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Acute colonic diverticulitis: visualization in magnetic resonance imaging
Magnetic Resonance Imaging 19 (2001) 1275–1277
Acute colonic diverticulitis: Visualization in magnetic resonance imaging Johannes T. Heverhagena,*, Andreas Zielkeb, Natascha Ishaquea, Thomas Bohrerb Michael El-Sheika, Klaus-Jochen Klosea a
Department of Diagnostic Radiology, University Hospital, Philipps University, Marburg, Germany b Department of Surgery, University Hospital, Philipps University, Marburg, Germany Received 21 August 2001; 18 October 2001
Abstract The incidence of acute colonic diverticulitis (ACD) is increasing. To allow rational therapeutic decisions to be made, a timely diagnosis is required. The feasibility of “on-admission-MRI” to establish the diagnosis has not yet been studied. Therefore, a prospective observational study was carried out in 20 patients with an established diagnosis of ACD. The diagnostic criteria for the MRI diagnosis of ACD were the demonstration of at least one diverticulum, pericolic exudation, and edema of the colonic wall. MRI was diagnostic in all but one patient. It is concluded that MRI has considerable diagnostic potential in ACD and should be formally evaluated. © 2001 Elsevier Science Inc. All rights reserved.
1. Introduction The clinical diagnosis of acute colonic diverticulitis (ADC) is at times difficult, but early confirmation is essential for rational management. Assessing site and severity of the disease is particularly important in complicated, i.e., perforated, colonic diverticulitis, since these patients may require urgent surgical therapy. The outcome of surgery largely depends on a timely diagnosis, especially in the elderly. Currently computed tomography (CT) is considered to be the best imaging method in ACD [1], but carries its own restrictions, mainly ionizing radiation, the need for IV injection of iodinated contrast material as well as air or diluted barium sulfate suspension rectally. Ultrasound (US) is particularly attractive because it allows definition of the anatomic extent of extramucosal inflammatory masses and identification of abscesses and other complications without the need for contrast media. As previously published, the sensitivity of US can be as high as 98% with a specificity above 97% in the hands of an expert investigator [2]. The limitations of US lie in the * Corresponding author. Tel.: ⫹1-06421-2866231; fax: ⫹1-064212868959. E-mail address: [email protected] (J.T. Heverhagen).
“unhappy triad” of too much pain, too much gas and too much fat, as well as the incapability of distinguishing between neoplastic and inflammatory tumors. The need for an expert investigator, especially in these difficult cases, further impairs the efficiency of US. Despite these drawbacks of both modalities, CT is currently the initial imaging approach in the U.S., whereas US is applied first in Europe. Magnetic resonance imaging (MRI) promises to overcome some of these drawbacks. MRI is able to depict inflammatory changes and ascites due to the fluid sensitivity of heavily T2-weighted sequences. By virtue of its high resolution, MRI allows visualization of even small diverticula and segmental narrowing of the colon. Additionally, MRI allows the examination of the entire colon in just one session. In patients with acute appendicitis Incesu et al. [3] reported a sensitivity of 97% and specificity of 100%. It would thus appear that MRI could be useful in patients with suspected acute colonic diverticulitis. A previous study that included only patients with known ACD indicated that STIR and TrueFisp images are are sufficient to establish the diagnosis of ACD [4]. Additionally, application of single-shot T2 weighted fat suppressed imaging did not lead to a further improvement in diagnostic accuracy.
