHODS: This retrospective cohort study used data bases for thyroid cancer and CT imaging volume. Thyroid cancer data from 1983-2009 were obtained from the Surveillance, Epidemiology, and End Results data base. National Council of Radiation Protection and Measurements Report No. 160 provided data on hospital and nonhospital CT imaging volume for 1993-2006. Trends in thyroid cancer were modeled for overall incidence on the basis of patient age, tumor histologic features, and tumor size and stage. Linear regression analysis was performed to evaluate the strength of the relationship between annual CT scan volume and the incidence of thyroid cancer by tumor size and histologic type. RESULTS: In 2009, the incidence of thyroid cancer was 14 per 100,000, which represented a 1.9-fold increase compared with 2000. The growth in incidence was exponential compared with a minimal linear increase in thyroid cancer mortality rate. The subgroup with the greatest change was subcentimeter papillary carcinoma, with doubling in incidence approximately every 6.2 years. The linear relationship between annual CT scan volume and the incidence of subcentimeter papillary carcinoma was very strong (R(2) = 0.98; P < .0001). CONCLUSIONS: The incidence of subcentimeter papillary carcinoma is growing at an exponential rate without significant change in mortality rate. The strong linear relationship between new cases of subcentimeter papillary carcinomas and the number of CT scans per year suggests that an increase in CT scans may increase the detection of incidental thyroid cancers.

Prevalence of the polar vessel sign in parathyroid adenomas on the arterial phase of 4D CT.

BACKGROUND AND PURPOSE: The "polar vessel" sign has been previously described on sonography of parathyroid adenomas. We estimated the 4D CT prevalence of the polar vessel sign and determined features of parathyroid adenomas that are associated with this sign. MATERIALS AND METHODS: Twenty-eight consecutive patients with parathyroid adenomas underwent 4D CT between 2008 and 2012 at 2 institutions. 4D CT images were reviewed for the presence of the polar vessel sign and a second vascular finding of an enlarged ipsilateral inferior thyroid artery. The polar vessel sign was correlated with adenoma weight and size and arterial phase CT attenuation. RESULTS: Thirty-two parathyroid adenomas in 28 patients were studied, with a mean adenoma weight of 0.66 ± 0.65 g, a mean maximal CT diameter of 11.1 ± 4.9 mm, and a mean arterial attenuation of 148 ± 47 HU. The polar vessel sign was seen in 20/32 (63%) adenomas. Adenomas with a polar vessel had higher arterial phase attenuation than adenomas without a polar vessel (163 and 122 HU, respectively, P < .01). Size and weight were not significantly different for adenomas with and without polar vessels. An enlarged inferior thyroid artery was seen in only 2/28 (7%) patients with unilateral disease. CONCLUSIONS: The polar vessel sign was present in nearly two-thirds of parathyroid adenomas on 4D CT and was more likely to be present in adenomas that had greater arterial phase enhancement. This sign can be used along with enhancement characteristics to increase the radiologist's confidence that a visualized lesion is a parathyroid adenoma rather than a thyroid nodule or lymph node.

Incidental thyroid nodules on CT: evaluation of 2 risk-categorization methods for work-up of nodules.

