| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Gastrointestinal Imaging |
1 From the Departments of Clinical Radiology (G.B., M.W.B.) and Surgery (A.G.R., D.P.C.), University Hospital of Wales, Cardiff, Wales; the Departments of Histopathology (C.J.R., G.T.W.) and Medical Computing and Statistics (R.G.N.), University of Wales College of Medicine, Cardiff, Wales; and the Department of Histopathology, Llandough Hospital, Cardiff, Wales (N.S.D.). From the 1997 RSNA scientific assembly. Received December 10, 1997; revision requested February 27, 1998; final revision received August 19; accepted October 13. Supported by grants from the Wales Office for Research and Development and by a Fellowship funded by the British United Provident Association through the Royal College of Radiologists. Address reprint requests to G.B., Department of Diagnostic Imaging, Royal Marsden Hospital, Fulham Rd, London SW3 6JJ, England.
 |
Abstract |
|---|
 TOP Abstract IntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
MATERIALS AND METHODS: In a prospective study of 28 consecutive patients, preoperative MR imaging was performed. The tumor stage according to the TNM classification system and the measured depth of extramural tumor invasion in matched MR images and histopathologic slices were compared.
RESULTS: Preoperative MR imaging correctly indicated the histopathologic tumor stage in all 25 patients in whom comparisons were possible. The difference between the depth of extramural tumor measured on preoperative MR images and corresponding measurements on histopathologic slices of the resection specimen ranged from -5.0 mm to +5.5 mm (mean difference, +0.13 mm; 95% CI: -2.72, +2.98 mm), indicating good agreement. The mesorectal fascia, and the relation of the tumor to it, could be visualized in every case. In all five patients with involvement of the circumferential excision margins of resection specimens, extensive extramural invasion was identified on preoperative MR images.
CONCLUSION: Preoperative thin-section MR imaging accurately indicates the tumor stage of rectal cancer and depth of extramural tumor infiltration. It provides valuable information for identifying T3 tumors for preoperative adjuvant therapy in patients who are at high risk of failure of complete excision.
Index terms: Magnetic resonance (MR), thin-section, 757.121411 • Rectum, MR, 757.121411 • Rectum, neoplasms, 757.321 • Rectum, surgery, 757.1261, 757.1267, 757.45
|
Introduction |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
The mesorectal fascia, or fascia propria of the rectum, is a layer of fibroareolar tissue that surrounds the mesorectum. The mesorectum itself is a distinct anatomic unit that is formed during the embryologic period by means of progressive development of the primitive mesenchyma. It comprises the rectum, perirectal fat, blood vessels, nerves, and lymphatic vessels (8,9). Total mesorectal excision is achieved by means of sharp dissection along the plane that separates the visceral from the parietal layers of the perirectal pelvic fascia, thus allowing radical removal of the rectum and its surrounding mesorectum (10).
These advances have greatly increased the importance of accurate preoperative staging in providing information regarding tumor location, size, configuration, and degree of local infiltration. Knowledge of the depth of tumor spread through and beyond the bowel wall influences the selection of patients who will benefit from preoperative adjuvant therapy (11), while reliable spatial information on the tumor's anatomic distribution may facilitate the planning of how such radiation therapy is directed and also of surgical approaches aimed at complete clearance of the tumor.
Currently, endoluminal ultrasonography (US) is considered more accurate than computed tomography or magnetic resonance (MR) imaging for determining tumor extent within and through the wall of the rectum (12). Although studies evaluating endoluminal US have shown high staging accuracies in select patients, the technique is limited by the inability to examine the bulky, stricturing, or high rectal tumors that occur in approximately 20% of cases (13). Moreover, in some cases, only the lower portion of the tumor may be imaged, which can lead to understaging. The same limitations apply to the MR imaging evaluation of rectal tumors by using the endorectal coil (14).
