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At least 19 recordsLinked to original sources

PubMed1999

Dose-wall histograms and normalized dose-surface histograms for the rectum: a new method to analyze the dose distribution over the rectum in conformal radiotherapy.

PURPOSE: To develop an accurate method to generate a dose-volume histogram (DVH) of the rectum wall, solely based on the outer contours of the rectum wall. METHODS AND MATERIALS: A mathematical model for the rectum wall is developed, incorporating the stretching of the rectum wall due to variable rectal filling and neighboring structures. The model is based on the assumption that the amount of intersected rectum wall tissue normal to the central axis of the rectum is constant. The main objective of the model is to determine the thickness of the rectum wall in each wall element. Two approaches are described, each yielding a DVH of the rectum wall, based only on the delineated outer contours of the rectum. In the first approach, the model is used to create a set of inner contours out of the axial outer contours. Both sets of contours are used to derive a dose-wall histogram (DWH) of the rectum. In the second approach, the model is used to generate a normalized 2D sampling space, which is subsequently binned into a normalized dose-surface histogram (NDSH). The model is verified using 20 sets of CT data (5 patients x 4 scans) in which both outer and inner contours of the rectum are carefully delineated. The DWHs and NDSHs are compared with DVHs of the rectum wall, which require contouring of the outer and inner surfaces of the rectum wall, and with DVHs of the total rectum (including rectal filling). The variation between DWHs, NDSHs, and DVHs is investigated using normal tissue complication probability (NTCP) calculations. RESULTS: The local wall thickness of the rectum as outlined on CT data was in conformity with the described rectum model. The amount of rectum wall tissue per unit length rectum varied considerably between patients (27%, 1 SD). In all analyzed patients, the DWHs and NDSHs corresponded well to the DVHs of the rectum wall. Much more discrepancies were observed between the DVHs of the total rectum and the DVHs of the rectum wall. CONCLUSION: The applied methods yield accurate dose distributions of the rectum wall, without delineating the inner surface of the rectum. This reduces both the workload and variations due to inaccurate delineation of the rectum wall. The DWH and NDSH are effective tools to evaluate 3D dose distributions of the rectum wall and to estimate the complication probability of the rectum in high-dose conformal radiotherapy.

Humans↗

PubMed2002

Rectum contouring variability in patients treated for prostate cancer: impact on rectum dose-volume histograms and normal tissue complication probability.

BACKGROUND: Recent investigations showed some correlation between three-dimensional (3D) treatment planning dose-volume data (dose-volume histograms: DVH, dose statistics) and rectal toxicity for patients treated for prostate cancer. However, no data are available about the possible impact of inter-institute variability in contouring the rectum, so that the possibility of reliably using information from single-centre studies remains doubtful. PURPOSE: Within a retrospective three-institutes study on correlation between dose-volume treatment planning data and rectum bleeding in patients treated for prostate cancer, an investigation about the impact of inter- and intra-observer variability in contouring the rectum was performed. MATERIALS AND METHODS: Ten patients were considered for a dummy run exercise and three observers (one per Institute) contoured the rectum (including filling). An anatomically based definition of rectum extension was previously accepted by the three observers. Six of the ten patients were randomly chosen in the subgroup of patients (large spacing, LS) with a distance between computed tomography (CT) slices (outside the prostate region) equal to 10 mm; for the remaining four patients the distance between CT slices was 5 mm over the whole rectum volume (small spacing, SS). The original 3D treatment planning was recovered on the Cadplan treatment planning system for each patient and rectum dose statistics (mean, median and maximum rectum dose), volume, DVH and NTCP values were calculated for each observer. For DVH analysis, the values of V(50), V(55), V(60), V(65) and V(70) (defined as the % of rectum volume receiving at least 50, 55, 60, 65, 70 Gy) were considered. Normal tissue complication probabilities (NTCPs) were calculated for the original ICRU dose and for a 75.6 Gy ICRU dose (NTCP and NTCP(75.6), respectively). Intra-observer variability was investigated by asking the observers to redraw the same rectum contours 6 months later and comparing the two contouring sessions. RESULTS: In general, a good agreement was found for most patients and, in particular, for all SS patients. The impact of inter-observer variability was quite significant on dose statistics and DVH in two of six LS patients. Looking at the patient population, some systematic deviations, even if quite small, were demonstrated between institute B and institute C (volume, P = 0.02) and between institute A and institute B (mean/median dose, V(50)-V(65), NTCP(75.6); P < 0.05). Four of six LS patients (0/4 in the SS group) presented a maximum difference among observers at the cranial and/or caudal limit of the rectum equal to 1 cm. For these patients, inter-observer variability was significantly higher than for the others (P < 0.03). When inter-observer variability was expressed in terms of standard deviations (SD), values around 2-3 Gy and 0.5 Gy for LS and SS patients, respectively, were found for mean/median dose; values around 3-4% and 0.5-2% for LS and SS patients, respectively, were found for V(50)-V(70). The average SD for NTCP and NTCP(75.6) were 0.4 and 0.6%, respectively (0.5 and 0.9% for LS patients; 0.2 and 0.3% for SS patients). Intra-observer variability was found to be lower than inter-observer variability even if the impact on dose statistics and DVH was visible. CONCLUSIONS: Once a robust definition of rectum is assessed, inter- and intra-institute variability in contouring the rectum appear relatively modest. However, the results suggest that the number of LS patients in DVH correlation studies should be as low as possible; the low number of these patients in the multi-centric trial involving our institutions should not have significant impact on the results of the study.