BACKGROUND AND PURPOSE: Thyroid nodules are common incidental findings on CT, but there are no clear guidelines regarding their further diagnostic work-up. This study compares the performance of 2 risk-categorization methods of selecting CT-detected incidental thyroid nodules for work-up. MATERIALS AND METHODS: The 2 categorization methods were method A, based on nodule size ≥10 mm, and method B, a 3-tiered system based on aggressive imaging features, patient age younger than 35 years or nodule size of ≥15 mm. In part 1, the 2 categorization methods were applied to thyroid cancers in the SEER data base of the National Cancer Institute to compare the cancer capture rates and survival. In part two, 755 CT neck scans at our institution were retrospectively reviewed for the presence of ITNs of ≥5 mm, and the same 2 categorization methods were applied to the CT cases to compare the number of patients who would theoretically meet the criteria for work-up. Comparisons of proportions of subjects captured under methods A and B were made by using the McNemar test. RESULTS: For 84,720 subjects in the SEER data base, methods A and B each captured 74% (62,708/84,720 and 62,586/84,720, respectively) of malignancies. SEER subjects who would not have met the criteria for further work-up by both methods had equally excellent 10-year cause-specific and relative survival of >99%. For part 2, the prevalence of ITNs of ≥5 mm at our institution was 133/755 (18%). The number of ITNs that would be recommended for work-up by method A was 57/133 (43%) compared with 31/133 (23%) for method B (P < .0005). CONCLUSIONS: Compared with using a 10-mm cutoff, the 3-tiered risk-stratification method identified fewer ITNs for work-up but captured the same proportion of cancers in a national data base and showed no difference in missing high-mortality cancers.

Using FDG-PET to measure early treatment response in head and neck squamous cell carcinoma: quantifying intrinsic variability in order to understand treatment-induced change.

BACKGROUND AND PURPOSE: Quantification of both baseline variability and intratreatment change is necessary to optimally incorporate functional imaging into adaptive therapy strategies for HNSCC. Our aim was to define the baseline variability of SUV on FDG-PET scans in patients with head and neck squamous cell carcinoma and to compare it with early treatment-induced SUV change. MATERIALS AND METHODS: Patients with American Joint Committee on Cancer stages III-IV HNSCC were imaged with 2 baseline PET/CT scans and a third scan after 1-2 weeks of curative-intent chemoradiation. SUVmax and SUVmean were measured in the primary tumor and most metabolically active nodal metastasis. Repeatability was assessed with Bland-Altman plots. Mean percentage differences (%ΔSUV) in baseline SUVs were compared with intratreatment %ΔSUV. The repeatability coefficient for baseline %ΔSUV was compared with intratreatment %ΔSUV. RESULTS: Seventeen patients had double-baseline imaging, and 15 of these patients also had intratreatment scans. Bland-Altman plots showed excellent baseline agreement for nodal metastases SUVmax and SUVmean, but not primary tumor SUVs. The mean baseline %ΔSUV was lowest for SUVmax in nodes (7.6% ± 5.2%) and highest for SUVmax in primary tumor (12.6% ± 9.2%). Corresponding mean intratreatment %ΔSUVmax was 14.5% ± 21.6% for nodes and 15.2% ± 22.4% for primary tumor. The calculated RC for baseline nodal SUVmax and SUVmean were 10% and 16%, respectively. The only patient with intratreatment %ΔSUV above these RCs was 1 of 2 patients with residual disease after CRT. CONCLUSIONS: Baseline SUV variability for HNSCC is less than intratreatment change for SUV in nodal disease. Evaluation of early treatment response should be measured quantitatively in nodal disease rather than the primary tumor, and assessment of response should consider intrinsic baseline variability.

Adjuvant chemotherapy with six cycles of AC regimen versus three cycles of AC regimen followed by three cycles of Paclitaxel in node-positive breast cancer.

