Radiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Published online before print November 22, 2005, 10.1148/radiol.2381041649

(Radiology 2005;238:604.)

A more recent version of this article appeared on January 1, 2005
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow All Versions of this Article:
2381041649v1
238/2/604    most recent
Right arrow Submit a response
Right arrow View responses
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dubrulle, F.
Right arrow Articles by Vincent, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dubrulle, F.
Right arrow Articles by Vincent, C.
© RSNA, 2005

Head and Neck Imaging

Diffusion-weighted MR Imaging Sequence in the Detection of Postoperative Recurrent Cholesteatoma1

Frederique Dubrulle, MD, Raphaelle Souillard, MD, David Chechin, PhD, François M. Vaneecloo, MD, Alain Desaulty, MD and Christophe Vincent, MD

1 From the Departments of Radiology (F.D., R.S.), Otology and Otoneurosurgery (C.V., F.M.V.), and Otolaryngology (A.D.), Centre Hospitalier Universitaire, Lille, France; and Philips Medical Systems, Suresnes, France (D.C.). Received September 24, 2004; revision requested November 30; revision received January 21, 2005; accepted February 21; final version accepted March 18. Address correspondence to: F.D., Plateau Commun d'Imagerie, Hôpital Claude Huriez Centre Sud, Rue Michel Polonovski, 59037 Lille Cedex, France (e-mail: f-dubrulle{at}chru-lille.fr).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Purpose: To prospectively evaluate a fast spin-echo (SE) diffusion-weighted sequence for magnetic resonance (MR) imaging of recurrent cholesteatoma in patients who have undergone middle ear surgery.

Materials and Methods: The study was approved by the institutional review board, and informed consent was obtained from all patients. Twenty-four patients (10 female and 14 male patients; mean age, 44 years) who had undergone resection of cholesteatoma were referred for MR imaging. MR imaging was performed with a 1.5-T unit by using unenhanced diffusion-weighted fast SE imaging at b factors of 0 and 800 sec/mm2, unenhanced T2-weighted fast SE imaging, unenhanced T1-weighted SE imaging, and delayed contrast material–enhanced T1-weighted imaging. Two radiologists evaluated the diffusion-weighted fast SE images for the presence of a high-signal-intensity cholesteatoma. Results from MR imaging were compared with reports from second- or third-look surgery. Interobserver agreement was assessed with the {kappa} statistic.

Results: A recurrent cholesteatoma was correctly identified in 13 of 14 patients with diffusion-weighted fast SE images obtained with a b factor of 800 sec/mm2, for a positive predictive value of 93%. In patients without recurrent cholesteatoma, all diffusion-weighted fast SE MR images obtained with a b factor of 800 sec/mm2 were correctly interpreted as showing no high signal intensity. Thus, the negative predictive value was 100%. Sensitivity and specificity were 100% (13 of 13 patients) and 91% (10 of 11 patients), respectively. Interobserver agreement was excellent ({kappa} = 0.92). The smallest recurrent cholesteatoma was 5 mm in diameter, and this was correctly detected with the diffusion-weighted fast SE sequence.

Conclusion: Diffusion-weighted fast SE imaging enables the depiction of recurrent cholesteatoma in patients who have undergone middle ear surgery.

© RSNA, 2005


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
The imaging follow-up of patients who have undergone middle ear surgery for a cholesteatoma is a basic examination to detect recurrent cholesteatoma. Thin-section computed tomography (CT) is the method of choice in the analysis of middle ear attenuation in the three orthogonal planes. When the postoperative cavity is completely filled with a soft-tissue mass or partially filled with nonspecific imaging abnormalities, however, CT is not reliable (1–5). The soft-tissue mass can be caused by recurrent cholesteatoma, granulation, or fibrous tissue, which are common after surgery, or both cholesteatoma and granulation tissue. Middle ear surgery is necessary if recurrent cholesteatoma is diagnosed (6) but not if granulation tissue is detected. Several studies have demonstrated the role of magnetic resonance (MR) imaging in the differentiation of recurrent cholesteatoma from granulation tissue (7–10), especially with a delayed contrast material–enhanced T1-weighted spin-echo (SE) sequence (11). Other studies have emphasized the importance of diffusion-weighted MR imaging in the detection of recurrent cholesteatoma (12–14). Diffusion-weighted echo-planar MR imaging, however, has a low spatial resolution and important susceptibility artifacts. Thus, the purpose of our study was to prospectively evaluate a diffusion-weighted fast SE sequence for MR imaging of recurrent cholesteatoma in patients who have undergone middle ear surgery.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 References
 