Until now, to our knowledge, studies of conventional MR in imaging rectal tumors have been disappointing because of poor spatial resolution with the body coil. Even a recent report (15) in which the phased-array pelvic coil was used has shown inaccuracies due to an inability to demonstrate the layers of the rectal wall. However, using a four-element surface coil, we have been able to obtain thin-section images with a 0.6 x 0.6-mm in-plane resolution that allow these layers to be visualized and that enable the depth of extramural penetration to be measured. In this study, therefore, we evaluated the diagnostic accuracy of this form of MR imaging in determining the extent of local tumor infiltration by comparing preoperative MR findings with the standard of reference of meticulously matched histopathologic slices of subsequently resected specimens.
|
MATERIALS AND METHODS |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
MR Technique
All patients underwent MR imaging with a 1.5-T whole-body system (Horizon Advantage, software version 5.62; GE Medical Systems, Milwaukee, Wis) with use of a four-element flexible wraparound surface coil (Medical Advances, Milwaukee, Wis). No bowel preparation, air insufflation, or intravenous antispasmodic agents were used. Axial T1-weighted conventional spin-echo images of the pelvis were first obtained by using a 24-cm field of view, a 4-mm section thickness, a 0.5-mm intersection gap, 540/16 (repetition time msec/echo time msec), a 256 x 256 matrix, two signals acquired, no fat saturation, and a 32-kHz bandwidth. Axial and sagittal T2-weighted fast spin-echo acquisitions in the anatomic pelvis were then performed by using a 24-cm field of view, a 5-mm contiguous section thickness, 4,000/85, a 512 x 256 matrix, an echo train length of eight, no fat saturation, a 32-kHz bandwidth, and two signals acquired.
These T1- and T2-weighted images were used to plan T2-weighted thin-section axial imaging (perpendicular to the long axis of the tumor) through the rectal tumor and adjacent perirectal tissues. These thin-section axial images were obtained by using a 16-cm field of view, a 3-mm section thickness, no intersection gap, 4,000/85, a 256 x 256 matrix, an echo train length of eight, no fat saturation, a 32-kHz bandwidth, and four signals acquired. Image degradation due to crosstalk did not occur, as the radio-frequency pulse used in the sequence was almost square. The total examination time was 45–65 minutes, depending on the length of the tumor (range, 20–70 mm; mean, 55 mm); the majority of tumors required two acquisitions.
Specimen Handling
After total mesorectal excision, each specimen was opened along the anterior border proximal to the tumor-containing segment (the tumor itself was untouched) and fixed by total immersion in buffered formalin for 48 hours. It was then placed in a sealed polythene bag containing air and a small amount (less than 5 mL) of formalin for MR imaging. This was performed by using the same thin-section technique that was used preoperatively, with 3-mm image sections. The segment of the fixed specimen containing the tumor was then sectioned transversely at 3-mm intervals by using a sharp knife to produce tissue slices that corresponded precisely to the MR image sections.
Spatial correlation was achieved by identifying anatomic and morphologic landmarks (lymph nodes, blood vessels, and the bowel contour) visible on the specimen and the MR images of the specimen. These were in turn related to the image sections obtained from preoperative MR examination of the patient, which enabled section-for-section correlation between the in vivo MR image sections and the in vitro histopathologic slices.
Each labeled 3-mm tissue slice was pinned on a corkboard and photographed, and whole-mount or quarter-mount histopathologic slices were cut and stained with hematoxylin-eosin. The extent of local tumor spread in each histopathologic slice was then assessed according to the tumor component of the TNM system (Table 1, Fig 1) (17) and, for slices in which the tumor had penetrated the bowel wall but did not reach the lateral excision margin, the distance from the outer longitudinal muscle layer to the outermost tumor margin was measured by using a microscope stage micrometer. An overall histopathologic tumor stage for the whole tumor was also assigned, according to the maximal degree of local spread in any slice.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Statistical Methods
Interreader agreement for the MR allocation of tumor stage for whole tumors was assessed by means of the 
statistic. A P value less than .05 was considered to indicate a statistically significant difference.
