Post-radiation primary hypothyroidism in patients with head and neck cancer: External validation of thyroid gland dose-volume constraints with long-term endocrine outcomes.

BACKGROUND: Post-radiation primary hypothyroidism is a common late complication in head and neck cancer (HNC) survivors. No radiation dose-volume constraint of the thyroid gland has been externally validated for predicting long-term thyroid function outcomes. MATERIALS AND METHODS: This external validation study evaluated the diagnostic properties of 22 radiation dose-volume constraints of the thyroid gland proposed in the literature. Radiation dosimetric data from 488 HNC patients who underwent neck irradiation from January 2013 to December 2015 at two tertiary oncology centers were reviewed. The diagnostic metrics of candidate constraints were computed by inverse probability of censoring weighting and compared using time-dependent receiver operating characteristic (ROC) curves with death designated as a competing event. Multivariable regression analyses were performed using the Fine-Gray sub-distribution hazard model. RESULTS: Over a median follow-up period of 6.8 years, 205 (42.0 %) patients developed post-radiation primary hypothyroidism. The thyroid volume spared from 60 Gy (VS60) had the largest area under ROC curve of 0.698 at 5 years after radiotherapy. Of all evaluated constraints, VS60 at a cutoff value of 10 cc had the highest F-score of 0.53. The 5-year hypothyroidism risks of patients with thyroid VS60 ≥ 10 cc and < 10 cc were 14.7 % and 38.2 %, respectively (p < 0.001). The adjusted sub-hazard ratio for post-radiation primary hypothyroidism for VS60 < 10 cc was 1.87 (95 % confidence interval, 1.22-2.87; p < 0.001). CONCLUSION: Thyroid VS60 is the best radiation dose-volume parameter to predict the long-term risk of primary hypothyroidism in patients with HNC who underwent neck irradiation. VS60 ≥ 10 cc is a robust constraint that limits the 5-year primary hypothyroidism risk to less than 15 % and should be routinely employed during radiotherapy optimization.

Dose-volume predictors of post-radiation primary hypothyroidism in head and neck cancer: A systematic review.

BACKGROUND AND PURPOSE: This systematic review aims to identify radiation dose-volume predictors of primary hypothyroidism after radiotherapy in patients with head and neck cancer (HNC). MATERIALS AND METHODS: We performed a systematic literature search of Medline, EMBASE and Web of Science from database inception to July 1, 2021 for articles that discuss radiation dose-volume predictors of post-radiation primary hypothyroidism in patients with HNC. Data on the incidence, clinical risk factors and radiation dose-volume parameters were extracted. A meta-analysis was performed using the random-effects model to estimate the pooled odds ratio (OR) of thyroid volume as a predictor of the risk of post-radiation hypothyroidism, adjusted for thyroid radiation dosimetry. RESULTS: Our search identified 29 observational studies involving 4,530 patients. With median follow-up durations ranging from 1.0 to 5.3 years, the average crude incidence of post-radiation primary hypothyroidism was 41.4 % (range, 10 %-57 %). Multiple radiation dose-volume parameters were associated with post-radiation primary hypothyroidism, including the thyroid mean dose (Dmean), minimum dose, V25, V30, V35, V45, V50, V30-60, VS45 and VS60. Thyroid Dmean and V50 were the most frequently proposed dosimetric predictors. The pooled adjusted OR of thyroid volume on the risk of post-radiation primary hypothyroidism was 0.89 (95 % confidence interval, 0.85-0.93; p < 0.001) per 1 cc increment. CONCLUSION: Post-radiation primary hypothyroidism is a common late complication after radiotherapy for HNC. Minimizing inadvertent exposure of the thyroid gland to radiation is crucial to prevent this late complication. Radiation dose-volume constraints individualized for thyroid volume should be considered in HNC radiotherapy planning.

A practical methodology to improve the dosimetric accuracy of MR-based radiotherapy simulation for brain tumors.

