1286
Magnetic resonance imaging
in
perianal
Crohn’s disease SiR,—Anorectal lesions in Crohn’s disease are common. Exact diagnosis, accurate assessment, and classification of these complications are essential before surgical treatment or before institution of steroid therapy for active disease. Apart from clinical examination, diagnostic methods such as computed tomography or endosonography3,4 are used to detect perianal lesions. Mr Lunniss and colleagues (Aug 15, p 394) report magnetic resonance imaging (MRI) of anal fistulae, and in a pilot study MRI proved a valuable and accurate method in detecting perianal and perirectal abscesses and fistulae in Crohn’s disease. We add our experience of MRI based on a prospective study in 34 patients with established Crohn’s disease and suspected perianal complications.6 Operative findings were the gold standard. Evaluation of the 34 patients was done by independent observers according to a predefined protocol. Clinical and digital examination was done by an experienced surgeon without anaesthesia. Proctoscopy and/or rectoscopy were done during this evaluation whenever possible. The patients were scanned by MRI at 15 T, with a Helmholtz surface coil. Tl-weighted and T2-weighted multislice spin-echo images were obtained, coronal and axial planes were viewed in each patient. All abscesses noted at operation were precisely documented by MRI. 8 deep abscesses (intersphincteric and ischiorectal) unsuspected by clinical examination were demonstrated by MRI. With respect to subcutaneous and anovaginal fistulae, MRI was not more accurate than digital and clinical evaluation, but the relation of branched fistulae (secondary tracts) to the sphincter apparatus and the pelvic floor muscles was more easily established by MRI than by digital examination. Our results show that MRI offers a non-invasive and painless diagnostic method for exact evaluation of anorectal complications in Crohn’s diease. Discrimination of active inflammation and scar tissue is possible by differently weighted MRI analysis. Advantages over endosonography are the absence of pain and the independence of an observer experienced in the method. The main advantage over computed tomography is the possibility of images in two different planes (horizontal and coronary) which greatly facilitates the exact preoperative location of lesions with respect to the sphincter apparatus and the other structures of the pelvic floor. We conclude that MRI is more accurate than clinical examination in detecting perianal abscesses in patients with Crohn’s disease. Departments of Gastroenterology, Surgery, and Diagnostic Radiology, Eberhard Karls University of Tubingen, D-7400 Tubingen, Germany
HARRO JENSS MICHAEL STARLINGER MARTIN SKALEIJ
EJ, Jones B, Bayless TM, Siegelman SS. CT evaluation of Croho’s disease: effect on patient management. AJR 1987; 148: 537-40. 2. Gore RM. Cross-sectional imaging of inflammatory bowel disease. Radiol Clin N Am 1. Fishman EJ, Wolf
1987; 25: 115-31. 3. Tio TL, Mulder CJJ, Wijers OB, Sars PRA, Tytgat GNJ. Endosonography of perianal and pericolorectal fistula and/or abscess in Crohn’s disease. Gastrointestinal Endoscopy 1990; 36: 331-36. 4. Wijers OB, Tio TL, Tytgat GNJ. Ultrasonography and endosonography in the diagnosis and management of inflammatory bowel disease. Endoscopy 1992; 24: 559-64. 5. Koelbel G, Schmiedl U, Majer MC, et al. Diagnosis of fistulae and sinus tracts in patients with Crohn’s disease: value of MR imaging. AJR 1989; 152: 999-1003. 6. Skalej M, Bongers H, Aicher H, Weinlich M, Starlinger M, Jenss H. Value of MR-tomography in perianal Crohn’s disease: a prospective study. Gastroenterology 1992; 102 (suppl): A419.
Computed tomographic angiography for carotid imaging SIR,-Accurate assessment of carotid disease is necessary before endarterectomy. The most accurate preoperative assessment is by carotid angiography, but this invasive procedure carotid
has complications.! The two more recently developed non-invasive techniques for imaging of the carotid arteries, colour doppler ultrasound and magnetic resonance angiography (MRA), have disadvantages such that conventional preoperative carotid angiography continues to be done. Doppler fails to provide the
CTA in
severe
stenosis.
