Reproducibility of intravoxel incoherent motion of liver on a 3.0T scanner : free-breathing and respiratory-triggered sequences acquired with different numbers of excitations

Purpose: To optimise the intravoxel incoherent motion (IVIM) imaging of the liver on a 3.0T scanner by assessing parameter reproducibility on free-breathing (FB) and respiratory-triggered (RT) sequences acquired with different numbers of signal averages (NSA). Material and methods: In this prospective study 20 subjects (M/F: 10/10; age: 25-62 years, mean: 39 years) underwent IVIM magnetic resonance imaging (MRI) on a 3.0T scanner using an 18-channel phase-arrayed coil and four different echo-planar sequences, each with 10 b values: 0, 10, 30, 50, 75, 100, 150, 200, 500, and 900 s/mm2. Images were acquired with FB and RT with NSA = 1-4 (FBNSA1-4, RTNSA1-4) and with NSA = 3-6 (FBNSA3-6, RTNSA3-6). Subsequently, for the assessment of reproducibility of IVIM-derived parameters (f, D, D*), each subject was scanned again with an identical protocol during the same session. IVIM parameters were calculated. The distribution of IVIM-parameters for each DWI sequence were given as the median value with first and third quartile. Inter-scan reproducibility for each IVIM parameter was evaluated using coefficient of variance and Bland-Altman difference. Differences between FB sequence and RT sequence were tested using non-parametric Wilcoxon signed-rank test. Results: Mean coefficient of variance (%) for f, D, and D* ranged from 60 to 64, from 58 to 84, and from 82 to 99 for FBNSA1-4 sequence; from 50 to 69, from 41 to 97, and from 80 to 82 for RTNSA1-4 sequence; from 22 to 27, 15, and from 70 to 80 for FBNSA3-6 sequence; and from 21 to 32, from 12 to, and from 50 to 80 for RTNSA3-6 sequence, respectively. Conclusions: Increasing the number of signal averages for IVIM acquisitions allows us to improve the reproducibility of IVIM-derived parameters. The sequence acquired during free-breathing with NSA = 3-6 was optimal in terms of reproducibility and acquisition time

The role of computed tomography in the diagnostics of diaphragmatic injury after blunt thoraco-abdominal trauma

BACKGROUND: Diaphragmatic injuries occur in 0.8-8% of patients with blunt trauma. The clinical diagnosis of diaphragmatic rupture is difficult and may be overshadowed by associated injuries. Diaphragmatic rupture does not resolve spontaneously and may cause life-threatening complications. The aim of this study was to present radiological findings in patients with diaphragmatic injury. MATERIAL AND METHODS: The analysis of computed tomography examinations performed between 2007 and 2012 revealed 200 patients after blunt thoraco-abdominal trauma. Diaphragmatic rupture was diagnosed in 13 patients. Twelve of these patients had suffered traumatic injuries and underwent a surgical procedure that confirmed the rupture of the diaphragm. Most of diaphragmatic ruptures were left-sided (10) while only 2 of them were right-sided. In addition to those 12 patients there, another patient was admitted to the emergency department with left-sided abdominal and chest pain. That patient had undergone a blunt thoracoabdominal trauma 5 years earlier and complained of recurring pain. During surgery there was only partial relaxation of the diaphragm, without rupture. The most important signs of the diaphragmatic rupture in computed tomography include: segmental discontinuity of the diaphragm with herniation through the rupture, dependent viscera sign, collar sign and other signs (sinus cut-off sign, hump sign, band sign). RESULTS: In our study blunt diaphragmatic rupture occurred in 6% of cases as confirmed intraoperatively. In all patients, coronal and sagittal reformatted images showed herniation through the diaphragmatic rupture. In left-sided ruptures, herniation was accompanied by segmental discontinuity of the diaphragm and collar sign. In right-sided ruptures, predominance of hump sign and band sign was observed. Other signs were less common. CONCLUSIONS: The knowledge of the CT findings suggesting diaphragmatic rupture improves the detection of injuries in thoraco-abdominal trauma patients