PURPOSE: To investigate the dosimetric accuracy of synthetic computed tomography (sCT) images generated by a clinically-ready voxel-based MRI simulation package, and to develop a simple and feasible method to improve the accuracy. METHODS: 20 patients with brain tumor were selected to undergo CT and MRI simulation. sCT images were generated by a clinical MRI simulation package. The discrepancy between planning CT and sCT in CT number and body contour were evaluated. To resolve the discrepancies, an sCT specific CT-relative electron density (RED) calibration curve was used, and a layer of pseudo-skin was created on the sCT. The dosimetric impact of these discrepancies, and the improvement brought about by the modifications, were evaluated by a planning study. Volumetric modulated arc therapy (VMAT) treatment plans for each patient were created and optimized on the planning CT, which were then transferred to the original sCT and the modified-sCT for dose re-calculation. Dosimetric comparisons and gamma analysis between the calculated doses in different images were performed. RESULTS: The average gamma passing rate with 1%/1 mm criteria was only 70.8% for the comparison of dose distribution between planning CT and original sCT. The mean dose difference between the planning CT and the original sCT were -1.2% for PTV D95 and -1.7% for PTV Dmax, while the mean dose difference was within 0.7 Gy for all relevant OARs. After applying the modifications on the sCT, the average gamma passing rate was increased to 92.2%. Mean dose difference in PTV D95 and Dmax were reduced to -0.1% and -0.3% respectively. The mean dose difference was within 0.2 Gy for all OAR structures and no statistically significant difference were found. CONCLUSIONS: The modified-sCT demonstrated improved dosimetric agreement with the planning CT. These results indicated the overall dosimetric accuracy and practicality of this improved MR-based treatment planning method.

Application of hypoglossal nerve constraint in definitive radiotherapy for nasopharyngeal carcinoma: A dosimetric feasibility study.

PURPOSE: Radiation-induced hypoglossal nerve palsy is an infrequent but debilitating late complication after definitive radiotherapy for head and neck cancers. D1cc < 74 Gy (equivalent dose in 2 Gy fractions, EQD2) has been proposed as a potential dose constraint that limits 8-year palsy risk to < 5%. This study sets to perform detailed dosimetric assessments on the applicability of this novel dose constraint in advanced nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: This is a retrospective single-institution dosimetry study. NPC radiotherapy plans were identified from an institutional database, with an aim to select 10 eligible cases. Bilateral hypoglossal nerves were retrospectively contoured following a standard atlas. Cases with either one, or both, hypoglossal nerves D1cc exceeded 74 Gy EQD2 were included. Dosimetry of hypoglossal nerves, planning target volumes (PTV) and normal structures before and after application of the new hypoglossal nerve constraint were compared and analyzed. RESULTS: Ten NPC cases were replanned. All hypoglossal nerve contours overlapped with high-dose PTV, predominantly at regions of gross nodal diseases. D1cc in 15 out of 20 hypoglossal nerves exceeded 74G y EQD2 at initial plans. All nerves fulfilled the pre-specified constraint of 74Gy EQD2 after re-plan. Median hypoglossal nerve D1cc reduced from 74.8Gy (range, 74.1 to 77.4Gy) to 73.5Gy (range, 72.4 to 74.0Gy) (p < 0.001), corresponded to a projected reduction in 8-year palsy risk from 5%-14% to 3%-5%. PTV V100 was maintained above 95% in all cases. Dose increments in near-maximum (D2) and decrements in near-minimum (D98) were < 1 Gy. Safety dosimetric parameters of standard head and neck organs-at-risk showed no significant changes. CONCLUSIONS: Hypoglossal nerve D1cc < 74 Gy EQD2 is a dosimetrically feasible constraint in definitive radiotherapy for NPC. Tumor target coverage and normal organ dosimetry were not compromised with its usage. Its routine application should be considered in definitive radiotherapy for head and neck cancers.

Radiation-induced hypoglossal nerve palsy after definitive radiotherapy for nasopharyngeal carcinoma: Clinical predictors and dose-toxicity relationship.