Short segment of subtotal occlusion is visible in carotid artery
surgeon with
proximal left internal
overview of the carotid circulation and may or give a false diagnosis of carotid occlusion.2,3 MRA tends to overestimate the degree and length of stenosis because of signal loss in the stenotic segment. 4,5 We describe a non-invasive computed tomographic angiography (CTA) technique that may overcome some of these limitations. A newly developed slip-ring CT scanner capable of 50 rotations in 50 s is used (Tomoscan SR-HP, Philips Medical Systems). With a table increment of 3 mm/s, maximum of 150 3 rnm slices overlapping 2 mm with each adjacent slice can be acquired in under 1 min. 120 ml intravenous contrast material is administered via an antecubital vein at 1-5 to 2.0 ml/s. The angiographic image is produced on an independent 3-D workstation (Gryoview, Philips Medical Systems) with these CT images (figure). The densely opacified carotid lumen can be recognised automatically by the reconstruction program, so that segmentation and reconstruction takes only 30-45 min. CTA allows the non-invasive production of an angiographic image without the risks and costs of conventional angiography. The sensitivity and specificity of this technique are not yet known, but preliminary results are promising. As CTA is further refined, it may be possible to reduce the need for preoperative carotid an
underdiagnose distal plaques
angiography.
Departments of Diagnostic Radiology and Surgery, University Hospital of Utrecht, 3584 CX Utrecht, Netherlands
EVAN H. DILLON MAARTEN S. VAN LEEUWEN M. ARANCHA FERNANDEZ BERT C. EIKELBOOM WILLEM TH. MALI
1. Earnest F, Forbes
G, Sandok BA, et al. Complications of cerebral angiography prospective assessment of risk. AJR 1984; 142: 247-52. 2. Erickson SJ, Mewissen MW, Foley WD, et al. Stenosis of the internal carotid artery: assessment using color Doppler imaging compared with angiography. AJR 1989; 152: 1299-305. W, Kloetzsch C, Hennerici M. Carotid artery disease assessed by color Doppler flow imaging: correlation with standard Doppler sonography and angiography. AJR 1990; 154: 1061-68. 4. Riles TS, Eidelman EM, Litt AW, Pinto RS, Oldford F, Thoe Schwartzenberg GWS. Comparison of magnetic resonance angiography, conventional angiography, and duplex scanning. Stroke 1992; 23: 341-46. 5. Anderson CM, Saloner D, Lee RE, et al. Assessment of carotid artery stenosis by MR angiography: comparison with X-ray angiography and color-coded Doppler ultrasound. AJNR 1992; 13: 989-1003. 3. Steinke
Magnetic resonance imaging
in
perianal
Crohn’s disease SiR,—Anorectal lesions in Crohn’s disease are common. Exact diagnosis, accurate assessment, and classification of these complications are essential before surgical treatment or before institution of steroid therapy for active disease. Apart from clinical examination, diagnostic methods such as computed tomography or endosonography3,4 are used to detect perianal lesions. Mr Lunniss and colleagues (Aug 15, p 394) report magnetic resonance imaging (MRI) of anal fistulae, and in a pilot study MRI proved a valuable and accurate method in detecting perianal and perirectal abscesses and fistulae in Crohn’s disease. We add our experience of MRI based on a prospective study in 34 patients with established Crohn’s disease and suspected perianal complications.6 Operative findings were the gold standard. Evaluation of the 34 patients was done by independent observers according to a predefined protocol. Clinical and digital examination was done by an experienced surgeon without anaesthesia. Proctoscopy and/or rectoscopy were done during this evaluation whenever possible. The patients were scanned by MRI at 15 T, with a Helmholtz surface coil. Tl-weighted and T2-weighted multislice spin-echo images were obtained, coronal and axial planes were viewed in each patient. All abscesses noted at operation were precisely documented by MRI. 8 deep abscesses (intersphincteric and ischiorectal) unsuspected by clinical examination were demonstrated by MRI. With respect to subcutaneous and anovaginal fistulae, MRI was not more accurate than digital and clinical evaluation, but the relation of branched fistulae (secondary tracts) to the sphincter apparatus and the pelvic floor muscles was more easily established by MRI than by digital examination. Our results show that MRI offers a non-invasive and painless diagnostic method for exact evaluation of anorectal complications in Crohn’s diease. Discrimination of active inflammation and scar tissue is possible by differently weighted MRI analysis. Advantages over endosonography are the absence of pain and the independence of an observer experienced in the method. The main advantage over computed tomography is the possibility of images in two different planes (horizontal and coronary) which greatly facilitates the exact preoperative location of lesions with respect to the sphincter apparatus and the other structures of the pelvic floor. We conclude that MRI is more accurate than clinical examination in detecting perianal abscesses in patients with Crohn’s disease. Departments of Gastroenterology, Surgery, and Diagnostic Radiology, Eberhard Karls University of Tubingen, D-7400 Tubingen, Germany