Assessment of agreement between measurements of depth of extramural infiltration in tissue slices and measurements on corresponding MR sections was made by using the method comparison analysis described by Bland and Altman (16). To investigate whether specimen fixation and processing affected tumor measurements, we compared regression models of values obtained in specimen MR imaging sections against those of values obtained in preoperative MR imaging sections and in histopathologic slices.
|
RESULTS |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
Tumor Staging of Rectal Carcinoma
Histopathologic examination showed that there were five T2 tumors, 18 T3 tumors, and two T4 tumors. A further three patients had tumor present at the circumferential excision margins of a portion of the specimen, indicating incomplete excision, but no positive histologic evidence of invasion of an adjacent organ was available. Because a histopathologic stage could not be assigned with confidence in these three patients, they were not included in the tumor-staging analysis. Preoperative MR imaging led to correct prediction of the overall histopathologic tumor stage of every completely excised tumor. There was complete agreement between both readers in the assignment of the tumor stage ( = 1.0). Examples of corresponding MR sections and histopathologic slices are illustrated in Figures 3 –6.
Eleven patients had discrete extraluminal deposits that were not in continuity with the main tumor on individual MR images (Fig 5). Examination of contiguous sections showed that some of these represented extramural tongues of tumor that could be traced back to the intramural tumor in adjacent sections, but many were not. These deposits were all confirmed histologically as being composed of carcinoma. While none could be proved to be within lymph nodes, unequivocal involvement of other lymph nodes in the specimen was found in seven (64%) of the 11 patients. Only five (29%) of 17 patients without extramural deposits visible on MR images had lymph node metastases. Moreover, extramural tumor deposits were present in every patient with circumferential resection margin involvement.
Measurement of Depth of Extramural Tumor Penetration
There were 23 patients with extramural spread of tumor. An initial scattergraph plotting the measured depth of extramural spread visible on preoperative MR image sections against that in corresponding histopathologic slices suggested good agreement. Formal comparison of extramural tumor depth measured by means of MR and histopathologic examination was made on 167 triplets of corresponding preoperative MR images, specimen MR images, and tissue slices from these 23 tumors. Nineteen of the 167 had to be excluded because they corresponded to specimen MR images and tissue slices in which tumor extended to the circumferential margins, making comparison with preoperative MR images inappropriate.
Method comparison analysis (16) was performed by determining the distribution of the actual measured differences between corresponding MR and histopathologic values. A scattergraph of the differences between measured tumor depth visible on 148 preoperative MR image sections and in histopathologic slices plotted against the mean of MR and histopathologic values (Fig 7) demonstrates that individual differences ranged from -5.0 mm to +5.5 mm, with a mean of +0.13 mm, which does not differ significantly from zero (95% CI: -2.72, +2.98 mm), and a SD of 1.42 mm. The 95% CI for the mean difference suggests that the true mean difference is unlikely to be greater than 3 mm. Moreover, the scattergraph shows that there is no evidence that the differences between the two methods are greater when larger values are considered. It also shows a tight scatter of points centered on zero. Thus, there is good agreement between preoperative MR measurements and those made on the resection specimen.
|
The effect of specimen processing on measured tumor depth was investigated further by using regression models of specimen MR imaging measurements (y axis) plotted against either preoperative MR imaging measurements or histopathologic measurements (x axis), where the regression was constrained to pass through the origin. For specimen MR imaging measurements plotted against preoperative MR imaging measurements, the estimated slope is 1.04 (95% CI: 1.01, 1.08), suggesting that specimen fixation was associated with a very mild degree of tumor expansion that is unlikely to be greater than 8%. For specimen MR imaging measurements plotted against histopathologic measurements, the slope is 1.01 (95% CI: 0.98, 1.03), indicating no further effect of tissue processing.
Preoperative MR Assessment of Extramural Penetration in Incompletely Excised Specimens
In five of the 11 patients with extraluminal deposits, complete excision of the tumor at the circumferential margin was not achieved surgically. In two, the posterior mesorectal margin of the specimen was involved, and these two had the greatest measured depth of extramural invasion visible on preoperative MR images: 45 mm and 30 mm compared with a median of 6 mm and a range of 1–19 mm in the patients with posterior extramural spread in which local excision was complete. The other three patients had low rectal tumors with anterior margin involvement. Two were men in whom intraoperative biopsy findings also showed seminal vesicle invasion, and the tumors were classified for the purposes of the study as histopathologic stage T4; in these, the measured extramural tumor penetration visible on preoperative MR images was 4 mm and 5 mm compared with less than 1 mm in two men with low anterior tumors that were completely excised. The third was a woman in whom the measured extramural penetration was 14 mm. No other women had low anterior rectal tumors.
|
DISCUSSION |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
All of the patients examined in this study underwent short-course radiation therapy 1 week before surgery. This resulted in no discernible histopathologic evidence of a radiation therapy effect on the tumors. In particular, there was no evidence of florid inflammation or fibrosis. Accordingly, we consider that this treatment had no material effect on our results.
