59RECENT TECHNICAL ADVANCES

DAVID SUTTON

DAVID SUTTON PICTURES

DR. Muhammad Bin Zulfiqar PGR-FCPS III SIMS/SHL

• Fig. 59.1 Siemens Symphony 1.5 tesla MR system typical of the patient friendly features, incorporating short magnet bore length and flared patient aperture. (Courtesy of Siemens Medical Solutions.)

• Fig. 59.2 An interventional MR suite incorporating a high-field superconducting magnet and a digital X-ray fluoroscopy facility. Patient transfer between the MR system and the X-ray fluoroscopy unit is possible while still within the general environment of an operating theatre. Patient coordinates relative to the two imaging modalities can be maintained via a patient couch transport system. (Courtesy of Philips Medical Systems.)

• Fig. 59.3 (A) T2 - weighted FSE and (B) time-of-flight angiography of a cerebral arteriovenous malformation acquired at 3 Tesla. (Courtesy of Malcolm Randall, VA Medical Center, University of Florida.)

• Fig. 59.4 The effects of improved gradient performance on duration of gradient pulses. Increased gradient rise times result in a reduction in the total pulse length within a sequence for the same useful pulse length.

• Fig. 59.5 Principle of phased array coil technology. Multiple coil arrays provide the benefits of large fields of view along with the signal-to-noise properties of small single-coil elements when signals are combined in an array combination.

• Fig. 59.6 Example of the application of SENSE to abdominal breath-hold imaging for an elderly patient unable to sustain a long breath-hold. (A) 23 s without SENSE; (B) 12 s with SENSE. (Courtesy of Philips Medical Systems.)

• Fig. 59.7 (A,B) Rapid T or small bowel. 2 -TSE imaging using SENSE illustrating the imaging of a fetus inutero. The fast imaging in less than 20 s minimises any possible artefacts from fetal movement with high signal-to-noise and high spatial resolution. (Courtesy of Philips Medical Systems.)

• Fig. 59.8 Schematic diagram for a single shot FSE/TSE sequence. An echo train length of 128 180 pulses, following a single 90 excitation pulse, fills half of k-space. The effective echo time TE ett corresponds to those data lines written to the centre of k-space. The significant number of very long TE ethos give a heavily T 2 -weighted contrast.

• Fig. 59.9 Single-shot breath-hold MRCP examination. Heavily T2-weighted FSE/TSE images demonstrate high contrast fluid signal from pancreatic and biliary system.

• Fig. 59.10 (A) Rapid whole-body screening using a moving table facility. Four sets of coronal images with both T, and T2 weighting are acquired to cover the entire length of the body. (B) Additional transverse images are also acquired at chosen anatomical positions. In total, 750 images are produced in 5 min. Note the high resolution with demonstration of a contained prostatic carcinoma (low signal, arrow) in the left peripheral zone. (Courtesy of Philips Medical Systems.)

• Fig. 59.10 (A) Rapid whole-body screening using a moving table facility. Four sets of coronal images with both T, and T2 weighting are acquired to cover the entire length of the body. (B) Additional transverse images are also acquired at chosen anatomical positions. In total, 750 images are produced in 5 min. Note the high resolution with demonstration of a contained prostatic carcinoma (low signal, arrow) in the left peripheral zone. (Courtesy of Philips Medical Systems.)

• Fig. 59.11 Comprehensive stroke examination performed after (a) 6 h and (b) 24 h from an acute stroke. The protocol includes routine brain sequences in addition to diffusion weighted and T2` dynamic perfusion protocols. The whole examination can be carried out in less than 10 min. The early perfusion and diffusion imaging clearly shows areas of infarct not visible in the standard T 2 and FLAIR images until after 24 hours. (Courtesy of Philips Medical Systems.)

• Fig. 59.12 (A,B) Contrast-enhanced abdominal angiography. A maximum intensity projection image from the CE-MRA 3D acquisition performed during a 15 s breath-hold and triggered using real-time image monitoring of the contrast bolus arrival. The centre of k-space is acquired at the start of the sequence, using an elliptical filling strategy to provide optimal signal as the bolus of contrast passes through the vasculature. (Courtesy of Siemens Medical Solutions.)