Patients
We evaluated 24 consecutive patients (10 female and 14 male patients; mean age, 44 years; age range, 15–71 years) who had undergone a canal wall-down mastoidectomy or a canal wall-up mastoidectomy for a cholesteatoma of the middle ear and underwent an MR examination before second- or third-look surgery from April 2002 to June 2004. The second- or third-look surgery was performed within 5 months after the MR examination. Informed consent was obtained from all patients. Our study was approved by our institutional review board.

Imaging Technique
MR imaging was performed with a 1.5-T MR unit (Intera; Philips Medical Systems, Best, the Netherlands). Transverse and coronal T2-weighted fast SE images (3500/120 [repetition time msec/echo time msec], 14 sections, 1.7-mm-thick sections, 230-mm field of view, 336 x 512 matrix, fast SE factor of 17, 90° flip angle, six signals acquired, imaging time of 4 minutes 26 seconds) and coronal T1-weighted SE images (500/16, 14 sections, 1.7-mm-thick sections, 250-mm field of view, 336 x 512 matrix, 73° flip angle, three signals acquired, imaging time of 4 minutes 59 seconds) were obtained before the administration of contrast material. Coronal multishot diffusion-weighted fast SE images were obtained with nine sections, 2.5-mm-thick sections, 230-mm field of view, 192 x 256 reconstruction matrix, rectangular field of view of 75%, fast SE factor of 14, one signal acquired, an imaging time of 3 minutes 38 seconds, and b factors of 0 and 800 sec/mm2 without measurement of the apparent diffusion coefficient. Immediately after intravenous injection of 0.1 mmol per kilogram of body weight of gadoterate meglumine (Dotarem; Guerbet, Roissy, France), transverse and coronal T1-weighted SE images were obtained with the same parameters as those used before contrast material administration. Coronal delayed contrast-enhanced T1-weighted SE images were obtained 45–60 minutes after contrast material administration.

Imaging Evaluation
MR images were analyzed independently by two radiologists (F.D. and R.S., with 10 and 2 years of experience, respectively, in MR imaging of the middle ear). Both radiologists paid special attention to the susceptibility artifacts with the diffusion-weighted fast SE sequence. The size of the lesion was measured in the greatest transverse diameter on coronal delayed contrast-enhanced T1-weighted SE images.

Cholesterol granuloma was diagnosed if the lesion had high signal intensity on unenhanced T1-weighted images, no change in signal intensity on delayed contrast-enhanced T1-weighted images, and low signal intensity on diffusion-weighted images obtained with a b factor of 800 sec/mm2. Granulation tissue without recurrence of cholesteatoma was diagnosed if the lesion had low signal intensity on unenhanced T1-weighted images, had high signal intensity on T2-weighted images, showed enhancement on delayed contrast-enhanced T1-weighted images, and had low signal intensity on diffusion-weighted images obtained with a b factor of 800 sec/mm2 (Fig 1). Recurrent cholesteatoma was diagnosed if the lesion had low signal intensity on unenhanced T1-weighted images, showed no change in signal intensity on delayed contrast-enhanced T1-weighted images, and had high signal intensity on diffusion-weighted images obtained with a b factor of 800 sec/mm2 (Figs 2, 3).



View larger version (154K):
[in this window]
[in a new window]
  		Figure 1a: MR images of granulation tissue of the left middle ear in a 44-year-old man. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows high-signal-intensity soft tissue (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows mild enhancement of the soft tissue (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the soft tissue (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows low signal intensity of the soft tissue (arrow).

 


View larger version (148K):
[in this window]
[in a new window]
  		Figure 1b: MR images of granulation tissue of the left middle ear in a 44-year-old man. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows high-signal-intensity soft tissue (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows mild enhancement of the soft tissue (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the soft tissue (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows low signal intensity of the soft tissue (arrow).