HARRO JENSS MICHAEL STARLINGER MARTIN SKALEIJ
EJ, Jones B, Bayless TM, Siegelman SS. CT evaluation of Croho’s disease: effect on patient management. AJR 1987; 148: 537-40. 2. Gore RM. Cross-sectional imaging of inflammatory bowel disease. Radiol Clin N Am 1. Fishman EJ, Wolf
1987; 25: 115-31. 3. Tio TL, Mulder CJJ, Wijers OB, Sars PRA, Tytgat GNJ. Endosonography of perianal and pericolorectal fistula and/or abscess in Crohn’s disease. Gastrointestinal Endoscopy 1990; 36: 331-36. 4. Wijers OB, Tio TL, Tytgat GNJ. Ultrasonography and endosonography in the diagnosis and management of inflammatory bowel disease. Endoscopy 1992; 24: 559-64. 5. Koelbel G, Schmiedl U, Majer MC, et al. Diagnosis of fistulae and sinus tracts in patients with Crohn’s disease: value of MR imaging. AJR 1989; 152: 999-1003. 6. Skalej M, Bongers H, Aicher H, Weinlich M, Starlinger M, Jenss H. Value of MR-tomography in perianal Crohn’s disease: a prospective study. Gastroenterology 1992; 102 (suppl): A419.
Computed tomographic angiography for carotid imaging SIR,-Accurate assessment of carotid disease is necessary before endarterectomy. The most accurate preoperative assessment is by carotid angiography, but this invasive procedure carotid
has complications.! The two more recently developed non-invasive techniques for imaging of the carotid arteries, colour doppler ultrasound and magnetic resonance angiography (MRA), have disadvantages such that conventional preoperative carotid angiography continues to be done. Doppler fails to provide the
CTA in
severe
stenosis.
Short segment of subtotal occlusion is visible in carotid artery
surgeon with
proximal left internal
overview of the carotid circulation and may or give a false diagnosis of carotid occlusion.2,3 MRA tends to overestimate the degree and length of stenosis because of signal loss in the stenotic segment. 4,5 We describe a non-invasive computed tomographic angiography (CTA) technique that may overcome some of these limitations. A newly developed slip-ring CT scanner capable of 50 rotations in 50 s is used (Tomoscan SR-HP, Philips Medical Systems). With a table increment of 3 mm/s, maximum of 150 3 rnm slices overlapping 2 mm with each adjacent slice can be acquired in under 1 min. 120 ml intravenous contrast material is administered via an antecubital vein at 1-5 to 2.0 ml/s. The angiographic image is produced on an independent 3-D workstation (Gryoview, Philips Medical Systems) with these CT images (figure). The densely opacified carotid lumen can be recognised automatically by the reconstruction program, so that segmentation and reconstruction takes only 30-45 min. CTA allows the non-invasive production of an angiographic image without the risks and costs of conventional angiography. The sensitivity and specificity of this technique are not yet known, but preliminary results are promising. As CTA is further refined, it may be possible to reduce the need for preoperative carotid an
underdiagnose distal plaques
angiography.
Departments of Diagnostic Radiology and Surgery, University Hospital of Utrecht, 3584 CX Utrecht, Netherlands
EVAN H. DILLON MAARTEN S. VAN LEEUWEN M. ARANCHA FERNANDEZ BERT C. EIKELBOOM WILLEM TH. MALI
1. Earnest F, Forbes
G, Sandok BA, et al. Complications of cerebral angiography prospective assessment of risk. AJR 1984; 142: 247-52. 2. Erickson SJ, Mewissen MW, Foley WD, et al. Stenosis of the internal carotid artery: assessment using color Doppler imaging compared with angiography. AJR 1989; 152: 1299-305. W, Kloetzsch C, Hennerici M. Carotid artery disease assessed by color Doppler flow imaging: correlation with standard Doppler sonography and angiography. AJR 1990; 154: 1061-68. 4. Riles TS, Eidelman EM, Litt AW, Pinto RS, Oldford F, Thoe Schwartzenberg GWS. Comparison of magnetic resonance angiography, conventional angiography, and duplex scanning. Stroke 1992; 23: 341-46. 5. Anderson CM, Saloner D, Lee RE, et al. Assessment of carotid artery stenosis by MR angiography: comparison with X-ray angiography and color-coded Doppler ultrasound. AJNR 1992; 13: 989-1003. 3. Steinke