CONTEXT: Antracycline-Cyclophosphamide (AC) along with Paclitaxel/Docetaxel, either in combination or sequential regimens, is showing superior results than Anthracycline-containing regimens. AIMS: This study was designed to determine whether adding Paclitaxel to a standard adjuvant chemotherapy regimen AC for breast cancer patients would prolong the time to recurrence and survival. SETTINGS AND DESIGN: Randomized, prospective, open-labeled, single-institutional study. MATERIALS AND METHODS: Fifty stage II breast cancer patients accruing 25 patients in each arm, treated between July 2007 and January 2010, were included in the study. Initial surgical treatment was Modified Radical Mastectomy. Systemic therapy was to have begun within 4-6 weeks of the patient's surgery. In the control arm, all the patients were treated with six cycles of adjuvant chemotherapy with AC regimen repeated at an interval of 3 weeks. For the study arm, the patients received adjuvant chemotherapy with three cycles of AC regimen followed by three cycles of Paclitaxel, repeated at an interval of 3 weeks. All the patients of both the arms received locoregional external beam radiotherapy (EBRT) after the entire course of chemotherapy. All the hormone receptor-positive patients received Tamoxifen. STATISTICAL ANALYSIS USED: Statistical analysis was performed using the chi-square test and the Kaplan Meier survival analysis with the log-rank (Mantel-Cox) test. RESULTS: Adding Paclitaxel to AC resulted in a statistically significant disease-free survival. The overall survival was also improved significantly. The toxicity profile in both the arms was comparable. CONCLUSIONS: In early and node-positive breast cancer, the addition of three cycles of Paclitaxel after completion of three cycles of AC improves the disease-free and overall survival.

Effectiveness of skin cancer screening programmes.

Skin cancer, nonmelanoma skin cancer (NMSC) and cutaneous malignant melanoma (CMM), is the most frequent cancer worldwide. It is amenable to early detection, and screening for skin cancer has the potential to reduce mortality and morbidity. However, there are no recommendations for population-based skin cancer screening programmes due to the lack of evidence for the effectiveness from epidemiological studies. In 2008 the first nationwide screening programme for NMSC and CMM in the world was established in Germany. The decision for implementing such a programme was based on the results and evidence of a pilot study that was conducted from 2003 to 2004. The pilot study revealed that a population-based screening programme for skin cancer is feasible and effective. Careful evaluation of the nationwide programme is crucial to generate strong evidence for long-term public health benefits.

CT-guided lumbar nerve root injections: are we using the correct radiation dose settings?

BACKGROUND AND PURPOSE: Selecting a lower tube current for CT fluoroscopic spine injections is a method of radiation dose reduction. Ideally tube current should be tailored to the patient's body habitus, but a greater influence on tube current may be the proceduralist's personal preference. The purpose of this study was to compare tube current and fluoroscopy time of different proceduralists for lumbar spine CT-guided selective nerve root blocks, and to correlate image quality to patient diameter and tube current. MATERIALS AND METHODS: Eighty CT-guided SNRBs performed by 4 proceduralists were retrospectively reviewed for tube current and fluoroscopy time. Patient body habitus was evaluated by measuring anteroposterior diameters on scout images. Image quality was evaluated objectively and subjectively: noise was measured in the psoas muscle and images were graded on a 3-point scale. RESULTS: The mean tube current was 59 ± 20 mA and mean fluoroscopy time was 10.4 ± 7.5 seconds. The mean tube current between proceduralists differed by almost 2-fold, and there was greater than 2-fold difference in mean fluoroscopy time (P < .0001 and .01, respectively). Mean AP body size was 27 ± 5 cm. When categoric data of tube current and AP diameter were analyzed, only AP diameter was a statistically significant variable influencing image noise (P = .009). Twenty of 23 patients with AP diameter ≤30 cm had adequate to excellent image quality, even with lower tube current of ≤40 mA. CONCLUSIONS: Wide variability in tube current selection between proceduralists calls for a more objective method of selecting tube current to minimize radiation dose. Body size, measured by AP diameter, had the greatest influence on image quality. This could be used to identify patients for lower tube current selection.

SU-E-I-47: Comparison of Risks for Two Medical Imaging Procedures.