 


View larger version (137K):
[in this window]
[in a new window]
  		Figure 1c: MR images of granulation tissue of the left middle ear in a 44-year-old man. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows high-signal-intensity soft tissue (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows mild enhancement of the soft tissue (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the soft tissue (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows low signal intensity of the soft tissue (arrow).

 


View larger version (140K):
[in this window]
[in a new window]
  		Figure 1d: MR images of granulation tissue of the left middle ear in a 44-year-old man. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows high-signal-intensity soft tissue (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows mild enhancement of the soft tissue (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the soft tissue (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows low signal intensity of the soft tissue (arrow).

 


View larger version (163K):
[in this window]
[in a new window]
  		Figure 2a: MR images of recurrent cholesteatoma in the left middle ear of a 20-year-old man who underwent a canal wall-down mastoidectomy. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows a large high-signal-intensity tissue mass (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the tissue mass (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the tissue mass (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the recurrent cholesteatoma (arrow).

 


View larger version (164K):
[in this window]
[in a new window]
  		Figure 2b: MR images of recurrent cholesteatoma in the left middle ear of a 20-year-old man who underwent a canal wall-down mastoidectomy. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows a large high-signal-intensity tissue mass (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the tissue mass (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the tissue mass (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the recurrent cholesteatoma (arrow).

 


View larger version (127K):
[in this window]
[in a new window]
  		Figure 2c: MR images of recurrent cholesteatoma in the left middle ear of a 20-year-old man who underwent a canal wall-down mastoidectomy. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows a large high-signal-intensity tissue mass (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the tissue mass (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the tissue mass (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the recurrent cholesteatoma (arrow).

 


View larger version (147K):
[in this window]
[in a new window]
  		Figure 2d: MR images of recurrent cholesteatoma in the left middle ear of a 20-year-old man who underwent a canal wall-down mastoidectomy. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows a large high-signal-intensity tissue mass (arrow). (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the tissue mass (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of the tissue mass (arrow). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the recurrent cholesteatoma (arrow).

 


View larger version (120K):
[in this window]
[in a new window]
  		Figure 3a: MR images of recurrent cholesteatoma in the left middle ear and granulation tissue in the right middle ear of a 16-year-old girl who underwent middle ear surgery in both ears. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows areas of high signal intensity (arrows) in both middle ears. (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the recurrent cholesteatoma in the left middle ear (arrowhead) and enhancement of the granulation tissue in the right middle ear (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows areas of high signal intensity in both middle ears (arrows). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the cholesteatoma in the left middle ear (arrowhead), whereas the granulation tissue in the right middle ear (arrow) has low signal intensity.

 


View larger version (112K):
[in this window]
[in a new window]
  		Figure 3b: MR images of recurrent cholesteatoma in the left middle ear and granulation tissue in the right middle ear of a 16-year-old girl who underwent middle ear surgery in both ears. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows areas of high signal intensity (arrows) in both middle ears. (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the recurrent cholesteatoma in the left middle ear (arrowhead) and enhancement of the granulation tissue in the right middle ear (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows areas of high signal intensity in both middle ears (arrows). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the cholesteatoma in the left middle ear (arrowhead), whereas the granulation tissue in the right middle ear (arrow) has low signal intensity.

 


View larger version (110K):
[in this window]
[in a new window]
  		Figure 3c: MR images of recurrent cholesteatoma in the left middle ear and granulation tissue in the right middle ear of a 16-year-old girl who underwent middle ear surgery in both ears. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows areas of high signal intensity (arrows) in both middle ears. (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the recurrent cholesteatoma in the left middle ear (arrowhead) and enhancement of the granulation tissue in the right middle ear (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows areas of high signal intensity in both middle ears (arrows). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the cholesteatoma in the left middle ear (arrowhead), whereas the granulation tissue in the right middle ear (arrow) has low signal intensity.

