Variability in Radiation Dose From Repeat Identical CT Examinations: Longitudinal Analysis of 2851 Patients Undergoing 12,635 Thoracoabdominal CT Scans in an Academic Health System.

OBJECTIVE: The purpose of this study was to conduct longitudinal analyses of radiation dose data from adult patients undergoing clinically indicated, repeat identical thoracoabdominal CT examinations. MATERIALS AND METHODS: Radiation dose data were electronically collected from 2851 subjects undergoing 12,635 repeat identical CT scans (mean number of scans per patient, 4.8; range, 2-33) in one health system. Included CT protocols were chest-abdomen-pelvis with contrast administration (n = 4621 CT studies of 1064 patients), abdomen-pelvis with contrast administration (n = 876 CT studies of 261 patients), renal stone (n = 1053 CT studies of 380 patients), and chest (n = 6085 CT studies of 1146 patients) without contrast administration. A radiation-tracking software infrastructure was adopted to extract data from DICOM headers in PACS. Size-specific dose estimate (SSDE) was calculated. RESULTS: A trend was observed toward global reduction in SSDE values with all protocols investigated (chest-abdomen-pelvis slope, -1.78; abdomen-pelvis slope, -0.82; renal stone slope, -0.83; chest slope, -0.47; p < 0.001 for all comparisons). The intraindividual analyses of radiation dose distribution showed widespread variability in SSDE values across the four protocols investigated (chest-abdomen-pelvis mean coefficient of variance, 14.02 mGy; abdomen-pelvis mean coefficient of variance, 10.26 mGy; renal stone mean coefficient of variance, 34.18 mGy; chest mean coefficient of variance, 6.74 mGy). CONCLUSION: Although there is a trend toward global reduction in radiation doses, this study showed widespread variability in the radiation dose that each patient undergoing identical repeat thoracoabdominal CT protocols absorbs. These data may provide a foundation for the future development of best-practice guidelines for patient-specific radiation dose monitoring.

High resolution ultra high field magnetic resonance imaging of glioma microvascularity and hypoxia using ultra-small particles of iron oxide.

OBJECTIVES: This study assessed whether ultra-small particles of iron oxide (USPIO) intravascular contrast agent could enhance visualization of tumor microvascularity in F98 glioma bearing rats by means of ultra high field (UHF) high-resolution gradient echo (GRE) magnetic resonance imaging (MRI). In an effort to explain differences in visualization of microvascularity before and after USPIO administration, hypoxia and vessel diameters were assessed on corresponding histopathologic sections. MATERIALS AND METHODS: F98 glioma cells were implanted stereotactically into the brains of syngeneic Fischer rats. Based on clinical criteria, rats were imaged 1 to 2 days before their death with and without USPIO contrast on an 8 Tesla MRI. To identify hypoxic regions of the brain tumor by immunohistochemical staining, a subset of animals also received a nitroimidazole-based hypoxia marker, EF5, before euthanasia. These sections then were compared with noncontrast enhanced MR images. The relative caliber of tumor microvasculature, compared with that of normal brain, was analyzed in a third group of animals. RESULTS: After USPIO administration, UHF high-resolution GRE MRI consistently predicted increased microvascular density relative to normal gray matter when correlated with histopathology. The in-plane visibility of glioma microvascularity in 22 rats increased by an average of 115% and signal intensity within the tumor decreased by 13% relative to normal brain. Tumor microvascularity identified on noncontrast MR images matched hypoxic regions identified by immunohistochemical staining with a sensitivity of 83% and specificity of 89%. UHF GRE MRI was able to resolve microvessels less than 20 micro in diameter, although differences in tumor vessel size did not consistently account for differences in visualization of microvascularity. CONCLUSIONS: USPIO administration significantly enhanced visualization of tumor microvascularity on gradient echo 8 T MRI and significantly improved visualization of tumor microvascularity. Microvascularity identified on precontrast images is suspected to be partly associated with hypoxia.

Formal psychological testing in patients with paradoxical vocal fold dysfunction.

OBJECTIVE: The etiology of paradoxical vocal fold dysfunction (PVFD) has been unclear, but it has long been hypothesized that there is a significant psychological component. The purpose of this study was to elucidate the psychological profiles of patients newly diagnosed with PVFD using psychometrically-sound psychological assessment instruments. STUDY DESIGN: Prospective cohort study of 45 adults newly diagnosed with PVFD at a tertiary university referral center. METHODS: The Minnesota Multiphasic Personality Inventory (MMPI-2) was administered to test for psychopathology. The Life Experiences Survey (LES) was administered to investigate levels of stress. Demographic, medical, and social histories were reviewed. MMPI-2 and LES scores for the PVFD cohort were compared with scores previously established for normative populations. RESULTS: The study population included 81% female and 60% who were age 50 or older. Compared to the normative population for the MMPI-2, significant differences were noted for both male and female PVFD patients; on average, scores were highly elevated on the hypochondriasis scale and hysteria scale and less elevated on the depression scale. This pattern was consistent with conversion disorder (P < .01). In MMPI-2 subset analysis, 18 patients had a classic conversion profile while 13 others had elevated scores in the three scales of interest, but not in the classic conversion disorder pattern. Also, 11 patients had normal scores, suggesting no psychopathology. PVFD patients with a psychological history scored significantly higher on the depression and anxiety scales than PVFD patients without a psychological history. Patients with a history of asthma or gastroesophageal reflux disease (GERD) achieved significantly higher scores on the hypochondriasis scale than those without that medical history. On the LES assessment, female PVFD patients had significantly lower levels of positive stress and higher levels of negative stress than the general population; total levels of stress were not significantly different, however. Male PVFD patients had significantly lower levels of positive, negative, and total stress. For the entire cohort, asthma (65%), GERD (51%), and a history of abuse (38%) were common comorbidities. CONCLUSIONS: On average, in both male and female adults, PVFD is associated with conversion disorder, representing a physical manifestation of underlying psychological difficulty. There also appears to be a subset of PVFD that is not associated with psychopathology. PVFD patients with a previous psychological history are prone to more depressive and anxious symptomatology. Patients with PVFD and a history of asthma or GERD are more likely to excessively complain about physical symptoms. Overall levels of stress are not higher in PVFD patients compared to a general population. However, females report more negative stress, and both males and females may have trouble coping with the amount of stress that they do have. PVFD is more common among women, more prevalent among older individuals, and can be comorbid with asthma, GERD, and previous abuse. These results have implications for treatment- psychotherapy directed for somatoform and conversion disorders may be added to traditional speech therapy for increased efficacy.