0730-725X/01/$ – see front matter © 2001 Elsevier Science Inc. All rights reserved. PII: S 0 7 3 0 - 7 2 5 X ( 0 1 ) 0 0 4 6 9 - 6
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J.T. Heverhagen et al. / Magnetic Resonance Imaging 19 (2001) 1275–1277
2. Materials and methods We included 20 patients (11 women/9 men; 54.8 ⫾ 14.6 years) in a prospective observational feasibility study. Prior to inclusion in the study, informed consent was obtained from all patients. All patients had typical clinical signs of acute diverticulitis, i.e., lower left quadrant pain and localized peritonitis. The clinical diagnosis was confirmed by ultrasound (SSH 140, Toshiba, Japan) in all cases carried out by a single experienced investigator and at least one other established modality in the clinical course, e.g., CT, endoluminal ultrasound or surgery. The study was approved by the institutional review board. MR imaging was carried out with a 1.0 T clinical scanner (Magnetom Expert™, Siemens, Erlangen, Germany) using a circular polarized body array coil. Images were acquired with T2-weighted gradient echo (TrueFisp; TR: 10.2 ms, TE: 4.7 ms, FA: 80°) and inversion recovery (STIR; TR: 6200 ms, TE: 60 ms, FA: 120°) sequences in the coronal plane. Single shot T2 weighted fat suppressed images, that seem to be beneficial in ACD, were not applied because a previous study showed inferior diagnostic capability of these sequences in ACD [4]. Immediately prior to MR imaging, 40 mg Butylscopolaminiumbromid (BuscopanTM, Boehringer Ingelheim Pharma KG, Ingelheim, Germany) were administered i.v. to prevent motion artifacts due to peristalsis of the colon. MR images were evaluated by one experienced reader blinded to the results of all other investigations. The specific MR imaging diagnosis of acute diverticulitis was based on demonstration of a least one diverticulum, pericolic exudation and edema of the colonic wall. Additional findings of segmental narrowing and ascites were also considered to be supportive of the diagnosis (Fig. 1). All findings were evaluated qualitatively. The reader stated presence or absence of each finding.
3. Results US showed diverticula in all patients located in the left colon (19 cases) or the right colon (1 case). Hypoechogenic thickening of the colon wall with a mean of 10.4 ⫾ 3.3 mm was demonstrated. The length of the involved segments was 70.9 ⫾ 28.1 mm. US depicted inflamed diverticula in all patients, and segmental narrowing in 17. These findings were verified in 15 cases by CT, in one case by endoluminal ultrasound and in four cases by surgery. All patients tolerated scanning during a mean scan time of 15.2 ⫾ 5.2 min. In 19 patients MRI depicted diverticula, edema and pericolic exudation. Both sequences showed these findings, whereas edema and pericolic exudation were easier demonstrated in the STIR images. Seventeen patients showed segmental narrowing and ascites was delineated in two patients. TrueFisp images enabled the depiction of segmental narrowing, whereas STIR images displayed ascites more clearly. Based on the MRI results 19 patients
Fig. 1. (a) Fluid-sensitive STIR image in the coronal pland and (b) TRUEFISP sequence offering a better contrast to solid organs. Demonstrated are diverticula (large black arrow), segmental narrowing of the colon (small black arrows), (white arrows), paracolonic exudation (black asterisk) and colonic wall thickening (large white arrowheads). The TRUE-FISP image visualizes the paracolic exudation as “dirty fat” sign (small white arrowheads).
were identified as suffering from diverticulitis, with equivocal findings in only one patient. 4. Discussion Computed tomography is the diagnostic goldstandard in the diagnosis of acute diverticulitis [1,5]. Many authors also
J.T. Heverhagen et al. / Magnetic Resonance Imaging 19 (2001) 1275–1277
used ultrasound or contrast enema examinations [2,6 – 8]. Efficacy of MRI has not yet been mentioned in the literature. However, some authors investigated adults [3] and children [9] with suspected acute appendicitis that shows similar diagnostic signs as acute diverticulitis. They reported sensitivities and specificities up to 100%. Comparing ultrasound and computed tomography, it is reported that both modalities possess the same diagnostic value [5]. In diagnosis of acute diverticulitis an accuracy of 84% was refered. Ultrasound has a superior specificity of 84% in comparison with 77% for computed tomography, whereas computed tomography showed a better sensitivity of 91% compared to 85% for ultrasound. Clearly, this study is limited by the small number of patients, all of which were already confirmed as having diverticulitis. However, we chose this approach to establish MRI criteria for making the diagnosis of ACD. Abscesses and perforations were not addressed in our preliminary study. It is to be expected that the use of I. V. contrast media and acquisition of high resolution T1-weighted images should allow demonstration of these complications. Our study pointed out the potential advantages of MRI in the diagnosis of ACD. To further evaluate its clinical utility, randomized prospective studies are urgently needed with larger patient populations.