BACKGROUND AND PURPOSE: Radiation-induced hypoglossal nerve palsy is a debilitating and irreversible late complication after definitive radiotherapy for nasopharyngeal carcinoma (NPC) and other skull base tumors. This study sets to evaluate its incidence and clinical predictive factors, and to propose relevant dosimetric constraints for this structure to guide radiotherapy planning. MATERIALS AND METHODS: We undertook a retrospective review of 797 NPC patients who underwent definitive intensity-modulated radiotherapy (IMRT) between 2003 and 2011. Cumulative incidence and clinical predictors for radiation-induced hypoglossal nerve palsy were evaluated. Archived radiotherapy plans were retrieved and 330 independent hypoglossal nerves were retrospectively contoured following standardized atlas. Optimal threshold analyses of dosimetric parameters (Dmax, D0.5cc, D1cc, D2cc, Dmean) were conducted using receiver operating characteristic curves. Normal tissue complication probability was generated with logistic regression modeling. RESULTS: With a median follow-up of 8.1 years, sixty-nine (8.7%) patients developed radiation-induced hypoglossal nerve palsy. High radiotherapy dose, premorbid diabetes, advanced T-stage and radiological hypoglossal canal involvement were independent clinical risk factors. Maximum dose received by 1 cc volume (D1cc) was the best predictor for the development of radiation-induced nerve palsy (AUC = 0.826) at 8 years after IMRT. Hypoglossal nerves with D1cc of 74 Gy EQD2 had an estimated palsy risk of 4.7%. Nerves with D1cc <74 Gy EQD2 had significantly lower risk of palsy than those ≥74 Gy EQD2 (2.4% vs 20.8%, p <0.001). CONCLUSION: Incidence of radiation-induced hypoglossal nerve palsy was high after definitive IMRT for NPC. D1cc <74 Gy EQD2 can serve as a useful dose constraint to adopt during radiotherapy planning to limit palsy risk to <5% at 8 years after IMRT.

MALDI-TOF-MS Assay to Detect the Hemizygous 22q11.2 Deletion in DNA from Dried Blood Spots.

BACKGROUND: A hemizygous deletion of 1.5-3 Mb in 22q11.2 causes a distinct clinical syndrome with variable congenital defects. Current diagnostic methods use fluorescent in situ hybridization (FISH) or comparative genomic hybridization by microarray to detect the deletion. Neither method is suitable for newborn screening (NBS), since they cannot be performed on dried blood spots (DBS). We developed a MALDI-TOF-MS assay that uses DBS to measure the hemizygous deletion of UFD1L, located within the 22q11.2 region. METHODS: We used DBS from 54 affected patients, previously tested by FISH or microarray, and 100 cord blood samples to evaluate the performance of the MALDI-TOF-MS assay. With a single primer pair, a 97-base oligonucleotide within UFD1L was amplified, as was a sequence on chromosome 18 that differs by 2 nucleotides. A multiplexed, single-base extension reaction created allele-specific products for MALDI-TOF-MS detection. The products were spotted onto a silicon chip, and the height of the spectral peaks identified the relative amounts of target and reference gene. RESULTS: The median ratio of the spectral peak for each UFD1L target:reference base was 0.96 and 0.99 for controls, compared with 0.35 and 0.53 for 22q11 deletion syndrome patients. There was 100% concordance between FISH/microarray and MALDI-TOF-MS in all patients with 22q11.2 deletion syndrome. CONCLUSIONS: This method can be reliably performed with DBS and is suitable for high sample throughput. This assay may be considered for use in population-based NBS for 22q11.2 deletion.

Newborn blood spot screening test using multiplexed real-time PCR to simultaneously screen for spinal muscular atrophy and severe combined immunodeficiency.