 


View larger version (106K):
[in this window]
[in a new window]
  		Figure 3d: MR images of recurrent cholesteatoma in the left middle ear and granulation tissue in the right middle ear of a 16-year-old girl who underwent middle ear surgery in both ears. (a) Coronal T2-weighted fast SE image (3500/120, 1.7-mm-thick sections) shows areas of high signal intensity (arrows) in both middle ears. (b) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the recurrent cholesteatoma in the left middle ear (arrowhead) and enhancement of the granulation tissue in the right middle ear (arrow). (c) Coronal diffusion-weighted fast SE image obtained with a b factor of 0 sec/mm2 (2.5-mm-thick sections) shows areas of high signal intensity in both middle ears (arrows). (d) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows markedly high signal intensity of the cholesteatoma in the left middle ear (arrowhead), whereas the granulation tissue in the right middle ear (arrow) has low signal intensity.

 
The surgical findings were obtained from the surgical reports of two different teams: one team of otoneurology surgeons (F.M.V., C.V.) and another team of otology surgeons (A.D.). Two radiologists (F.D., R.S.) compared the findings at surgery with those at MR imaging. The surgical results were classified as recurrence of cholesteatoma or no recurrence of cholesteatoma.

Statistical Analysis
Sensitivity, specificity, and positive and negative predictive values were evaluated separately for delayed contrast-enhanced T1-weighted SE images and diffusion-weighted fast SE images obtained with a b factor of 800 sec/mm2 and compared with findings from second- or third-look surgery. Interobserver agreement was assessed by using the {kappa} statistic and computed with SAS software (version 8.2; SAS Institute, Cary, NC), with a P value of less than .01 considered to indicate a statistically significant difference.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 References
 
Comparison of MR Imaging and Surgery
In 10 of 24 patients, no recurrence of cholesteatoma was diagnosed at MR imaging: The middle ear lesion had low signal intensity on unenhanced T1-weighted images, showed enhancement on delayed contrast-enhanced T1-weighted images, and had low signal intensity on diffusion-weighted images obtained with a b factor of 800 sec/mm2 compared with diffusion-weighted images obtained with a b factor of 0 sec/mm2. In these 10 patients, no recurrent cholesteatoma was found at surgery. As a result, the negative predictive value was 100%.

In 14 patients, recurrence of cholesteatoma was diagnosed at MR imaging. The lesion had low signal intensity on unenhanced T1-weighted images, showed no change in signal intensity on delayed contrast-enhanced T1-weighted images, and had high signal intensity on diffusion-weighted images obtained with a b factor of 800 sec/mm2. Recurrent cholestreatoma was diagnosed at surgery in 13 of these 14 patients (13 true-positive cases). The size and location of the cholesteatoma analyzed at MR imaging were in agreement with those found at surgery. The lesion size ranged from 5 to 24 mm.

There was one false-positive finding, a 7 x 5-mm tympanic attical lesion that was not a recurrent cholesteatoma but bone powder placed during the initial surgery to fill a lateral semicircular canal fistula. As a result, the positive predictive value was 93% (13 of 14 patients). No cholesterol granuloma was diagnosed at MR imaging or surgery in the 24 patients.

Reader and Image Sequence Comparisons
No disagreement was seen between the interpretations of the two radiologists (F.D., R.S.) or the results of delayed contrast-enhanced T1-weighted imaging, which is a valuable tool (11) in the detection of recurrent cholesteatoma, and diffusion-weighted fast SE imaging. The false-positive case in our study appeared to show false results on both delayed contrast-enhanced T1-weighted images and diffusion-weighted fast SE images.

Very few susceptibility artifacts were present on diffusion-weighted fast SE images. In particular, there were no air-bone interface artifacts. The diffusion-weighted fast SE sequence enabled us to detect very small recurrent cholesteatomas with diameters of 5–10 mm (Fig 4 ).



View larger version (157K):
[in this window]
[in a new window]
  		Figure 4a: MR images of a small recurrent cholesteatoma in the right middle ear of a 48-year-old woman who underwent a canal wall-down mastoidectomy. (a) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the tissue mass (arrow). (b) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of this small 7-mm-diameter cholesteatoma (arrow) of the posterior cavity.