• Fig. 59.12 (A,B) Contrast-enhanced abdominal angiography. A maximum intensity projection image from the CE-MRA 3D acquisition performed during a 15 s breath-hold and triggered using real-time image monitoring of the contrast bolus arrival. The centre of k-space is acquired at the start of the sequence, using an elliptical filling strategy to provide optimal signal as the bolus of contrast passes through the vasculature. (Courtesy of Siemens Medical Solutions.)

• Fig. 59.13 High-resolution carotid imaging for the visualisation of thrombus. Transverse images through the area of thrombus show excellent correlation with histology.

• Fig. 59.13 High-resolution carotid imaging for the visualisation of thrombus. Transverse images through the area of thrombus show excellent correlation with histology.

• Fig. 59.13 High-resolution carotid imaging for the visualisation of thrombus. Transverse images through the area of thrombus show excellent correlation with histology.

• Fig. 59.14 A comprehensive MR cardiac examination. The one-stop investigation provides diagnostic information on: (A) myocardial motion using saturation tagging techniques to visualise wall movement through the cardiac cycle; (B) myocardium viability using an inversion recovery technique, 10 min postcontrast administration; (C) black blood-prepared FSE anatomical images showing atheromatous plaques (arrows); (D) coronary artery angiography; (E) myocardial perfusion-weighted images acquired immediately after a bolus injection of contrast; (F) tine gradient echo, bright-blood images, for ventricular volume analysis. (Courtesy of GE Medical Systems.)

• Fig. 59.15 Chemical shift imaging in the brain. Multiple voxels are acquired over slices through the brain. Analysis of the spectra provides quantification of the measured metabolites using an overlaid map on a reference anatomical image. Individual spectra can be viewed and interrogated from within the metabolite maps. The spatial distributions of the various metabolites seen can give important clinical information. (Courtesy of GE Medical Systems.)

• Fig. 59.16 Chemical shift imaging of the prostate. Multiple voxels are acquired over the area of the prostate gland and seminal vesicles. The position of the voxels is shown along with the measured spectra for each voxel. Citrate occurs only within tumour, indicating the extent and spread of the malignancy both within and outside the gland.

• Fig. 59.16 Chemical shift imaging of the prostate. Multiple voxels are acquired over the area of the prostate gland and seminal vesicles. The position of the voxels is shown along with the measured spectra for each voxel. Citrate occurs only within tumour, indicating the extent and spread of the malignancy both within and outside the gland.

• Fig. 59.17 Coronal T 1 -weighted image (A) pre-USIOP showing nodes (arrows) and inguinal veins (v) with intermediate signal intensity. In (B) following USIOP administration the lymph nodes demonstrate signal void due to iron oxide uptake. Veins (v) have high-signal intensity. Histology showed normal lymph nodes. (Courtesy of Guerbet.)

• Fig. 59.18 Sagittal T2 GRE (A) pre-USIOP image with a small (6 x 5 mm) inguinal node (arrow) showing a high signal intensity appearance. (B) Post- USIOP image with the node demonstrating in its ventral part a normal low signal, whereas the dorsal part (4 x 3 mm) remains high signal, in keeping with metastasis. Histology confirmed partially normal (n) and partially metastatic (m) node.

• Fig. 59.20 FDG-PET images in two patients with small-volume colorectal metastases, in the liver (A,B) and in the lung (C). (Courtesy of Professor P. J. Ell, Institute of Nuclear Medicine, Middlesex Hospital, London.)

• Fig. 59.19 Following surgery for colorectal cancer CT (A) shows indeterminate soft-tissue thickening (arrow), FDG-PET image (B) shows an intensely active focus at the site of recurrent tumour (arrow). (Courtesy of Professor P. J. Ell, Institute of Nuclear Medicine, Middlesex Hospital, London.)

• Fig. 59.19 Following surgery for colorectal cancer CT (A) shows indeterminate soft-tissue thickening (arrow), FDG-PET image (B) shows an intensely active focus at the site of recurrent tumour (arrow). (Courtesy of Professor P. J. Ell, Institute of Nuclear Medicine, Middlesex Hospital, London.)

• Fig. 59.21 FDG-PET axial (A) and sagittal (B) images in a patient with a small primary carcinoma arising in the vallecula. (Courtesy of Dr P. Julyan, Christie Hospital, Manchester.)

• Fig. 59.22 FDG-PET axial (A) and sagittal (B) images in a patient with small volume nodal metastases in the neck. (Courtesy of Dr P. Julyan, Christie Hospital, Manchester.)