BACKGROUND: Spinal muscular atrophy (SMA) is a motor neuron disorder caused by the absence of a functional survival of motor neuron 1, telomeric (SMN1) gene. Type I SMA, a lethal disease of infancy, accounts for the majority of cases. Newborn blood spot screening (NBS) to detect severe combined immunodeficiency (SCID) has been implemented in public health laboratories in the last 5 years. SCID detection is based on real-time PCR assays to measure T-cell receptor excision circles (TREC), a byproduct of T-cell development. We modified a multiplexed real-time PCR TREC assay to simultaneously determine the presence or absence of the SMN1 gene from a dried blood spot (DBS) punch in a single reaction well. METHOD: An SMN1 assay using a locked nucleic acid probe was initially developed with cell culture and umbilical cord blood (UCB) DNA extracts, and then integrated into the TREC assay. DBS punches were placed in 96-well arrays, washed, and amplified directly using reagents specific for TREC, a reference gene [ribonuclease P/MRP 30kDa subunit (RPP30)], and the SMN1 gene. The assay was tested on DBS made from UCB units and from peripheral blood samples of SMA-affected individuals and their family members. RESULTS: DBS made from SMA-affected individuals showed no SMN1-specific amplification, whereas DBS made from all unaffected carriers and UCB showed SMN1 amplification above a well-defined threshold. TREC and RPP30 content in all DBS were within the age-adjusted expected range. CONCLUSIONS: SMA caused by the absence of SMN1 can be detected from the same DBS punch used to screen newborns for SCID.

Limited evolution of human immunodeficiency virus type 1 in the thymus of a perinatally infected child.

BACKGROUND: Involvement of the thymus during human immunodeficiency virus (HIV) infection may impair production of naive lymphocytes leading to more rapid depletion, but the characteristics of primary strains in the thymus are not well studied because of the unavailability of tissue in living individuals. METHODS: We studied the characteristics of HIV type 1 (HIV-1) in a 5-year old perinatally infected child with thymitis and compared the genomic sequences of the HIV-1 C2-V5 region of the env gene in the thymic tissue and peripheral blood. RESULTS: The thymus harbored predominantly viral sequences close to the founder HIV-1 variant that circulated in the blood at 2 and 3 months of age, whereas the peripheral blood virus at 5 years of age had evolved extensively. Viral sequences from circulating CD8(+) T cells at 5 years of age phylogenetically clustered with those from the thymic tissue. CONCLUSIONS: These results indicate the existence of a distinct thymic viral reservoir and suggest that circulating CD8(+) T cells were infected in the thymus, presumably at the CD4(+)CD8(+) thymocyte stage. They also demonstrate that not all thymic HIV infections will necessarily lead to severe thymic dysfunction. The characteristics of the virus strain seeding the thymus may dictate the rate of disease progression.

Sexually transmissible infections and prostate cancer risk.

BACKGROUND: Sexually transmissible infections (STI) have been variably associated with increased risks of prostate cancer, largely in case-control studies. METHODS: In the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we examined risk of prostate cancer in relation to serum antibodies to Chlamydia trachomatis, human papillomavirus-16 and -18, herpes simplex virus-2, cytomegalovirus, and human herpesvirus-8 in 868 cases (765 Whites and 103 Blacks) and 1,283 controls matched by race, age, time since initial screening, and year of blood draw; all blood samples were collected at least 1 year before prostate cancer diagnosis, except for 43 Black cases. We also assessed risk associated with self-reported history of syphilis and gonorrhea. RESULTS: Prevalences of the 7 STIs among controls were weakly correlated, and all were more frequent among Blacks than Whites, except for human herpesvirus-8. Among Whites, prostate cancer risk was not significantly associated with the individual infections or with their number (P(trend) = 0.1); however, men with one or more STI had slightly higher risk (odds ratio, 1.3; 95% confidence interval, 1.0-1.6). Among Blacks, excess risk was associated with IgA antibody to C. trachomatis (odds ratio, 2.1; 95% confidence interval, 1.2-3.6). CONCLUSION: This large prospective study of prostate cancer shows no consistent association with specific STIs and a borderline association with any versus none. Whether a shared response or correlated infection not directly measured underlies the weak association requires further study.

Risk factors for incident herpes simplex type 2 virus infection among women attending a sexually transmitted disease clinic.