 


View larger version (176K):
[in this window]
[in a new window]
  		Figure 4b: MR images of a small recurrent cholesteatoma in the right middle ear of a 48-year-old woman who underwent a canal wall-down mastoidectomy. (a) Coronal delayed contrast-enhanced T1-weighted SE image (500/16, 1.7-mm-thick sections) shows no enhancement of the tissue mass (arrow). (b) Coronal diffusion-weighted fast SE image obtained with a b factor of 800 sec/mm2 (2.5-mm-thick sections) shows high signal intensity of this small 7-mm-diameter cholesteatoma (arrow) of the posterior cavity.

 
Finally, the results with diffusion-weighted fast SE imaging were similar to those with delayed contrast-enhanced T1-weighted imaging. Sensitivity and specificity with diffusion-weighted fast SE imaging were 100% and 91%, respectively. The positive and negative predictive values were 93% and 100%, respectively. Interobserver agreement was excellent ({kappa} = 0.92) (Table).


View this table:
[in this window]
[in a new window]
  		Correlation of Surgical and MR Imaging Findings

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
References
 
Histopathologically, a cholesteatoma is an enlarging collection of exfoliated keratin within a sac of stratified squamous epithelium (15) that shows no change in signal intensity on contrast-enhanced MR images. Conversely, granulation tissue shows enhancement only on delayed contrast-enhanced images owing to its fibrous nature and, possibly, to the microvascular thrombosis phenomenon (11). It is necessary to obtain delayed contrast-enhanced images with a delay of 30–45 minutes after contrast material administration. In a study of 18 patients (11), the positive predictive value was 92.6% for delayed contrast-enhanced MR imaging.

The importance of diffusion-weighted MR imaging in the detection of recurrent cholesteatoma has been reported in several previous studies (12–14). Cholesteatoma has high signal intensity on diffusion-weighted images obtained with b factors of 800 or 1000 sec/mm2, whereas granulation tissue has low signal intensity. Results of previous studies (14,16) have proved that visual comparison of diffusion-weighted images obtained with a b factor of 800 sec/mm2 without measurement of the apparent diffusion coefficient is sufficient for analysis of the diffusion-weighted sequence. Diffusion-weighted MR imaging provides information regarding diffusion motion of water protons in biologic tissues (17). Several interpretations to explain the high signal intensity of cholesteatoma on diffusion-weighted images have been proposed. Several studies (18,19) have reported high signal intensity in epidermoid cysts on diffusion-weighted MR images. Two mechanisms have been discussed for this high signal intensity: restricted molecular diffusion and T2 shine-through effects. The reason for the increased signal intensity of cholesteatoma on diffusion-weighted MR images is still unknown but seems to be similar to that for the increased signal intensity of epidermoid cysts on diffusion-weighted images (20).

The point is that only cholesteatoma shows high signal intensity on diffusion-weighted MR images. Other tissues that can be found in the middle ear cavity after surgery—such as granulation tissue, fibrous tissue, cholesterol granuloma, or serous fluid—show low signal intensity on diffusion-weighted MR images.

All previous studies performed to assess the value of a diffusion-weighted MR imaging sequence in the differentiation of recurrent cholesteatoma from granulation tissue (12–14) also showed the low spatial resolution of diffusion-weighted echo-planar images with a small matrix (96 x 200 reconstruction matrix), a section thickness of 4 mm, and, especially, numerous susceptibility artifacts that create high signal intensity in the air-bone interfaces or in the posterior fossa.

The diffusion-weighted fast SE sequence appeared to show few artifacts at the air-bone interfaces. Although diffusion-weighted echo-planar imaging is characterized by a train of gradient echoes with a short echo time and a good signal-to-noise ratio, there are important magnetic susceptibility artifacts. The diffusion-weighted fast SE MR sequence is a multishot sequence characterized by multiple 180° refocusing pulses. It has a longer echo time and a lower signal-to-noise ratio than does the echo-planar sequence. Diffusion-weighted fast SE imaging, however, does not show the susceptibility artifacts that were observed with diffusion-weighted echo-planar imaging. It was useful to obtain a better spatial resolution in the middle ear area, which is full of susceptibility artifacts because of artifacts from the air-bone and air-tissue interfaces. This is the reason we chose the diffusion-weighted fast SE sequence, which is a multishot sequence with a pixel size of 1.2 x 1.23 x 2.5 mm and an acceptable imaging time and signal-to-noise ratio. In addition, coronal diffusion-weighted fast SE imaging appears to show few artifacts. This sequence enabled us to analyze 5-mm-diameter middle ear lesions. The spatial resolution of the diffusion-weighted fast SE sequence with a 192 x 256 reconstruction matrix and a section thickness of 2.5 mm was superior to that of the diffusion-weighted echo-planar sequence but inferior to that of a thin-section T1-weighted SE sequence with a 336 x 512 reconstruction matrix and a section thickness of 1.7 mm. This difference in spatial resolution, however, did not hinder the analysis of lesions.

