title: Modified Subtraction Coronary CT Angiography Method for Patients Unable to Perform Long Breath-Holds: A Preliminary Study.
abstract: Severe calcifications of the coronary arteries are still a major challenge in coronary computed tomography (CT) angiography (CCTA). Subtraction CCTA using a 320-detector row CT scanner has recently been introduced for patients with severe calcifications. However, the conventional subtraction CCTA method requires a long breath-holding time of approximately 20-40 seconds. This is a major problem in clinical practice because many patients may not be able to perform such a long breath-hold. We explored a modified subtraction CCTA method with a short breath-holding time to overcome this problem.
  
  
  
  This study was approved by our institutional review board, and all patients gave written informed consent. A total of 12 patients with a coronary calcium score of >400 were enrolled in this study. All patients were unable to hold their breath for more than 20 seconds. Modified subtraction CCTA was performed using the bolus-tracking method. The acquisition protocol was adjusted so that the mask scan was acquired 10 seconds after the postcontrast scan during a single breath-hold. The subtraction image was obtained by subtracting the mask image data from the postcontrast image data. The breath-holding times were recorded. Enhancement of the coronary arteries in the subtraction images was assessed. Subjective image quality was evaluated in a total of 32 segments using a 4-point scale.
  
  
  
  The mean breath-holding time was 12.8 ± 0.8 seconds (range, 12-14 seconds). The average CT number in the coronary arteries was 288.6 ± 80.5 Hounsfield units (HU) in the subtraction images. Average image quality was significantly increased from 2.1 ± 0.9 with conventional CCTA to 3.1 ± 0.7 with subtraction CCTA (P < 0.001). With subtraction CCTA, the number of non-diagnostic segments was significantly reduced from 53% to 19% (P = 0.001).
  
  
  
  This preliminary study has shown that our modified subtraction CCTA method allows the breath-holding time to be shortened to <15 seconds. This may substantially improve the success rate of subtraction CCTA by reducing artifacts and allowing this technique to be applied to patients who are unable to perform a long breath-hold.
authors.affiliation: Division of Cardiovascular Radiology, Department of Radiology, Iwate Medical University, 19-1 Uchimaru, Morioka 020-8505, Japan. Electronic address: kyoshi@iwate-med.ac.jp.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yoshioka
authors.affiliation: Division of Cardiovascular Radiology, Department of Radiology, Iwate Medical University, 19-1 Uchimaru, Morioka 020-8505, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Tanaka
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Kyouhei
authors.initials: K
authors.lastname: Nagata
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sasaki
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Kouta
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Ueda
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sugawara
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Ueyama
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Chiba
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Akinobu
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: Center for Radiological Science, Iwate Medical University Hospital, Morioka, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D000368:Aged; D016477:Artifacts; D062485:Breath Holding; D000072226:Computed Tomography Angiography / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013382:Subtraction Technique
keywords: Computed tomography; coronary CT angiography; coronary artery calcification; subtraction