OBJECTIVES: To estimate the incidence of herpes simplex type 2 virus (HSV-2) infection, to identify risk factors for its acquisition, and to assess the protective effect of condoms. STUDY DESIGN: Prospective study of 293 HSV-2 seronegative women, aged 18 to 35 years, attending a sexually transmitted disease clinic in Alabama from 1992 to 1995. RESULTS: Incidence of HSV-2 infection was 20.5 per 100 woman-years [95% confidence interval (CI), 13.1-30.5]. Young women (18-20 years) had a significantly higher risk of incident HSV-2 infection [adjusted hazard ratio (HR), 2.8; 95% CI, 1.3-6.4] than older women. Women diagnosed with prevalent or incident bacterial vaginosis had a higher incidence of HSV-2 infection than those who were not so diagnosed (adjusted HR, 2.4; 95% CI, 1.1-5.6). No significant protective effect was observed for consistent (100%) condom use without breakage and slippage against HSV-2 acquisition (adjusted HR, 0.8; 95% CI, 0.2-2.3). CONCLUSION: Acquisition of HSV-2 infection among study participants was higher than previous estimates for adult female sexually transmitted disease clinic attendees, and no protective effect for condoms was demonstrated. The high incidence of HSV-2 infection with its potential for adverse health consequences emphasizes the need for better prevention strategies.

Rapid human immunodeficiency virus testing in labor and delivery: a comparison of implementation models between 2 hospitals.

Despite the use of antiretroviral medications during the antenatal/perinatal period, 280 to 370 human immunodeficiency virus (HIV)-infected infants are born each year in the United States. Women who might transmit the virus to their infants are (1) those not offered antenatal testing due to perceived low risk; (2) those who are noncompliant with their antiretroviral regimen; (3) those with prophylaxis failures despite good compliance; and (4) those who present late to delivery without prenatal care. The Centers for Disease Control and prevention sponsored MIRIAD (mother-infant rapid intervention at delivery) to study rapid testing of women who present late in pregnancy and/or to labor and delivery with unknown HIV status. MIRIAD was implemented in 18 hospitals in 6 American cities. In Atlanta, GA, the 2 participating hospitals had institutional differences that created different models of implementation. Hospital 1 is large and publicly funded, practicing team nursing and utilizing laboratory-based testing. Hospital 2 is a medium-sized nonprofit, whose primary nursing model allowed for specially trained staff to do point-of-care (POC) testing. Regardless of hospital type, nursing care paradigms, or testing model, facilities interested in successfully implementing a similar protocol must formulate policies for testing, notification, and treatment as well as consider dedicating a staff member to the program.

Seroprevalence of herpes simplex virus type 1 in children in the United States.

OBJECTIVES: To describe HSV-1 seroprevalence in children in the United States and to examine factors associated with herpes simplex virus type 1 (HSV-1) infection in children. STUDY DESIGN: Sera samples available from 2989 children age 6 to 13 years who participated in the National Health and Nutrition Examination Surveys (NHANES) 1999-2002 were tested for HSV-1 antibodies using a type-specific immunodot assay. HSV-1 seroprevalence in children age 12 to 13 years was compared with that reported in an earlier survey (NHANES 1988-1994). RESULTS: Overall, HSV-1 seroprevalence in children age 6 to 13 years was 31.1% (95% confidence interval [CI], 28.6% to 33.9%). Seroprevalence increased with age, from 26.3% in 6- to 7-year-olds to 36.1% in 12-to 13-year-olds, and varied by race/ethnicity, birthplace, and poverty level. Among US-born children age 12 to 13 years, the point estimate of HSV-1 seroprevalence was lower in NHANES 1999-2002 than in NHANES 1988-1994 (34.3% vs 38.1%), but the differences were not statistically significant. CONCLUSIONS: HSV-1 is a common infection in US children, with more than 25% infected by age 7. Race/ethnicity, birthplace, and poverty level are predictors for HSV-1 infection in children.

Mother-to-child transmission of HIV-1: timing and implications for prevention.