PURPOSE: Radiologists may need to decide which type of image procedure is most appropriate for a particular patient. One factor relevant in making this decision is the relative risk of secondary cancers due to each relevant procedure. Differences in the risk posed by each method are not just due to the total radiation dose imparted by each procedure, but also the distribution of absorbed dose across various organs in the imaging procedure. Two imaging procedures with the same total radiation dose may pose different risks of differential sensitivity to radiation across organs. METHODS: New methods of radiation dosimetry enable us to estimate the dose distribution across organs in individual patients. We propose a measure of the relative risk of two medical imaging procedures derived from the hazard function of cancer incidence. The relative risk measure is shown to approximately equal to a weighted sum of the dose difference in each organ. The weights are proportional to organ specific incidence rates. The measure is also sensitive to factors such as the patient's age at exposure to radiation, the attained age and gender, as well as the incidence characteristics of the population to which the patient belongs. We propose to quantify the effects of these factors using information from publically available SEER database for US based patients as well as the LSS study of atomic bomb survivors. The method is illustrated by application to a study comparing chest and abdominal CT scans for a group of pediatric patients. RESULTS: Fig. 1 shows higher absolute relative risk for those exposed at younger ages, with chest scans being riskier for females while abdominal scans were riskier for males. At higher ages, the relative risk is approximately equal. CONCLUSIONS: Relative risks can quantify risks comparisons between imaging procedures.

SU-E-T-275: Dose Verification in a Small Animal Image-Guided Radiation Therapy X-Ray Machine: A Dose Comparison between TG-61 Based Look-Up Table and MOSFET Method for Various Collimator Sizes.

PURPOSE: To verify the accuracy of TG-61 based dosimetry with MOSFET technology using a tissue-equivalent mouse phantom. METHODS: Accuracy of mouse dose between a TG-61 based look-up table was verified with MOSFET technology. The look-up table followed a TG-61 based commissioning and used a solid water block and radiochromic film. A tissue-equivalent mouse phantom (2 cm diameter, 8 cm length) was used for the MOSFET method. Detectors were placed in the phantom at the head and center of the body. MOSFETs were calibrated in air with an ion chamber and f-factor was applied to derive the dose to tissue. In CBCT mode, the phantom was positioned such that the system isocenter coincided with the center of the MOSFET with the active volume perpendicular to the beam. The absorbed dose was measured three times for seven different collimators, respectively. The exposure parameters were 225 kVp, 13 mA, and an exposure time of 20 s. RESULTS: For a 10 mm, 15 mm, and 20 mm circular collimator, the dose measured by the phantom was 4.3%, 2.7%, and 6% lower than TG-61 based measurements, respectively. For a 10 × 10 mm, 20 × 20 mm, and 40 × 40 mm collimator, the dose difference was 4.7%, 7.7%, and 2.9%, respectively. CONCLUSIONS: The MOSFET data was systematically lower than the commissioning data. The dose difference is due to the increased scatter radiation in the solid water block versus the dimension of the mouse phantom leading to an overestimation of the actual dose in the solid water block. The MOSFET method with the use of a tissue- equivalent mouse phantom provides less labor intensive geometry-specific dosimetry and accuracy with better dose tolerances of up to ± 2.7%.

Intra subject variation and correlation of motor potentials evoked by transcranial magnetic stimulation.

BACKGROUND: Characterising intra and inter-subject variability of motor-evoked potential (MEP) measurements from transcranial magnetic stimulation (TMS) is key to its development as a diagnostic tool. METHODS: We performed three experiments to elucidate MEP variability within subjects: (i) repeated measurements at different levels of stimulation and muscle activation, (ii) simultaneous measurements at pairs of ipsilateral and contralateral muscles, (iii) simultaneous measurements of contralateral muscles when one is activated. RESULTS: Cube root transformation of MEP data produces approximately constant coefficient of variation with Gaussian distribution and no significant autocorrelation between repeat measurements. After adjustment of intersubject variability, correlation between simultaneous muscle pairs was insignificant (p = 0.36). Highly significant effects were observed due to increase in intensity of stimulation: (0.07, 0.23) mV, p < 0.0001, muscle type: (p < 0.009) and activation of ipsilateral muscle: (0.10, 0.49) mV, p < 0.0001. CONCLUSION: Corticospinal effect is dominated by intersubject variability in simultaneous measurements on normal population.