The results of our study demonstrate the value of the diffusion-weighted fast SE sequence in the detection of recurrent cholesteatoma. In fact, the diffusion-weighted sequence and the delayed contrast-enhanced sequence showed the same results, and no false-negative case was found in our study. This means that when MR imaging showed no evidence of recurrent cholesteatoma, none was found at surgery. The negative predictive value was 100%.

There was one false-positive finding in our study. The false-positive finding occurred with both diffusion-weighted imaging and delayed contrast-enhanced T1-weighted imaging and at surgery appeared to be bone powder placed there during the initial surgery to fill a semicircular canal fistula. It seems to be useful to be aware of the surgical procedures used during the initial surgery before analyzing MR images, especially when a special material such as bone powder has been used.

There were limitations in our study. First, only 24 patients were included in our study. Second, although we used an improved diffusion-weighted sequence to reduce the susceptibility artifacts, image distortions along the phase-encoding direction were unavoidable to some degree. Third, we developed a diffusion-weighted sequence, diffusion-weighted fast SE, that showed very few air-bone interface artifacts. However, we did not directly compare artifacts on diffusion-weighted fast SE images with those on diffusion-weighted echo-planar images for each patient included in our study. Finally, in our practice at our institution, we sometimes have to use MR imaging to analyze middle ear lesions smaller than 5 mm in diameter. Diffusion-weighted images and delayed contrast-enhanced T1-weighted images, however, showed that it was difficult to correctly analyze lesions smaller than 5 mm. This point was noticed in our experience, as well as in other reports (11). In our study, the smallest middle ear lesion was 5 mm in diameter. Thus, additional studies including lesions smaller than 5 mm are needed to define the role of the diffusion-weighted sequence in the detection of small recurrent cholesteatoma.

In conclusion, the results of our study show the reliability of diffusion-weighted fast SE MR imaging in the detection of recurrent cholesteatoma in patients who have undergone middle ear surgery. Our results are similar to those obtained with a delayed contrast-enhanced T1-weighted sequence. The negative predictive value was 100%, which means that patients who show no signs of recurrent cholesteatoma on diffusion-weighted fast SE images may not need second- or third-look surgery systematically.

Further investigations are necessary to determine whether the diffusion-weighted fast SE sequence should become a routine evaluation in MR imaging to differentiate postoperative granulation tissue from recurrent cholesteatoma without use of delayed contrast-enhanced T1-weighted imaging.


   FOOTNOTES
 

Abbreviations: SE = spin echo

Authors stated no financial relationship to disclose.

Author contributions: Guarantors of integrity of entire study, F.D., R.S.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, F.D., R.S.; clinical studies, all authors; and manuscript editing, F.D., R.S.