1277
References [1] Rao PM, Rhea JT. Colonic diverticulitis: evaluation of the arrowhead sign and the inflamed diverticulum for CT diagnosis. Radiology 1998;209:775–9. [2] Zielke A, Hasse C, Nies C, Kisker O, Voss M, Sitter H, Rothmund M. Prospective evaluation of ultrasonography in acute colonic diverticulitis. Br J Surg 1997;84:385– 8. [3] Incesu L, Coskun A, Selcuk MB, Akan H, Sozubir S, Bernay F. Acute appendicitis: MR imaging and sonographic correlation. AJR Am J Roentgenol 1997;168:669 –74. [4] Heverhagen JT, Ishaque N, Zielke A, Bohrer T, Sitter H, Berthold LD, Klose KJ. Feasibility of MRI in the diagnosis of acute diverticulitis: initial results. MAGMA 2001;12:4 –9. [5] Pradel JA, Adell JF, Taourel P, Djafari M, Monnin-Delhom E, Bruel JM. Acute colonic diverticulitis: prospective comparative evaluation with US and CT. Radiology 1997;205:503–12. [6] Crone-Munzebrock W, Wegener C, Nicolas V, Pothmann W. The relevance of sonography in the diagnosis of acute abdomen in the intensive care unit. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 1990;153:379 – 84. [7] Riesener KP, Klever P, Truong SN, Schumpelick V. Role of sonography as primary diagnostic method in acute abdomen–a prospective study. Langenbecks Arch Chir Suppl Kongressbd 1997;114:1196 – 8. [8] Paterson-Brown S, Vipond MN. Modern aids to clinical decisionmaking in the acute abdomen. Br J Surg 1990;77:13– 8. [9] Hormann M, Paya K, Eibenberger K, Dorffner R, Lang S, Kreuzer S, Metz VMMR imaging in children with nonperforated acute appendicitis: value of unenhanced MR imaging in sonographically selected casesAJR Am J Roentgenol 1998;171:467–70.
Acute colonic diverticulitis: Visualization in magnetic resonance imaging Johannes T. Heverhagena,*, Andreas Zielkeb, Natascha Ishaquea, Thomas Bohrerb Michael El-Sheika, Klaus-Jochen Klosea a
Department of Diagnostic Radiology, University Hospital, Philipps University, Marburg, Germany b Department of Surgery, University Hospital, Philipps University, Marburg, Germany Received 21 August 2001; 18 October 2001
Abstract The incidence of acute colonic diverticulitis (ACD) is increasing. To allow rational therapeutic decisions to be made, a timely diagnosis is required. The feasibility of “on-admission-MRI” to establish the diagnosis has not yet been studied. Therefore, a prospective observational study was carried out in 20 patients with an established diagnosis of ACD. The diagnostic criteria for the MRI diagnosis of ACD were the demonstration of at least one diverticulum, pericolic exudation, and edema of the colonic wall. MRI was diagnostic in all but one patient. It is concluded that MRI has considerable diagnostic potential in ACD and should be formally evaluated. © 2001 Elsevier Science Inc. All rights reserved.
1. Introduction The clinical diagnosis of acute colonic diverticulitis (ADC) is at times difficult, but early confirmation is essential for rational management. Assessing site and severity of the disease is particularly important in complicated, i.e., perforated, colonic diverticulitis, since these patients may require urgent surgical therapy. The outcome of surgery largely depends on a timely diagnosis, especially in the elderly. Currently computed tomography (CT) is considered to be the best imaging method in ACD [1], but carries its own restrictions, mainly ionizing radiation, the need for IV injection of iodinated contrast material as well as air or diluted barium sulfate suspension rectally. Ultrasound (US) is particularly attractive because it allows definition of the anatomic extent of extramucosal inflammatory masses and identification of abscesses and other complications without the need for contrast media. As previously published, the sensitivity of US can be as high as 98% with a specificity above 97% in the hands of an expert investigator [2]. The limitations of US lie in the * Corresponding author. Tel.: ⫹1-06421-2866231; fax: ⫹1-064212868959. E-mail address: [email protected] (J.T. Heverhagen).