This article provides a synthesis of clinical trial data with an aim to deduce the timing of mother-to-child transmission of HIV-1. Because transmission of the infection to the infant through breastfeeding is one of the main challenges in fighting paediatric HIV/AIDS in the developing world, we present separate estimates for the timing of HIV transmission for non-breastfeeding and breastfeeding populations. Our estimates predict that, for non-breastfeeding populations, 50% of HIV infections are transmitted to the infant at the very end of pregnancy, near to the time of labour. For breastfeeding populations, the postnatal period accounts for most of the HIV infections transmitted to the infant. We discuss the potential benefit of exclusive breastfeeding for the first 6 months of life as a policy to decrease the magnitude of HIV transmission. Furthermore, we present the hypothesis, based on recent research findings of viral latency, that the time when a fetus initially encounters the virus might not be when infection is established. We discuss the implications of this hypothesis and how it could lead to new interventions for the prevention of mother-to-child HIV transmission.

Trends in herpes simplex virus type 1 and type 2 seroprevalence in the United States.

CONTEXT: Herpes simplex virus type 1 (HSV-1) and type 2 are common infections worldwide. Herpes simplex virus type 2 (HSV-2) is the cause of most genital herpes and is almost always sexually transmitted. In contrast, HSV-1 is usually transmitted during childhood via nonsexual contacts. Preexisting HSV-1 antibodies can alleviate clinical manifestations of subsequently acquired HSV-2. Furthermore, HSV-1 has become an important cause of genital herpes in some developed countries. OBJECTIVE: To examine trends in HSV-1 and HSV-2 seroprevalence in the United States in 1999-2004 compared with 1988-1994. DESIGN, SETTINGS, AND PARTICIPANTS: Cross-sectional, nationally representative surveys (US National Health and Nutrition Examination Surveys [NHANES]), were used to compare national seroprevalence estimates from 1999-2004 with those from 1988-1994, and changes in HSV-1 and HSV-2 seroprevalence since 1976-1980 were reviewed. Persons aged 14 to 49 years were included in these analyses. MAIN OUTCOME MEASURES: Seroprevalence of HSV-1 and HSV-2 antibodies based on results from type-specific immunodot assays; diagnosis of genital herpes. RESULTS: The overall age-adjusted HSV-2 seroprevalence was 17.0% (95% confidence interval [CI], 15.8%-18.3%) in 1999-2004 and 21.0% (95% CI, 19.1%-23.1%) in 1988-1994, a relative decrease of 19.0% between the 2 surveys (95% CI, -28.6% to -9.5%; P<.001). Decreases in HSV-2 seroprevalence were especially concentrated in persons aged 14 to 19 years between 1988 and 2004. In adolescents aged 17 to 19 years and young adults, the decreases in HSV-2 seroprevalence were significant even after adjusting for changes in sexual behaviors. Among those infected with HSV-2, the percentage who reported having been diagnosed with genital herpes was statistically different (14.3% in 1999-2004 and 9.9% in 1988-1994; P = .02). Seroprevalence of HSV-1 decreased from 62.0% (95% CI, 59.6%-64.6%) in 1988-1994 to 57.7% (95% CI, 55.9%-59.5%) in 1999-2004, a relative decrease of 6.9% between the 2 surveys (95% CI, -11.6% to -2.3%; P = .006). Among persons infected with HSV-1 but not with HSV-2, a higher percentage reported having been diagnosed with genital herpes in 1999-2004 compared with 1988-1994 (1.8% vs 0.4%, respectively; P<.001). CONCLUSIONS: These data show declines in HSV-2 seroprevalence, suggesting that the trajectory of increasing HSV-2 seroprevalence in the United States has been reversed. Seroprevalence of HSV-1 decreased but the incidence of genital herpes caused by HSV-1 may be increasing.

Diffusion tensor imaging (DTI) of rodent brains in vivo using a 1.5T clinical MR scanner.

