Multislice CT scanner

Many users of spiral and multislice CT scanners have switched from conventional image interpretation to primary digital interpretation on the monitor. The interactive options have numerous advantages... 

With conventional MR imaging techniques, lymph nodes are visualized vdien they have a size of at least 1.0-1.5 cm [10]. Optimized imaging techniques (body phased-array coil, 512 matrix, 3D acquisition) or state-of-the-art spiral or multislice CT scanners depict lymph nodes as small at about 3-5 mm [7,8]. These techniques usually allow good evaluation of the lymph nodes adjacent to the straight great vessels (Fig. 15.1). 

MDCT is a well-established method to delineate and stage TCC. With the introduction of multislice CT scanners, single-breath coverage with thin-slice reconstruction of the whole urinary tract is possible (Figs. 32.1, 32.2). The detection rate for upper and lower urinary tract tumors is comparable to RP and cystoscopy, with sensitivity for the upper urinary tract of up to 92%, and similar sensitivity for the lower tract (Park et al. 2007 Fig. 32.3). With a better detection rate and the multifocal nature of TCC, CTU replaces EU for detection of TCC (Albani et al. 2007). In this study, the usefulness of CT for evaluation of patients with hematuria was evaluated. 

CT scanners are now nearly ubiquitous in or near the emergency departments of most North American hospitals. With multislice scanners, a noncontrast CT (NCCT) examination of the brain can be performed in well under 1 minute, with the newest scanners able to scan the head in 10 seconds or less. In most centers, the first (and sometimes only) imaging study undertaken for patients with suspected acute stroke is NCCT. 

Multislice scanners allow flexibility in designing a rapid and efficient CTA protocol for acute ischemic stroke without causing a significant delay in the institution of thrombolytic therapy. At our institution, the acute ischemic stroke protocol consists of (1) unenhanced head CT, (2) one-pass CTA of the head and neck, and (3) CTP of the head at 1-2 nonoverlapping levels with 4-8 cm of brain coverage (with a 64-slice CT scanner). Of note, using the 64-slice CT scanner, the intracranial and extracranial vasculature from arch to vertex can be imaged in one-pass in less than 15 s. 

Depending on the scanner used, both advantages of multislice CT can be combined by finding a compromise between slice thickness and speed. 

After the introduction of multislice CT in 1992 with the advent of dual-slice scanners, this technology was improved in 1998 by the implementation of 4-slice, in 2000 with 8-slice, in 2002 with 16-slice, and in 2004 with 64-slice scanners. Development continues and at the turn of 2006 the first 64-slice dual-source devices with a very high temporal and spatial resolution were installed thus one seems to observe a 2-year cycle for the launch of new CT... 

CT-angiography with the use of a multislice helical scanner, with faster scanning speeds and narrow collimation following dynamic contrast injection on both axial images and multiplanar reformats, allows for high-quality demonstration of the surrounding vasculature. 

Micro-CT typically utilizes cone-beam geometry and is thus true volume CT . The term volume CT or volumetric CT has been used in association with the Mayo Clinic effort to build the dynamic spatial reconstmctor (DSR) (33). The recent development of multislice row (MDCT) scanners represents a significant movement toward the use of true cone-beam geometry. Micro-CT offers a unique opportunity to test the mathematics and image processing needs of clinical scanners. 

In four-slice spiral CT the same acquired raw data set can be used to reconstruct two or more data sets of varying thickness. For this reason, it is important to distinguish between acquisition parameters, given as (NxSC/TF), and reconstruction parameters, expressed as (SW/Rl) (Cademartiri et al. 2003). With multislice scanners, two definitions of pitch factor are used, depending on whether a section (P =TF/SC) or total collimation of the detector array (P=TF/NxSC) is chosen as the reference (Prokop 2003c). 

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