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 

  1. Czerny C, Turetschek K, Duman M, Imhof H. Imaging of the middle ear: CT and MRI [in German]. Radiologe 1997;37:945–953.[CrossRef][Medline]
  2. Campbell JP, Pillsbury HC. The use of computerized tomographic imaging in revision mastoid surgery for chronic otitis media. Am J Otol 1990;11:387–394.[Medline]
  3. Blaney SP, Tierney P, Oyarazabal M, Bowdler DA. CT scanning in "second look" combined approach tympanoplasty. Rev Laryngol Otol Rhinol (Bord) 2000;121:79–81.
  4. Wake M, Robinson JM, Witcombe JB, Bazerbachi S, Stansbie JM, Phelps PD. Detection of recurrent cholesteatoma by computerized tomography after "closed cavity" mastoid surgery. J Laryngol Otol 1992;106:393–395.[Medline]
  5. Tierney PA, Pracy P, Blaney SP, Bowdler DA. An assessment of the value of the preoperative computed tomography scans prior to otoendoscopic "second look" in intact canal wall mastoid surgery. Clin Otolaryngol Allied Sci 1999;24:274–276.
  6. Sheehy JL, Robinson JV. Revision tympanoplasty: residual and recurrent cholesteatoma—a report on 272 intact canal wall revisions. In: Sade J, ed. Cholesteatoma and mastoid surgery: 2nd International Conference. Amsterdam, the Netherlands: Kugler, 1982; 443–448.
  7. Heran F, Williams M. MRI of the ear. J Neuroradiol 2003;30(3):131–145.[Medline]
  8. Kosling S, Bootz F. CT and MR imaging after middle ear surgery. Eur J Radiol 2001;40(2):113–118.[CrossRef][Medline]
  9. Vanden Abeele D, Coen E, Parizel PM, Van de Heyning P. Can MRI replace a second look operation in cholesteatoma surgery? Acta Otolaryngol 1999;119:555–561.[CrossRef][Medline]
  10. Kimitsuki T, Suda Y, Kawano H, Tono T, Komune S. Correlation between MRI findings and second-look operation in cholesteatoma surgery. ORL J Otorhinolaryngol Relat Spec 2001;63:291–293.[Medline]
  11. Williams MT, Ayache D, Alberti C, et al. Detection of postoperative residual cholesteatoma with delayed contrast-enhanced MR imaging: initial findings. Eur Radiol 2003;13:169–174.[Medline]
  12. Fitzek C, Mewes T, Fitzek S, Mentzel HJ, Hunsche S, Stoeter P. Diffusion-weighted MRI of cholesteatomas of the petrous bone. J Magn Reson Imaging 2002;15(6):636–641.[CrossRef][Medline]
  13. Fitzek CM, Fitzek S, Meves T, Mann W, Stoeter P. Ultrafast MRI examination of cholesteatomas of the petrous bone [abstr]. Eur Radiol 2000;10(suppl):295.
  14. Bergui M, Zhong J, Bradac GB, Sales S. Diffusion-weighted images of intracranial cyst-like lesions. Neuroradiology 2001;43:824–829.[CrossRef][Medline]
  15. Joel D, Swartz H, Haensberger R. Imaging of temporal bone. Stuttgart, Germany: Thieme, 1997; 78.
  16. Aikele P, Kittner T, Offergeld C, Kaftan H, Huttenbrink KB, Laniado M. Diffusion-weighted MR imaging in pediatric and adult patients who have undergone middle ear surgery. AJR Am J Roentgenol 2003;181:261–265.[Abstract/Free Full Text]
  17. Le Bihan D, Breton E, Lallemand D, Grenier P, Cabanis E, Laval-Jeantet M. MR imaging in intravoxel incoherent motions: application to diffusion and perfusion in neurologic disorders. Radiology 1986;161:401–407.[Abstract/Free Full Text]
  18. Schaefer PW, Grant PE, Gonzalez RG. Diffusion-weighted MR imaging of the brain. Radiology 2000;217:331–345.[Abstract/Free Full Text]
  19. Annet L, Duprez T, Grandin C, Dooms G, Collard A, Cosnard G. Apparent diffusion coefficient measurements within intracranial epidermoid cysts in six patients. Neuroradiology 2002;44:326–328.[CrossRef][Medline]
  20. Chen S, Ikawa F, Kurisu K, Takaba J, Kanou Y. Quantitative MR evaluation of intracranial epidermoid tumors by fast fluid-attenuated inversion recovery imaging and echo-planar diffusion-weighted imaging. AJNR Am J Neuroradiol 2001;22:1089–1096.[Abstract/Free Full Text]



eLetters:

Read all eLetters

Optimal Detection of Postoperative Residual Cholesteatoma with MR Imaging
Marc T Williams, MD
Radiology Online, 8 Mar 2006 [Full text]
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow All Versions of this Article:
2381041649v1
238/2/604    most recent
Right arrow Submit a response
Right arrow View responses
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dubrulle, F.
Right arrow Articles by Vincent, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dubrulle, F.
Right arrow Articles by Vincent, C.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
RADIOLOGY RADIOGRAPHICS RSNA JOURNALS ONLINE