Kyungmouk Steve Lee

Role of External Beam Radiotherapy in Patients With Advanced or Recurrent Nonanaplastic Thyroid Cancer: Memorial Sloan-Kettering Cancer Center Experience

PURPOSEnExternal beam radiotherapy (EBRT) plays a controversial role in the management of nonanaplastic thyroid cancer. We reviewed our institutions outcomes in patients treated with EBRT for advanced or recurrent nonanaplastic thyroid cancer.nnnMETHODS AND MATERIALSnBetween April 1989 and April 2006, 76 patients with nonanaplastic thyroid cancer were treated with EBRT. The median follow-up for the surviving patients was 35.3 months (range, 4.2-178.4). The lesions were primarily advanced and included Stage T2 in 5 (7%), T3 in 5 (7%), and T4 in 64 (84%) patients. Stage N1 disease was present in 60 patients (79%). Distant metastases before EBRT were identified in 27 patients (36%). The median total EBRT dose delivered was 6,300 cGy. The histologic features examined included medullary in 12 patients (16%) and nonmedullary in 64 (84%). Of the 76 patients, 71 (93%) had undergone surgery before RT, and radioactive iodine treatment was used in 56 patients (74%).nnnRESULTSnThe 2- and 4-year overall locoregional control rate for all histologic types was 86% and 72%, respectively, and the 2- and 4-year overall survival rate for all patients was 74% and 55%, respectively. No significant differences were found in locoregional control, overall survival, or distant metastases-free survival for patients with complete resection, microscopic residual disease, or gross residual disease. Grade 3 acute mucositis and dysphagia occurred in 14 (18%) and 24 (32%) patients, respectively. Late adverse toxicity was notable for percutaneous endoscopic gastrostomy tube use in 4 patients (5%).nnnCONCLUSIONnThe results of our study have shown that EBRT is effective for locoregional control of selected locally advanced or recurrent nonanaplastic thyroid malignancies, with acceptable acute toxicity.

Percutaneous Ablation of Peribiliary Tumors with Irreversible Electroporation

PURPOSEnTo assess biliary complications after irreversible electroporation (IRE) ablation of hepatic tumors located < 1 cm from major bile ducts.nnnMATERIALS AND METHODSnA retrospective review was conducted of all percutaneous IRE ablations of hepatic tumors within 1 cm of the common, left, or right hepatic ducts at a single institution from January 2011 to September 2012. Computed tomography imaging performed before and after treatment was examined for evidence of bile duct dilatation, stricture, or leakage. Serum bilirubin and alkaline phosphatase levels were analyzed for evidence of biliary injury.nnnRESULTSnThere were 22 hepatic metastases in 11 patients with at least one tumor within 1 cm of the common, left, or right hepatic duct that were treated with IRE ablations in 15 sessions. Median tumor size treated was 3.0 cm (mean, 2.8 cm ± 1.2, range, 1.0-4.7 cm). Laboratory values obtained after IRE were considered abnormal after four treatment sessions in three patients (bilirubin, 2.6-17.6 mg/dL; alkaline phosphatase, 130-1,035 U/L); these abnormal values were transient in two sessions. Two patients had prolonged elevation of values, and one required stent placement; both of these conditions appeared to be secondary to tumor progression rather than bile duct injury.nnnCONCLUSIONSnThis clinical experience suggests that IRE may be a treatment option for centrally located liver tumors with margins adjacent to major bile ducts where thermal ablation techniques are contraindicated. Further studies with extended follow-up periods are necessary to establish the safety profile of IRE in this setting.

Assessing neuromuscular disease with multifrequency electrical impedance myography

Electrical impedance myography (EIM) is a noninvasive technique for neuromuscular assessment in which low‐intensity alternating current is applied to a muscle and the consequent surface voltage patterns are evaluated. Previous work using a single frequency of 50 kHZ has demonstrated quantitative correlation of EIM parameters with disease status. In this investigation we examined the use of multifrequency EIM, studying a prototypical neurogenic disease (amyotrophic lateral sclerosis, ALS) and myopathic disorder (inflammatory myopathy, IM). Eleven ALS patients, 7 IM patients, and 46 normal subjects participated in the study. Although disease‐specific patterns were not identified such that IM could be differentiated from ALS, impedance vs. frequency patterns for diseased subjects differed substantially from those of the age‐matched normal subjects, with the greatest alterations occurring in the most severe cases. Multifrequency EIM may be well‐suited to serve as an easily applied technique to assess disease severity in a variety of neuromuscular conditions. Muscle Nerve, 2006

