CT scanning is a relatively high-dose procedure. In spite of the use of magnetic resonance imaging, with faster CT scanners and helical techniques CT is becoming more common. There are few data from practice in the United States regarding the age and sex distribution of patients receiving CT scans, what type of scan and how many scans they receive, or how much radiation dose CT scans contribute. We reviewed over 33,700 consecutive CT examinations done at our institution in 1998 and 1999. Information on the types of scans as well as the age and sex distribution of the patients was determined. Between 1990 and 1999, CT examinations in our institution increased from 6.1% to 11.1% of all radiology procedures. Nineteen per cent of all patients seen in our department in the last year had at least one CT scan and more than half had multiple scans on the same day. Thirty-six per cent of all patients had a prior CT examination done on an earlier date. The male/female ratio of patients was 56/44. Studies of children age 0-15 years comprised 11.2% of scans. The highest percentage of scans was done in the 36-50-year-old age group. CT scanning accounted for 67% of the effective dose from diagnostic radiology. In most large hospitals in the United States CT scanning probably accounts for more than 10% of diagnostic radiology examinations and about two-thirds of the radiation dose. Most patients have multiple scan sequences. Studies done on children are probably more common than previously thought.

Age is a minor determinant of mammographic sensitivity in women aged 40 years or older. Sensitivity is substantially decreased with the combination of higher breast density and estrogen replacement therapy use. There was not a notable shift in cancer outcomes in the groups with lower mammographic sensitivity. These data do not support different screening recommendations in women aged 40-49 years or in estrogen replacement therapy users.

Aortic root disease and valve disease are common in patients with AKS, are unrelated to clinical features of AKS, can resolve or progress over time and are associated with clinically important cardiovascular morbidity.

Detection of thyroid nodules by physical examination and high-resolution ultrasonography was compared using small groups of blinded, experienced physician examiners working with a sample of 2441 persons from Estonia, most of whom were Chernobyl nuclear reactor clean-up workers. A random subsample of 113 (5%) persons was subjected to triple control examinations with both physical examination and high-resolution ultrasonography. Positive high-resolution ultrasonographic findings were considerably more reproducible among different observers than were positive physical examination findings. Agreement between methods was poor. Nodules were found in 169 (6.9%) subjects by physical examination and in 249 (10.2%) subjects by high-resolution ultrasonography. Physical examination found only 53 (21%) of the 249 nodules found by high-resolution ultrasonography. High-resolution ultrasonography did not confirm the existence of 115 (68%) of the 169 nodules found by physical examination. Only 6.4% of nodules less than 0.5 cm in diameter, as based on high-resolution ultrasonographic results, were detected by physical examination. Physical examination detection improved with increasing nodule size but was still only 48.2% for nodules larger than 2 cm. Physical examination was relatively effective in detecting nodules in the isthmus of the thyroid gland but much less so for nodules in the upper pole of the gland. Clinical evaluation and epidemiologic studies of nodular thyroid disease stand to benefit from the greater sensitivity and specificity of ultrasonographic examinations.

No abstract