In previous studies (19–22), particularly those in which endoluminal US was used, a peritumoral reaction, comprising fibrosis and inflammation, was described as an important cause of overstaging. In one large study (20), two-thirds of staging errors were due to overstaging of T2 tumors, mainly as a result of extramural fibrosis at the advancing edge of the tumor. In our experience with using MR, this has not been a problem, because we consider that peritumoral fibrosis has a distinct MR appearance that can be distinguished from the tumor itself. Fibrosis has a lower signal intensity and is spiculated (Fig 6), as opposed to the broad-based pushing or nodular configuration of an advancing tumor margin (Fig 5). An inflammatory reaction at the growing tumor margin, along the contour of the tumor itself, occurs in about 25% of rectal cancers (23), but this is usually on the order of micrometers rather than millimeters in thickness (24), which is insufficient to result in substantial overstaging.
It is important to stress that we based an MR diagnosis of T3 lesions on the presence of tumor signal intensity extending into the perirectal fat signal intensity with a broad-based bulging configuration and in continuity with the intramural portion of the tumor. Irregularity and disruption of the outer longitudinal muscle alone were not enough: Interruptions of the outer contour of the muscle coat of the rectum occur normally as a result of small vessels penetrating the wall (Fig 3), and the longitudinal muscle layer itself often has an irregular corrugated appearance in the absence of tumor.
Our experience in this study was that MR consistently helped distinguish between T2 and T3 tumors. However, we must concede that the number of patients with T2 tumors studied was small, although it represents experience with a consecutive series at our institution. We know from the discrepancies between our measurements on individual sections (mean difference, 0.13 mm; range, -5.0 to +5.5 mm) that MR has the potential to result in overstaging or understaging borderline T3-T2 tumors, as noted by others who used an endorectal coil (14). However, differentiating between minimal T3 infiltration and T2 lesions is probably of relatively little consequence for patient treatment, as patients with minimal T3 infiltration into perirectal fat are at low risk of surgical failure from circumferential excision margin involvement (1,25). Consequently, we argue that, except possibly for low rectal tumors, patients with minimal T3 involvement may not require preoperative radiation therapy.
Our observation that MR imaging can provide accurate information on the extramural spread of rectal cancer, not only on its precise anatomic position but also on the depth of penetration beyond the muscle coat, is likely to be of considerable value in the management of this condition. It will allow better selection of patients for preoperative radiation therapy, facilitate the planning of how that radiation therapy is directed, and provide the surgeon with useful additional information before embarking on the surgical procedure.
Indeed, it is likely that if the accuracy of preoperative MR imaging measurement of extramural spread had been appreciated, surgical difficulty in achieving clearance of the five tumors that were incompletely excised in this study could have been predicted and greater consideration given to the use of a 4-week preoperative course of high-dose radiation therapy instead of the short-course treatment that was used. On the other hand, reliable preoperative assessment of tumor depth should also help to identify T3 tumors in patients in whom adjuvant therapy would not offer an advantage, such as those with minimally invasive T3 tumors and T2 lesions. Our results offer promise for thin-section MR imaging as a means of making this distinction.
To our knowledge, our study is the first to investigate formally the accuracy of MR imaging in measuring the depth of extramural spread by using meticulous comparisons of in vivo MR images and MR images of histopathologic specimens to validate the measurements. Because fixation and processing of histopathologic specimens are widely considered to lead to tissue shrinkage and distortion, we performed MR imaging on the specimens to improve the reliability of our comparisons and to facilitate the matching of preoperative MR sections with their histopathologic counterparts. No apparent distortion occurred during fixation because the specimen was fixed intact, and the shape of both the rectum and mesorectum was retained.