PURPOSE: To evaluate the feasibility of using a clinical 1.5T MR scanner to perform magnetic resonance (MR) diffusion tensor imaging (DTI) on in vivo rodent brains and to trace major rodent neuronal bundles with anatomical correlation. MATERIALS AND METHODS: Two normal adult Sprague Dawley (SD) rats were anesthetized and imaged in a 1.5T MR scanner with a microscopic coil. DTI was performed at a resolution of 0.94 mm x 0.94 mm x 0.5 mm (reconstructed to 0.47 mm x 0.47 mm x 0.5 mm, with b-factors of 600 seconds/mm2 and 1000 seconds/mm2) and a higher resolution of 0.63 mm x 0.63 mm x 0.5 mm (reconstructed to 0.235 mm x 0.235 mm x 0.5 mm, with a b-factor of 1500 seconds/mm2). The fiber-tracking results were correlated with corresponding anatomical sections stained to visualize neuronal fibers. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the neuronal fibers were measured and compared with results in published reports. RESULTS: Several major neuronal fiber tracts, including the corticospinal cord, corpus callosum, and anterior commissure, were identified in all DTI data sets. Stained anatomical sections obtained from the rats confirmed the location of these fibers. The ADC values (0.6-0.8 +/- 10(-3) mm2/second) of the fibers were similar to published figures. However, the FA values (0.3-0.35) were lower than those obtained in previous studies of white matter in rodent spinal cord. CONCLUSION: We have demonstrated the feasibility of using a 1.5T clinical MR scanner for neuronal fiber tracking in rodent brains. The technique will be useful in rodent neuroanatomy studies. Further investigation is encouraged to verify the FA values generated by DTI with such techniques.

Vertebral bone mineral density, marrow perfusion, and fat content in healthy men and men with osteoporosis: dynamic contrast-enhanced MR imaging and MR spectroscopy.

PURPOSE: To prospectively use hydrogen 1 (1H) magnetic resonance (MR) spectroscopy and dynamic contrast material-enhanced MR imaging to measure vertebral body marrow fat content and bone marrow perfusion in older men with varying bone mineral densities as documented with dual x-ray absorptiometry (DXA). MATERIALS AND METHODS: This study had institutional review board approval, and all participants provided informed consent. DXA, 1H MR spectroscopy, and dynamic contrast-enhanced MR imaging of the lumbar spine were performed in 90 men (mean age, 73 years; range, 67-101 years). Vertebral marrow fat content and perfusion (maximum enhancement and enhancement slope) were compared for subject groups with differing bone densities (normal, osteopenic, and osteoporotic). The t test was used for comparisons between groups, and the Pearson test was used to determine correlation between marrow fat content and perfusion indexes. RESULTS: Eight subjects were excluded, yielding a final cohort of 82 subjects (mean age, 73 years; range, 67-101 years) that included 42 subjects with normal bone density (mean T score, 0.8 +/- 1.1 [standard deviation]), 23 subjects with osteopenia (mean T score, -1.6 +/- 0.4), and 17 subjects with osteoporosis (mean T score, -3.2 +/- 0.5). Vertebral marrow fat content was significantly increased in subjects with osteoporosis (mean fat content, 58.23% +/- 7.8) (P = .002) or osteopenia (mean fat content, 55.68% +/- 10.2) (P = .034) compared with that in subjects with normal bone density (50.45% +/- 8.7). Vertebral marrow perfusion indexes were significantly decreased in osteoporotic subjects (mean enhancement slope, 0.78%/sec +/- 0.3) compared with those in osteopenic subjects (mean enhancement slope, 1.15%/sec +/- 0.6) (P = .007) and those in subjects with normal bone density (mean enhancement slope, 1.48%/sec +/- 0.7) (P < .001). CONCLUSION: Subjects with osteoporosis have decreased vertebral marrow perfusion and increased marrow fat compared with these parameters in subjects with osteopenia. Similarly, subjects with osteopenia have decreased vertebral marrow perfusion and increased marrow fat compared with these parameters in subjects with normal bone density.

Osteoporosis is associated with increased marrow fat content and decreased marrow fat unsaturation: a proton MR spectroscopy study.