Electrical impedance myography in the bedside assessment of inflammatory myopathy

Electrical impedance myography (EIM) is a new technique with potential for the noninvasive bedside assessment of myopathy. EIM was performed on the quadriceps of 10 patients with inflammatory myopathy and 10 normal subjects. The major EIM parameter, the spatially averaged phase, was 35% lower in the myositis patients and correlated with whole-body (r = 0.765, p = 0.01) and quadriceps (r = 0.673, p = 0.03) strength.

Electrical impedance myography in the detection of radiculopathy

Electrical impedance myography (EIM) is a new bioimpedance‐based technique for neuromuscular disease assessment. Past work has focused on EIM in the evaluation of diffuse diseases (such as myopathy). In this study, the methods most basic form, linear‐EIM, was used for the assessment of restricted radiculopathic disease. Ten normal subjects and 10 patients with unilateral cervical or lumbosacral radiculopathy, diagnosed by electromyography and clinical criteria, were enrolled. Linear‐EIM was performed bilaterally on all individuals, and comparisons with the major outcome variable, θavg, were made. In normal subjects, side‐to‐side differences in θavg averaged 0.64% and were no greater than 15.9% in magnitude. In the 10 patients with radiculopathy, θavgwas consistently lower in the affected extremity, with a mean side‐to‐side difference of 15.3%, but ranging as low as 72.3%; there was a tendency for muscles with more prominent chronic neurogenic change to show greater relative reductions in θavg. These findings support the potential utility of EIM in assessment of localized neuromuscular disease. Muscle Nerve, 2005

Effects of age on muscle as measured by electrical impedance myography.

Electrical impedance myography (EIM) is a painless and non-invasive technique for the assessment of muscle which we apply here to the effects of normal aging. The paper presents a cross-sectional analysis of EIM data from the quadriceps and tibialis anterior of 100 healthy subjects (44 men, 56 women, ages 18-90 years). The principal EIM parameter, the spatially averaged phase theta(avg), shows a roughly quadratic reduction with increasing age, declining more steeply beyond 60 years. The correlation was stronger in men (quadriceps: r2 = 0.68 for men, 0.52 for women; tibialis anterior: r2 = 0.74 for men, 0.38 for women; p < 0.001 throughout). Additionally, four subjects (age greater than 75 years) were asked to return for repeat testing several years after their initial assessment. These longitudinal results qualitatively confirm the cross-sectional data, though with greater reductions in theta(avg) at high age. The findings of this study support the potential use of EIM as a simple and effort-independent test of muscle health in the elderly.

Distinguishing Benign and Life-Threatening Pneumatosis Intestinalis in Patients With Cancer by CT Imaging Features

OBJECTIVEnThe purpose of this study is to determine the overall proportion of clinically worrisome and benign pneumatosis intestinalis (PI) occurring in patients with cancer and to evaluate associated risk factors and CT features.nnnMATERIALS AND METHODSnWe retrospectively studied the CT examinations of 84 patients treated at our tertiary cancer center. Reviewers who were blinded to clinical data and classification analyzed PI in terms of location, pattern (linear, cystic, or both), and associated CT features, including pneumoperitoneum, portomesenteric venous air, bowel wall thickening, bowel dilatation, and ascites. On the basis of the review of clinical information and criteria derived from prior literature, the cases were classified as clinically worrisome PI (underlying bowel disease) or benign PI (diagnosis of exclusion that resolved on follow-up imaging without targeted therapy). Clinical factors reviewed included age, sex, cancer type, steroid use, and chemotherapy administration.nnnRESULTSnForty-seven patients were classified as having benign PI (56%) and the remainder as having clinically worrisome PI (44%). The following imaging features correlated significantly with clinically worrisome PI: bowel wall thickening (p < 0.001), mesenteric stranding (p < 0.001), ascites (p < 0.001), bowel dilatation (p = 0.004), location confined to small bowel (p = 0.012), and portomesenteric venous gas (p = 0.02). Benign PI was significantly associated with PI confined to the colon (p = 0.004).nnnCONCLUSIONnBenign PI was slightly more prevalent than clinically worrisome PI in our cohort of patients with cancer. The presence of certain CT features (mesenteric stranding, bowel wall thickening, and ascites) and the location of PI may be indicators of more significant bowel disease and, therefore, of clinically worrisome cases. There was no statistical significance achieved for nonimaging clinical factors.