Moreover, our careful statistical analysis indicated that specimen fixation and processing did not lead to any significant (95% CI: 1.01, 1.08) reduction of tumor thickness. Indeed, there is a suggestion that specimen fixation and processing may lead to a minor degree of tumor expansion, by up to 8%. We consider this small change of no importance in the interpretation of our results. It is likely, therefore, that different tissue types change in different ways in response to fixation. It is of note that another recent study (26) of the effect of fixation on prostatic tissue volumes also showed relatively little change.
We did not attempt to undertake lymph node staging by means of MR imaging in this study because we have strong reservations about the reliability of imaging modalities for predicting lymph node involvement. Most attempts to assess this have used the short-axis diameter of the node to define lymph node involvement, but the high frequency of enlarged reactive lymph nodes adjacent to rectal cancers and of small lymph nodes that contain metastasis both restrict imaging accuracy greatly (22,27). It is, therefore, unlikely that any currently available imaging modality can be used reliably to identify lymph node involvement.
However, we found that preoperative identification of extraluminal deposits (defined as discrete but irregular nodular masses in the perirectal fat with the same signal intensity and morphology as the intraluminal tumor) on MR images appears to be reliable, and our preliminary data suggest that their presence may indicate a poor prognosis subgroup for consideration of preoperative adjuvant therapy. We do not know whether these extramural deposits represent completely replaced lymph nodes or simply mesorectal metastases. They occurred in all five tumors that were incompletely excised by means of total mesorectal excision, and concurrent histologically proved lymph node metastasis was present in seven (64%) of the 11 patients with extramural deposits compared with only five (29%) of the 17 patients without extraluminal deposits. Whether these extramural tumor deposits represent completely replaced lymph nodes or simply represent mesorectal metastases is not clear, but the distinction has no effect on TNM staging, which would categorize all 11 cases as having nodal metastases.
The MR imaging technique we describe compares favorably with endoluminal US for staging rectal cancer in a number of respects. First, it can be used in all patients, irrespective of the size or location of the tumor. Second, it can equal, or even surpass, the accuracy of endoluminal US in those patients who can be examined because of its relatively large field of view compared with the inherently small field of view associated with endoluminal US (or endorectal MR). Third, it overcomes the major limitation of endoluminal US in the evaluation of polypoid, bulky, or fungating tumors in which the probe has to be placed tangential to rather than perpendicular to the tumor, resulting in difficulties in interpretation of the depth of tumor invasion (22). Fourth, it allows peritumoral fibrosis to be distinguished from tumor infiltration, and it accurately depicts tumors with extensive extramural spread. Finally, it allows demonstration of the relationship of the tumor to the mesorectal fascia, which is in the plane through which total mesorectal excision is usually performed.
The success of the MR imaging technique we describe contrasts with the disappointing results of previous staging attempts in which body-coil MR imaging was used; these disappointing results have been attributed to the use of thick sections and large fields of view that result in low-spatial-resolution images that fail to resolve the layers of the rectal wall (28–31). We think that our much improved results with a surface coil are due not only to thinner sections with higher-spatial-resolution parameters but also to the careful attention paid to ensuring that the images are acquired as true axial images of the tumor itself, rather than of the pelvis as a whole. This reduces overestimation of depth from oblique imaging. We believe the benefits obtained in accuracy are well worth the small increase in imaging time.