PURPOSE: To use proton magnetic resonance spectroscopy ((1)H-MRS) to evaluate vertebral marrow fat, and to determine whether bone density correlates with fat content and fat unsaturation levels in postmenopausal women. MATERIALS AND METHODS: Fifty-three women (mean age = 70 years) underwent dual energy x-ray absorptiometry and (1)H-MRS, and 12 young female controls (mean age = 28 years) underwent (1)H-MRS of the lumber spine. Water and lipid peak amplitudes were measured to calculate fat content and fat unsaturation index. Spearman's correlation tests and a t-test comparison of means were applied. RESULTS: (1)H-MRS was successful in 15 normal, 15 osteopenic, and 20 osteoporotic subjects, and in all controls. Marrow fat content was significantly elevated in osteoporotic (65.5% +/- 10%) and osteopenic (63.5% +/- 9.3%) subjects compared to normal subjects (56.3% +/- 11.2%) and young controls (29% +/- 9.6%). The fat unsaturation index was significantly decreased in osteoporotic (0.091 +/- 0.013) and osteopenic (0.097 +/- 0.014) subjects compared to normal subjects (0.114 +/- 0.016) and young controls (0.127 +/- 0.031). A good inverse correlation was observed between the fat content and the unsaturation index (r(s) = -0.53, P < 0.0001). CONCLUSION: Osteoporosis is associated with increased marrow fat. As marrow fat increases, saturated lipids appear to increase preferentially to unsaturated lipids.

Cutting edge: antibody production to pneumococcal polysaccharides requires CD1 molecules and CD8+ T cells.

T cell involvement in Ab responses to thymus-independent type 2 Ags is an immunologic enigma. The identity of these cells and the mechanisms of their TCR engagement to carbohydrate molecules remain unknown. We measured IgG Ab production after immunization with pneumococcal polysaccharides in mice with disruptions in selected genes of the T cell pathway. Nonclassical MHC class I-like CD1 molecules and MHC class I-dependent CD8+ cells were found to be essential. Our findings set forth a new paradigm for humoral responses in which CD1 expression as well as a subset of CD8+ cells are required to provide helper function for Ab production against thymus-independent type 2 polysaccharides, similar to MHC class II-restricted CD4+ cells for protein Ags.

Segmentation of nasopharyngeal carcinoma (NPC) lesions in MR images.

PURPOSE: An accurate and reproducible method to delineate tumor margins from uninvolved tissues is of vital importance in guiding radiation therapy (RT). In nasopharyngeal carcinoma (NPC), tumor margin may be difficult to identify in magnetic resonance (MR) images, making the task of optimizing RT treatment more difficult. Our aim in this study is to develop a semiautomatic image segmentation method for NPC that requires minimal human intervention and is capable of delineating tumor margins with good accuracy and reproducibility. METHODS AND MATERIALS: The segmentation algorithm includes 5 stages: masking, Bayesian probability calculation, smoothing, thresholding and seed growing, and finally dilation and overlaying of results with different thresholds. The algorithm is based on information obtained from the contrast enhancement ratio of T1-weighted images and signal intensity of T2-weighted images. The algorithm is initiated by the selection of a valid anatomical seed point within the tumor by the user. The algorithm was evaluated on MR images from 7 NPC patients and was compared against the radiologist's reference outline. RESULTS: The algorithm was successfully implemented on all 7 subjects. With a threshold of 1, the average percent match is 78.5 +/- 3.86 (standard deviation) %, and the correspondence ratio is 66.5 +/- 7%. DISCUSSION: The segmentation algorithm presented here may be useful for diagnosing NPC and may guide RT treatment planning. Further improvement will be desirable to improve the accuracy and versatility of the method.

Helicobacter pylori prevalence among indigenous peoples of South America.

The seroprevalence of Helicobacter pylori among secluded Indian populations of South America was determined to gain insight into the evolutionary history and possible transmission patterns of the organism. Serum samples obtained from 1024 donors in 22 different villages were tested by enzyme-linked immunosorbent assay for immunoglobulin G antibodies, and the results were confirmed by Western blot. The overall seroprevalence was 92%: >80% of children tested positive by 3 years of age, the highest prevalence in populations studied to date. Comparison of H. pylori prevalence with that of herpes simplex virus type 1, which is known to be transmitted orally, demonstrated a linear correlation in their prevalence rates, suggesting that these pathogens share risk factors. However, H. pylori seroprevalence was consistently higher, indicating that additional routes of transmission exist and/or that the organism is more transmissible. Seroprevalence did not correlate with the length of contact with the outside world. These results suggest that H. pylori was indigenous to the South American Indians and was not introduced by contact with outsiders.