“unhappy triad” of too much pain, too much gas and too much fat, as well as the incapability of distinguishing between neoplastic and inflammatory tumors. The need for an expert investigator, especially in these difficult cases, further impairs the efficiency of US. Despite these drawbacks of both modalities, CT is currently the initial imaging approach in the U.S., whereas US is applied first in Europe. Magnetic resonance imaging (MRI) promises to overcome some of these drawbacks. MRI is able to depict inflammatory changes and ascites due to the fluid sensitivity of heavily T2-weighted sequences. By virtue of its high resolution, MRI allows visualization of even small diverticula and segmental narrowing of the colon. Additionally, MRI allows the examination of the entire colon in just one session. In patients with acute appendicitis Incesu et al. [3] reported a sensitivity of 97% and specificity of 100%. It would thus appear that MRI could be useful in patients with suspected acute colonic diverticulitis. A previous study that included only patients with known ACD indicated that STIR and TrueFisp images are are sufficient to establish the diagnosis of ACD [4]. Additionally, application of single-shot T2 weighted fat suppressed imaging did not lead to a further improvement in diagnostic accuracy.
0730-725X/01/$ – see front matter © 2001 Elsevier Science Inc. All rights reserved. PII: S 0 7 3 0 - 7 2 5 X ( 0 1 ) 0 0 4 6 9 - 6
1276
J.T. Heverhagen et al. / Magnetic Resonance Imaging 19 (2001) 1275–1277
2. Materials and methods We included 20 patients (11 women/9 men; 54.8 ⫾ 14.6 years) in a prospective observational feasibility study. Prior to inclusion in the study, informed consent was obtained from all patients. All patients had typical clinical signs of acute diverticulitis, i.e., lower left quadrant pain and localized peritonitis. The clinical diagnosis was confirmed by ultrasound (SSH 140, Toshiba, Japan) in all cases carried out by a single experienced investigator and at least one other established modality in the clinical course, e.g., CT, endoluminal ultrasound or surgery. The study was approved by the institutional review board. MR imaging was carried out with a 1.0 T clinical scanner (Magnetom Expert™, Siemens, Erlangen, Germany) using a circular polarized body array coil. Images were acquired with T2-weighted gradient echo (TrueFisp; TR: 10.2 ms, TE: 4.7 ms, FA: 80°) and inversion recovery (STIR; TR: 6200 ms, TE: 60 ms, FA: 120°) sequences in the coronal plane. Single shot T2 weighted fat suppressed images, that seem to be beneficial in ACD, were not applied because a previous study showed inferior diagnostic capability of these sequences in ACD [4]. Immediately prior to MR imaging, 40 mg Butylscopolaminiumbromid (BuscopanTM, Boehringer Ingelheim Pharma KG, Ingelheim, Germany) were administered i.v. to prevent motion artifacts due to peristalsis of the colon. MR images were evaluated by one experienced reader blinded to the results of all other investigations. The specific MR imaging diagnosis of acute diverticulitis was based on demonstration of a least one diverticulum, pericolic exudation and edema of the colonic wall. Additional findings of segmental narrowing and ascites were also considered to be supportive of the diagnosis (Fig. 1). All findings were evaluated qualitatively. The reader stated presence or absence of each finding.
3. Results US showed diverticula in all patients located in the left colon (19 cases) or the right colon (1 case). Hypoechogenic thickening of the colon wall with a mean of 10.4 ⫾ 3.3 mm was demonstrated. The length of the involved segments was 70.9 ⫾ 28.1 mm. US depicted inflamed diverticula in all patients, and segmental narrowing in 17. These findings were verified in 15 cases by CT, in one case by endoluminal ultrasound and in four cases by surgery. All patients tolerated scanning during a mean scan time of 15.2 ⫾ 5.2 min. In 19 patients MRI depicted diverticula, edema and pericolic exudation. Both sequences showed these findings, whereas edema and pericolic exudation were easier demonstrated in the STIR images. Seventeen patients showed segmental narrowing and ascites was delineated in two patients. TrueFisp images enabled the depiction of segmental narrowing, whereas STIR images displayed ascites more clearly. Based on the MRI results 19 patients
Fig. 1. (a) Fluid-sensitive STIR image in the coronal pland and (b) TRUEFISP sequence offering a better contrast to solid organs. Demonstrated are diverticula (large black arrow), segmental narrowing of the colon (small black arrows), (white arrows), paracolonic exudation (black asterisk) and colonic wall thickening (large white arrowheads). The TRUE-FISP image visualizes the paracolic exudation as “dirty fat” sign (small white arrowheads).
