Contrast opacification using a reduced volume of iodinated contrast material and low peak kilovoltage in pulmonary CT angiography: Objective and subjective evaluation.

OBJECTIVE The purpose of our study was to evaluate whether a reduced volume of iodinated contrast material for pulmonary CT angiography (CTA) using a low peak kilovoltage (kVp) technique yields equivalent opacification in all vessels. MATERIALS AND METHODS Four hundred fifty-two consecutive pulmonary CTA patients (265 women and 187 men; age range, 18-91 years; mean age, 56.2 years) were retrospectively evaluated. Patients were grouped into those receiving 125 mL (n = 229) and 75 mL (n = 223) of 370 mg I/mL iodinated contrast material. Low kVp was used in all patients. Hounsfield units were measured at lobar, posterobasal segment, posterobasal ramus, and medial basal subsegmental ramus in the left lower lobe. Three thoracic radiologists blinded to contrast dose independently and randomly evaluated the quality of enhancement using a 3-point scale at the same levels. The two-sample Student's t test was used to compare contrast opacification between groups; Spearman's correlation and the C-statistic were used to assess objective and subjective measurements. Interreader agreement was measured using Kendall's coefficient. RESULTS Mean contrast opacification differences between 125 mL versus 75 mL were not statistically significant (p > 0.21) at the lobar, segmental, and posterior basal rami, although the mean trended (p = 0.07) toward higher opacification of the medial basal ramus among 75 mL patients. Across all four pulmonary artery segments, there was good concordance between subjective and objective measurements, significantly higher than the null value of 0.50 (p > 0.05). For subsegmental arteries, concordance between objective and subjective measures was greater for the 75 mL group (p < 0.05). There was good interreader concordance, with a concordance coefficient of 0.70 (95% CI, 0.66-0.74). CONCLUSION Both objective and subjective measures of contrast opacification support a reduction from 125 to 75 mL of contrast medium required for pulmonary CTA.

[1]  Ulf Nyman,et al.  Eighty-peak kilovoltage 16-channel multidetector computed tomography and reduced contrast-medium doses tailored to body weight to diagnose pulmonary embolism in azotaemic patients , 2006, European Radiology.

[2]  C. Heyer,et al.  Image quality and radiation exposure at pulmonary CT angiography with 100- or 120-kVp protocol: prospective randomized study. , 2007, Radiology.

[3]  J. Remy,et al.  Central pulmonary thromboembolism: diagnosis with spiral volumetric CT with the single-breath-hold technique--comparison with pulmonary angiography. , 1992, Radiology.

[4]  A Vieillard-Baron,et al.  Pulmonary embolism detection: prospective evaluation of dual-section helical CT versus selective pulmonary arteriography in 157 patients. , 2000, Radiology.

[5]  Smita Patel,et al.  Pulmonary embolism: optimization of small pulmonary artery visualization at multi-detector row CT. , 2003, Radiology.

[6]  K. Bae,et al.  Peak contrast enhancement in CT and MR angiography: when does it occur and why? Pharmacokinetic study in a porcine model. , 2003, Radiology.

[7]  F. Jacobson,et al.  Vascular enhancement and image quality of MDCT pulmonary angiography in 400 cases: comparison of standard and low kilovoltage settings. , 2009, AJR. American journal of roentgenology.

[8]  Himanshu Shah,et al.  Suspected acute pulmonary embolism: evaluation with multi-detector row CT versus digital subtraction pulmonary arteriography. , 2004, Radiology.

[9]  E. Monga,et al.  Pulmonary embolism: prospective comparison of iso-osmolar and low-osmolarity nonionic contrast agents for contrast enhancement at CT angiography. , 2005, Radiology.

[10]  Peter Vock,et al.  Patient Exposure and Image Quality of Low-Dose Pulmonary Computed Tomography Angiography: Comparison of 100- and 80-kVp Protocols , 2008, Investigative radiology.

[11]  Martine Remy-Jardin,et al.  Management of suspected acute pulmonary embolism in the era of CT angiography: a statement from the Fleischner Society. , 2007, Radiology.

[12]  Pamela K Woodard,et al.  Contrast enhancement in cardiovascular MDCT: effect of body weight, height, body surface area, body mass index, and obesity. , 2008, AJR. American journal of roentgenology.

[13]  J. Goo,et al.  Determination of optimal timing window for pulmonary artery MDCT angiography. , 2007, AJR. American journal of roentgenology.

[14]  Charles F Hildebolt,et al.  Effect of patient weight and scanning duration on contrast enhancement during pulmonary multidetector CT angiography. , 2007, Radiology.

[15]  K. Bae,et al.  Scan and contrast administration principles of MDCT , 2005, European radiology.

[16]  Gustaf E. Lindskog,et al.  Segmental Anatomy of the Lungs , 1955, The Yale Journal of Biology and Medicine.

[17]  Mathias Prokop,et al.  CT angiography of pulmonary arteries to detect pulmonary embolism: improvement of vascular enhancement with low kilovoltage settings. , 2006, Radiology.

[18]  K. Zou,et al.  Clinical validity of a negative computed tomography scan in patients with suspected pulmonary embolism: a systematic review , 2005 .

[19]  Corey A. Kemper,et al.  Cardiothoracic CT angiography: current contrast medium delivery strategies. , 2011, AJR. American journal of roentgenology.

[20]  C. Wittram,et al.  The indeterminate CT pulmonary angiogram: imaging characteristics and patient clinical outcome. , 2005, Radiology.

[21]  K. Garg.  CT of pulmonary thromboembolic disease. , 2002, Radiologic clinics of North America.

[22]  S. Schaller,et al.  Aorto-iliac multidetector-row CT angiography with low kV settings: improved vessel enhancement and simultaneous reduction of radiation dose , 2005, European Radiology.

[23]  A. Baron,et al.  Thromboembolic disease: variability of interobserver agreement in the interpretation of CT venography with CT pulmonary angiography. , 2001, AJR. American journal of roentgenology.

[24]  C. Jackson,et al.  Correlated Applied Anatomy of the Bronchial Tree and Lungs With a System of Nomenclature , 1943 .

[25]  N L Müller,et al.  Clinically suspected pulmonary embolism: utility of spiral CT. , 1999, Radiology.

[26]  B Ghaye,et al.  Peripheral pulmonary arteries: how far in the lung does multi-detector row spiral CT allow analysis? , 2001, Radiology.

[27]  Takeshi Nakaura,et al.  Abdominal dynamic CT in patients with renal dysfunction: contrast agent dose reduction with low tube voltage and high tube current-time product settings at 256-detector row CT. , 2011, Radiology.

[28]  K. Garg,et al.  Clinical validity of helical CT being interpreted as negative for pulmonary embolism: implications for patient treatment. , 1999, AJR. American journal of roentgenology.