Image quality and radiation dose of pulmonary CT angiography performed using 100 and 120 kVp.

OBJECTIVE: The objective of our study was to compare image quality and radiation dose of pulmonary CT angiography (CTA) performed in the same patient cohort using tube potentials of 100 and 120 kVp. MATERIALS AND METHODS: The study group for this retrospective study was 32 patients (22 women, 10 men) with a mean age of 57 years (age range, 28-83 years; body weight < 100 kg). Patients underwent pulmonary CTA studies performed using 120 and 100 kVp while other scanning parameters were kept constant. Two observers measured image signal and image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and SNR dose and CNR dose. Two additional observers performed qualitative image quality analysis using a 5-point grading scale (5 = excellent). RESULTS: The reduction in tube potential caused image signal to increase by 29% (p < 0.0001), image noise to increase by 68% (p < 0.0001), CNR dose to decrease by 0.8% (p = 0.91) and SNR to decrease by 24% (p = 0.0002) and CNR by 20% (p = 0.0019). Radiation dose (dose-length product) was decreased by 37% to 379.26 mGy × cm at 100 kVp from 604.46 mGy × cm at 120 kVp (p < 0.0001). The median pulmonary arteries image quality scores for observers 1 and 2, respectively, were as follows at 100 kVp: main, 5 and 5; lobar, 5 and 4.5; and segmental, 5 and 4. At 120 kVp, the median image quality scores for observers 1 and 2 were as follows: main, 5 and 5; lobar, 5 and 5; segmental, 4 and 4. A Wilcoxon test analysis indicated no significant difference in image quality between the studies (main, p = 0.59; lobar, p = 0.88; segmental, p = 0.79). CONCLUSION: Pulmonary CTA can be performed using a tube potential of 100 kVp in patients who weigh less than 100 kg (220 lb). Reducing the tube potential from 120 to 100 kVp results in a 37% reduction in radiation dose without a significant impact on diagnostic image quality.

Guide to surgical procedures on hollow viscera: part 1--Esophageal, gastric, and restrictive bariatric procedures.

OBJECTIVE: The objective of this article is to explore with a surgical perspective the key radiologic features after common esophageal, gastric, and bariatric procedures. CONCLUSION: An understanding of procedures on the hollow viscera is essential for radiologists at any level. The ability to quickly recognize postoperative anatomy is critical to accurately and efficiently interpret routine imaging studies and to diagnose postoperative complications.

Guide to surgical procedures on hollow viscera: part 2--Colorectal, ostomy, and malabsorptive bariatric procedures.

OBJECTIVE: The objective of this article is to explore with a surgical perspective the key radiologic features of common bariatric, colorectal, and ostomy procedures. The images and diagrams show relevant postoperative anatomy. CONCLUSION: An understanding of procedures on the hollow viscera is essential for a radiologist at any level. The ability to quickly recognize postoperative anatomy is critical to accurately and efficiently interpret routine imaging studies and to diagnose postoperative complications.

Pictorial essay: the value of rectal water in the assessment of rectosigmoid pathology.

The rectosigmoid region is a common location for the development of both malignant and benign diseases of the large bowel in adults. In many cases, rectal water provides an ideal contrast agent in the evaluation of rectosigmoid pathology. It allows optimal visualization of the mural layers and pericolic fat, as well as superior detection of flat or small sessile mural-based intralumenal filling defects. The authors of this article have devised practical clinical indications for the administration of rectal water that may help guide the radiologist in deciding when to implement this technique. Furthermore, this pictorial essay will describe the technique used by the authors, highlight the utility of this technique, and explore its practical applications and limitations in clinical practice.

Quantitative assessment of the superior sagittal sinus on unenhanced computed tomography.

PURPOSE: To determine the relationship between hemoglobin levels and attenuation measurements of the superior sagittal sinus (SSS) on unenhanced computed tomography (UECT). Secondly, to determine if SSS attenuation values are normally distributed such that measurements below and above certain thresholds are suggestive of pathology, such as anemia or acute venous thrombosis respectively. METHODS: Institutional review board approval was obtained for retrospective review of adult patients having both an UECT head examination and a complete blood count within 24 h of the scan. A cohort of 151 consecutive patients formed the study sample (76 males and 75 females, 17-91 years of age with a mean of 61). The dorsal aspect of the SSS was divided into upper, middle and lower segments. Using freehand and circle region of interest (ROI) techniques, a total of six attenuation measurements were obtained from each patient. Next, statistical analyses were preformed to assess the correlation between Hgb levels and attenuation values, and distribution curves were plotted to assess the normal range of SSS attenuation measurements. RESULTS: There is a moderate, yet statistically significant (p<0.001), correlation between Hgb levels and attenuation values in upper, middle and lower segments of the SSS (r=0.487, 0.497 and 0.533 respectively). Based on the calculated mean, median and mode, the attenuation values are normally distributed. When using the freehand ROI technique, the mean value is 50 Hounsfield Units (HU) with a standard deviation (SD) of 7.5. Attenuation values less than 2 SDs (35 HU) are highly suggestive of anemia (specificity and PPV=100%). CONCLUSION: There is a moderate, yet statistically significant, correlation between Hgb levels and attenuation of the SSS on UECT. Furthermore, attenuation measurements of the SSS are normally distributed with a mean of 50 HU and a SD of 7.5. Therefore, quantitative assessment of the SSS may prove useful in the clinical practice of a radiologist; namely, in the diagnosis of anemia and acute venous thrombosis.

Perivascular spaces: normal and giant.

The purpose of this paper is to discuss both normal perivascular spaces (PVSs) and pathological giant perivascular spaces (GPVSs). The anatomy and physiology of normal PVSs, including important immunological and lymphatic roles, are described. Special attention is given to the Magnetic Resonance Imaging (MRI) findings of both normal and GPVSs. Furthermore, the clinical features and pathogenesis of GPVSs are explored, with special emphasis on the pathological implications of these lesions, and their relevance. It is important that symptomatic GPVSs not be mistaken for more devastating disease processes. When the lesions in question occur in a characteristic location along the path of a penetrating vessel, are isointense with cerebrospinal fluid on all MRI sequences, do not enhance with contrast material, are not calcified, and have normal adjacent brain parenchyma, their appearance is pathognomonic of GPVSs. The clinician should realize that an extensive differential diagnosis is superfluous and that biopsy is unnecessary in these patients. Instead, the clinical focus should be aimed at neurosurgical intervention, as dictated by the symptoms of mass effect.