Objective: Whole-body multislice helical computed tomography (MSCT) becomes increasingly important as a diagnostic tool in patients with multiple injuries. We describe time requirement of two different diagnostic approaches to multiple injuries one with whole-body-MSCT (MSCT Trauma-Protocol) as the sole radiologic procedure and one with conventional use of radiography, combined with abdominal ultrasound and organ focused CT (Conventional-Trauma-Protocol).
T staging by enhanced arterial phase (A) and delayed phase multi-slice spiral computed tomography scanning (B). The images show a tumor located in the hepatic flexure of the colon.
T staging and N staging by enhanced arterial phase (A), portal venous phase (B), and delayed phase multi-slice spiral computed tomography scanning (C). The images show a tumor in the hepatic flexure of the colon. The number and size of the lymph nodes are increased around the rectus (arrow).
N staging by enhanced arterial phase (A) and portal venous phase multi-slice spiral computed tomography (B). The images show a clear tumor in the hepatic flexure of the colon and metastatic lymph nodes.
M staging by enhanced arterial phase (A), portal venous phase (B), and delayed phase multi-slice spiral computed tomography scanning (C). The images show multiple hepatic metastases.
Background: Surveillance conventional coronary angiography (CCA) is recommended 2 to 6 months after stent-supported left main coronary artery (LMCA) percutaneous coronary intervention due to the unpredictable occurrence of in-stent restenosis (ISR), with its attendant risks. Multislice computed tomography (MSCT) is a promising technique for noninvasive coronary evaluation. We evaluated the diagnostic performance of high-resolution MSCT to detect ISR after stenting of the LMCA.
Whole body computed tomography has developed at a rapid pace in the past decade, spurred on by the introduction of spiral and multislice scanning. These new technologies have not only improved diagnostic accuracy, but also made new applications possible that were previously accessible only through more complex or invasive techniques.
Since the introduction of multislice computed tomography (MSCT) in 1998, non-invasive cardiac imaging has developed rapidly. In the recent past, two different objectives can be observed in the technological development of cardiac MSCT. On the one hand, the number of detector rows was increased up to 320 in single-source scanners in order to ensure simultaneous coverage of the entire heart with a high spatial resolution. On the other hand, a higher temporal resolution was attained, which was achieved by introducing a dual-source scanner with a maximum of 2x64 rows (2x128 slices). Currently, the maximum temporal resolution is 75ms on a dual-source system and the maximum spatial resolution is 0.5mm on a single-source system. The high spatial resolution of MSCT results in excellent morphological depiction of coronary arteries, bypasses, myocardium and even heart valves, which can be simultaneously reconstructed from a 3D data set. While motion artefacts at heart rates up to 65bpm have generally been reduced, higher heart rates, arrhythmias, severe calcification, coronary stents and an unfavourable signal-to-noise ratio in obese patients remain challenges.
Spiral CT was an important technological advance, but many limitations and compromises remained. The rotational speed of the gantry was generally one rotation per second, and clinical results suggested that a pitch (ratio of longitudinal distance moved by the tabletop during one gantry rotation to beam collimation) greater than two was undesirable. As a result, either large volumes could be covered, or thin sections acquired, but not both. Another CT scanner employed a dual array of two side-by-side detector rows, and represented an early version of multislice technology. 3 However, while this scanner was an improvement over single detector spiral CT in terms of coverage, 4 substantial limitations remained. It was not until 1998 that a scanner with four detector rows became commercially available. Modern multislice CT using four or more detector rows essentially abolishes the remaining obstacles to rapid isotropic volumetric imaging by utilizing multiple side-by-side detectors simultaneously. The most recent scanners use up to 16 detector rows. Such multislice CT systems can collect up to four slices of data in about 350 milliseconds and reconstruct a 512 by 512 matrix image from millions of data points in less than a second. An entire body cavity (brain, chest, or abdomen) can be scanned in 5 to 10 seconds using the most advanced multislice CT systems. Faster imaging with modern scanners is due not only to multiple detector rows, but also to increased gantry rotational speed. Many commercial scanners are now capable of a complete gantry rotation in 0.5 seconds or less.
A potential source of confusion that arises with respect to multislice CT is the definition of pitch. Pitch can be defined in one of two ways: either as the ratio of longitudinal distance moved by the tabletop during one gantry rotation to beam collimation, or the ratio of longitudinal distance moved by the tabletop during one gantry rotation to slice thickness. In single detector spiral CT, these two definitions are the same, since the slice thickness is the beam collimation. In multislice CT, the collimated beam is split into several slices, and therefore the definitions of pitch are different. For example, a four-channel multislice scanner acquiring 2.5-mm-thick slices (beam collimation of 10 mm) at a tabletop speed of 15 mm per 1-second gantry rotation could be defined as having a pitch of 6 (longitudinal distance moved by the table-top during one gantry rotation/slice thickness = 15/2.5 = 6) or 1.5 (longitudinal distance moved by the tabletop during one gantry rotation/beam collimation = 15/10 = 1.5). There is no current consensus on which definition is preferable. While most manufacturers use the ratio of longitudinal distance moved by the table-top during one gantry rotation to slice thickness, there are arguments related to basic science and calculation of radiation dose that suggest the alternative definition is more appropriate. In any event, it is important to clarify which definition of pitch is being utilized when describing CT protocols and parameters for multislice scanners. 59ce067264