Test–retest reproducibility of 50 kHz linear-electrical impedance myography

OBJECTIVEnElectrical impedance myography (EIM) is a method for evaluating muscle in which high-frequency, low-intensity alternating current is applied to a body region and the resulting surface voltage pattern over a muscle of interest is measured. In this study, the reproducibility for the simplest of these techniques, 50 kHz linear-EIM, was assessed for three muscles.nnnMETHODSnFifty kilohertz linear-EIM was performed on the biceps, quadriceps, and tibialis anterior of 30 normal subjects ranging in age from 21 to 90 years, and the major outcome variable, the spatially averaged phase (thetaavg), measured. The measurements were repeated within 250 days and comparisons between the two data sets made.nnnRESULTSnReproducibility, as measured by the intraclass correlation coefficients for all three muscles, was very high at 0.970, 0.971, and 0.938 for biceps, quadriceps, and tibialis anterior, respectively. Variability between measurements was on average 4.2% for all muscle combined, with an upper limit of 16.8%.nnnCONCLUSIONSnFifty kilohertz linear-EIM demonstrates excellent test-retest reproducibility.nnnSIGNIFICANCEnThese results support the view that 50 kHz linear-EIM has the potential to be used as a simple, fast, and non-invasive measurement for the assessment of disease status, either as part of individual patient care or as a surrogate outcome measure in clinical trials work.

Impact of skin-subcutaneous fat layer thickness on electrical impedance myography measurements: An initial assessment

OBJECTIVEnTo determine the impact of skin-subcutaneous fat layer thickness on electrical impedance myography (EIM) measurements.nnnMETHODSnLinear 50 kHz EIM was performed on quadriceps of 62 healthy subjects (mean age 52.2+/-20.6 years) with a wide variety of skin-subcutaneous fat layer (SFL) thicknesses, as measured by ultrasound. Correlations were sought between the main EIM outcome parameter phase (theta) and SFL thickness. A multiple regression analysis was also performed for theta with SFL thickness and age as independent variables.nnnRESULTSnMean skin-fat thickness was significantly different (p<0.01) between men (0.76+/-0.23 cm) and women (1.43+/-0.51 cm). Neither linear nor quadratic fits produced significant correlations between theta and SFL thickness. A significant but weak positive correlation (r(2)=0.14, p<0.05) was seen between age and SFL thickness in women, but not in men. A strong negative correlation between age and theta was observed for both men (r(2)=0.48, p<0.01) and women (r(2)=0.68, p<0.01). In multiple regression analysis, age but not SFL thickness was found to have a significant association with theta.nnnCONCLUSIONSnSFL thickness does not contribute substantially to the phase measured by linear-EIM.nnnSIGNIFICANCEnEIM data can be interpreted confidently in individuals with varying SFL thickness.

Electrical impedance myography: Transitioning from human to animal studies

OBJECTIVEnTo determine the feasibility of performing electrical impedance myography (EIM) in rats.nnnMETHODSnEIM was performed on the hamstring muscles of 6 healthy adult rats with applied frequencies of 2-300 kHz. Studies were performed over a 6-week period, with 3 rats having recordings made from the skin (surface EIM) and 3 with recordings directly from the muscle (direct-muscle EIM). In addition, sciatic nerve crush was performed on one rat and comparisons made pre- and post-injury. Reactance and resistance were measured and the primary outcome variable, the phase angle (theta), calculated.nnnRESULTSnEIM patterns in the rat hamstring muscles were qualitatively similar to those observed in human subjects. This held true for both surface and direct-muscle recordings, although direct-muscle data appeared less repeatable. Sciatic nerve crush data in the single rat showed a dramatic reduction in phase and a relative loss of frequency-dependence.nnnCONCLUSIONSnEIM data similar to that obtained from human subjects can be acquired from rat muscles with surface recordings proving more consistent and easier to obtain than direct-muscle recordings. Changes seen with sciatic nerve crush mirror those seen in patients with neurogenic injury.nnnSIGNIFICANCEnThese results support the possibility of performing EIM on rat models of neuromuscular disease.