Fig. 59.23 Two modern ultrasound systems, the larger one on the left is a fully configured system; the smaller one on the right on the couch is nevertheless capable of abdominal and small parts examinations, including Doppler studies.

Fig. 59.24 (A) shows a kidney at fundamental tissue imaging frequency; (B) shows the reduction in noise obtained by imaging at harmonic frequencies; and (C) shows further improvement of the image by using dynamic compound imaging.

• Fig. 59.24 (A) shows a kidney at fundamental tissue imaging frequency; (B) shows the reduction in noise obtained by imaging at harmonic frequencies; and (C) shows further improvement of the image by using dynamic compound imaging.

• Fig. 59.25 A 'B flow' image of an internal carotid artery stenosis with the echoes from the moving blood clearly shown in the lumen of the vessel. (Courtesy of GE Ultrasound.)

• Fig. 59.26 3D ultrasound. (A) shows a reconstruction of a fetal face and arm; (B) shows planar reconstructions from the data volume shown at the bottom right. (Courtesy of Acuson.)

• Fig. 59.27 Extended field of view image of an iliopsoas bursa.

• Fig. 59.28 Diagram of a 2D transducer showing the improvement in beam formation and the associated improvement in spatial and contrast resolution. ( Courtesy of GE ultrasound).

• Fig. 59.29 Intravascular ultrasound images of coronary artery dissections: Left panel: An extensive medial dissection is shown extending from 6 o'clock to 1 o'clock associated with balloon angioplasty. Right panel: A deep submedial dissection is shown between 7 o'clock and 11 o'clock after balloon angioplasty subsequently associated with acute coronary occlusion successfully treated by intracoronary stenting. (Courtesy of Dr N. Uren, Royal Infirmary, Edinburgh.)

• Fig. 59.30 (A) shows a liver tumour on real-time imaging; (B) shows low MI imaging of the vascular phase; (C) shows the same lesion with high MI imaging producing bubble destruction and stimulated acoustic emission. (Courtesy of Dr P. Sidhu, Kings College Hospital.)

• Fig. 59.30 (A) shows a liver tumour on real-time imaging; (B) shows low MI imaging of the vascular phase; (C) shows the same lesion with high MI imaging producing bubble destruction and stimulated acoustic emission. (Courtesy of Dr P. Sidhu, Kings College Hospital.)

• Fig. 59.31 (A) shows two focal areas of relatively reduced echoicity in a fatty liver; (B) shows filling in of these areas after the administration of an echo-enhancing agent with a liver-specific phase, confirming the presence of normal liver tissue in these areas consistent with focal fatty sparing in a fatty liver. (Courtesy of Professor D. 0. Cosgrove, Hammersmith Hospital.)

• Fig. 59.32 (A) Sagittal view of entire spine in trauma patient. Single acquisition with 2.5 mm slices throughout; (B) local axial view through cervical fracture.

• Fig. 59.33 (A) Routine multislice abdominal study with intravenous and oral contrast in patient with cystic renal abnormality; (B) showing quality of coronal reconstruction through kidneys; (C) renal arteries (three) clearly visible.

• Fig. 59.33 (A) Routine multislice abdominal study with intravenous and oral contrast in patient with cystic renal abnormality; (B) showing quality of coronal reconstruction through kidneys; (C) renal arteries (three) clearly visible.

• Fig. 59.34 (A) Axial 0.5 mm acquisition through petrous temporal bone with overlapping reconstructions; (B) coronal reconstructions from axial dataset have similar resolution to source images (isotropic resolution).

• Fig. 59.35 (A) 3D image of air-insufflated colon; (B) endoluminal view of colon ('virtual colonoscopy') demonstrates a rounded submucosal lesion seen at conventional colonoscopy; inset image, oblique axial reformat profiles the lesion and demonstrates fat density within it, confirming a colonic lipoma.

• Fig. 59.36 Volume-rendered image of thoracoabdominal aortic aneurysm.

• Fig. 59.37 Volume-rendered image of abdomen combined with cut surface reformations to demonstrate viscera.

• Fig. 59.38 Coronary calcification scoring. Calcification is highlighted in each vessel (here in left anterior descending) and a cumulative score obtained.

• Fig. 59.39 3D segmented CT angiogram image of renal transplant artery with arterial stent.