In conclusion, thin-section MR imaging of the pelvis by using the four-element surface coil and axial images of the tumor enables noninvasive, accurate, preoperative assessment of the stage and depth of extramural tumor infiltration in rectal cancer. We suggest that information obtained in this way be used to decide the best primary treatment in all patients with the disease.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
|
References |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  S. H. Kim, J. M. Lee, M. W. Lee, G. H. Kim, J. K. Han, and B. I. Choi Sonography Transmission Gel as Endorectal Contrast Agent for Tumor Visualization in Rectal Cancer Am. J. Roentgenol., July 1, 2008; 191(1): 186 - 189. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. M. Zhang, H. L. Zhang, D. Yu, Y. Dai, D. Bi, M. R. Prince, and C. Li 3-T MRI of Rectal Carcinoma: Preoperative Diagnosis, Staging, and Planning of Sphincter-Sparing Surgery Am. J. Roentgenol., May 1, 2008; 190(5): 1271 - 1278. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. G. Guillem, J. A. Diaz-Gonzalez, B. D. Minsky, V. Valentini, S.-Y. Jeong, M. A. Rodriguez-Bigas, C. Coco, R. Leon, J. L. Hernandez-Lizoain, J. J. Aristu, et al. cT3N0 Rectal Cancer: Potential Overtreatment With Preoperative Chemoradiotherapy Is Warranted J. Clin. Oncol., January 20, 2008; 26(3): 368 - 373. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. R. Muthusamy and K. J. Chang Optimal Methods for Staging Rectal Cancer Clin. Cancer Res., November 15, 2007; 13(22): 6877s - 6884s. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S D Allen, V Gada, and D M Blunt Variation of mesorectal volume with abdominal fat volume in patients with rectal carcinoma: assessment with MRI Br. J. Radiol., April 1, 2007; 80(952): 242 - 247. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 MERCURY Study Group Extramural Depth of Tumor Invasion at Thin-Section MR in Patients with Rectal Cancer: Results of the MERCURY Study Radiology, April 1, 2007; 243(1): 132 - 139. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. D. Allen, A. R. Padhani, A. S. Dzik-Jurasz, and R. Glynne-Jones Rectal Carcinoma: MRI with Histologic Correlation Before and After Chemoradiation Therapy Am. J. Roentgenol., February 1, 2007; 188(2): 442 - 451. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Akasu, T. Yamaguchi, Y. Fujimoto, S. Ishiguro, S. Yamamoto, S. Fujita, and Y. Moriya Abdominal Sacral Resection for Posterior Pelvic Recurrence of Rectal Carcinoma: Analyses of Prognostic Factors and Recurrence Patterns Ann. Surg. Oncol., January 1, 2007; 14(1): 74 - 83. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H.-K. Chun, D. Choi, M. J. Kim, J. Lee, S. H. Yun, S. H. Kim, S. J. Lee, and C. K. Kim Preoperative staging of rectal cancer: comparison of 3-T high-field MRI and endorectal sonography. Am. J. Roentgenol., December 1, 2006; 187(6): 1557 - 1562. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 MERCURY Study Group Diagnostic accuracy of preoperative magnetic resonance imaging in predicting curative resection of rectal cancer: prospective observational study BMJ, October 14, 2006; 333(7572): 779. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. C. Stollfuss, K. Becker, A. Sendler, S. Seidl, M. Settles, F. Auer, A. Beer, E. J. Rummeny, and K. Woertler Rectal Carcinoma: High-Spatial-Resolution MR Imaging and T2 Quantification in Rectal Cancer Specimens Radiology, October 1, 2006; 241(1): 132 - 141. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Iafrate, A. Laghi, P. Paolantonio, M. Rengo, P. Mercantini, M. Ferri, V. Ziparo, and R. Passariello Preoperative staging of rectal cancer with MR Imaging: correlation with surgical and histopathologic findings. RadioGraphics, May 1, 2006; 26(3): 701 - 714. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Chau, G. Brown, D. Cunningham, D. Tait, A. Wotherspoon, A. R. Norman, N. Tebbutt, M. Hill, P. J. Ross, A. Massey, et al. Neoadjuvant Capecitabine and Oxaliplatin Followed by Synchronous Chemoradiation and Total Mesorectal Excision in Magnetic Resonance Imaging-Defined Poor-Risk Rectal Cancer J. Clin. Oncol., February 1, 2006; 24(4): 668 - 674. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A S K Dzik-Jurasz Pelvic malignancy: integrating form and function Br. J. Radiol., October 1, 2005; 78(Special_Issue_2): S86 - S93. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R J Heald Surgical management of rectal cancer: a multidisciplinary approach to technical and technological advances Br. J. Radiol., October 1, 2005; 78(Special_Issue_2): S128 - S130. [Full Text] [PDF]
|