were identified as suffering from diverticulitis, with equivocal findings in only one patient. 4. Discussion Computed tomography is the diagnostic goldstandard in the diagnosis of acute diverticulitis [1,5]. Many authors also
J.T. Heverhagen et al. / Magnetic Resonance Imaging 19 (2001) 1275–1277
used ultrasound or contrast enema examinations [2,6 – 8]. Efficacy of MRI has not yet been mentioned in the literature. However, some authors investigated adults [3] and children [9] with suspected acute appendicitis that shows similar diagnostic signs as acute diverticulitis. They reported sensitivities and specificities up to 100%. Comparing ultrasound and computed tomography, it is reported that both modalities possess the same diagnostic value [5]. In diagnosis of acute diverticulitis an accuracy of 84% was refered. Ultrasound has a superior specificity of 84% in comparison with 77% for computed tomography, whereas computed tomography showed a better sensitivity of 91% compared to 85% for ultrasound. Clearly, this study is limited by the small number of patients, all of which were already confirmed as having diverticulitis. However, we chose this approach to establish MRI criteria for making the diagnosis of ACD. Abscesses and perforations were not addressed in our preliminary study. It is to be expected that the use of I. V. contrast media and acquisition of high resolution T1-weighted images should allow demonstration of these complications. Our study pointed out the potential advantages of MRI in the diagnosis of ACD. To further evaluate its clinical utility, randomized prospective studies are urgently needed with larger patient populations.
1277
References [1] Rao PM, Rhea JT. Colonic diverticulitis: evaluation of the arrowhead sign and the inflamed diverticulum for CT diagnosis. Radiology 1998;209:775–9. [2] Zielke A, Hasse C, Nies C, Kisker O, Voss M, Sitter H, Rothmund M. Prospective evaluation of ultrasonography in acute colonic diverticulitis. Br J Surg 1997;84:385– 8. [3] Incesu L, Coskun A, Selcuk MB, Akan H, Sozubir S, Bernay F. Acute appendicitis: MR imaging and sonographic correlation. AJR Am J Roentgenol 1997;168:669 –74. [4] Heverhagen JT, Ishaque N, Zielke A, Bohrer T, Sitter H, Berthold LD, Klose KJ. Feasibility of MRI in the diagnosis of acute diverticulitis: initial results. MAGMA 2001;12:4 –9. [5] Pradel JA, Adell JF, Taourel P, Djafari M, Monnin-Delhom E, Bruel JM. Acute colonic diverticulitis: prospective comparative evaluation with US and CT. Radiology 1997;205:503–12. [6] Crone-Munzebrock W, Wegener C, Nicolas V, Pothmann W. The relevance of sonography in the diagnosis of acute abdomen in the intensive care unit. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 1990;153:379 – 84. [7] Riesener KP, Klever P, Truong SN, Schumpelick V. Role of sonography as primary diagnostic method in acute abdomen–a prospective study. Langenbecks Arch Chir Suppl Kongressbd 1997;114:1196 – 8. [8] Paterson-Brown S, Vipond MN. Modern aids to clinical decisionmaking in the acute abdomen. Br J Surg 1990;77:13– 8. [9] Hormann M, Paya K, Eibenberger K, Dorffner R, Lang S, Kreuzer S, Metz VMMR imaging in children with nonperforated acute appendicitis: value of unenhanced MR imaging in sonographically selected casesAJR Am J Roentgenol 1998;171:467–70.