Hemorrhage↗

PubMed2003

Bladder and rectum dose defined from MRI based treatment planning for cervix cancer brachytherapy: comparison of dose-volume histograms for organ contours and organ wall, comparison with ICRU rectum and bladder reference point.

PURPOSE: To analyze the correlation between dose-volume histograms based on organ contour and organ wall delineation for bladder and rectum, and to compare the doses to these organs with the absorbed doses at the ICRU bladder and rectum reference points. MATERIAL AND METHODS: Individual MRI based brachytherapy treatment planning was performed in 15 patients as part of a prospective comparative trial. The external contours and the organ walls were delineated for the bladder and rectum in order to compute the corresponding dose-volume histograms. The minimum dose in 2 cm(3), 5 cm(3) and 10 cm(3) volumes receiving the highest dose were referred to as [D2], [D5] and [D10] and compared with the absorbed dose at the ICRU rectum and bladder reference point. RESULTS: The bladder (bext) and rectal (rext) doses derived from external contours and computed for volumes of 2 cm(3) [D2], provided a good estimate for the doses computed for the organ walls (bw and rw) only (mean ratio [D2](bext)/[D2](bw)=1.1+/-0.2 and [D2](rext)/[D2](rw)=1.2+/-0.1, respectively). This correspondence was no longer true when larger volumes were considered (5 and 10 cm(3)). The dose at the ICRU rectum reference point did overestimate the dose computed for 2 cm(3) of the rectum wall (mean ratio: 1.5+/-0.4). In contrast, the dose at the ICRU bladder reference point did-in the case of inappropriate topographic location of the balloon-underestimate the dose computed for 2 cm(3) of the bladder wall (overall mean ratio: 0.9+/-0.4). CONCLUSION: For clinical applications, when volumes smaller than 5 cm(3) are considered, the dose-volume histograms computed from external organ contours for the bladder and rectum can be used instead of dose-volume histograms computed for the organ walls only. External organ contours are indeed easier to obtain. The dose at the ICRU rectum reference point provides a good estimate of the rectal dose computed for volumes smaller than 2 cm(3) [D2] only for a midline position of the rectum. The ICRU bladder reference point provides a good estimate of the dose computed for the bladder wall [D2] only in cases of appropriate balloon position.

Adenocarcinoma↗

PubMed2002

[Initial empirical antimicrobial therapy with piperacillin/tazobactam in intra-abdominal infections due to perforation of the large intestine and rectum and in postoperative complications after resection of the large intestine and rectum].

One of the basic therapeutic procedures in surgical intraabdominal infections is early administration of antimicrobial drugs. The basic requirement for the selection of antimicrobial drugs is a broad-spectum bactericide action with low toxicity. Within the framework of a retrospective non-comparative investigation the action of the betalactam antibiotic piperacillin combined with the betalactamase inhibitor tazobactam was tested which was used in the initial empirical antimicrobial treatment of 33 patients with intraabdominal infectious complications caused by perforation of the large bowel or dehiscence of the anastomosis on the large intestine or rectum. Twenty-eight patients developed diffuse inflammation of the peritoneum (caused by perforation of a diverticulum in 17, by dehiscence of the anastomosis on the large intestine and rectum after resection on account of carcinoma in 7, by a penetrating injury of the large bowel and rectum in 3 and by postirradiation necrosis of the rectum in one female patient). Five patients developed an intraabdominal abscess as a complication of diverticulitis of the large intestine or as a postoperative infectious complication after resection of the large bowel and rectum. All patients were operated (resection of the large bowel according to Hartmann, or stoma above the site of injury or dehiscence of the intestinal anastomosis or drainage of the abscess). After surgery administration of piperacillin/tazobactam (4.5 g, subsequently after 8 hours). The period of administration was on average 8 days (5 to 11 days). After surgery the contents of the peritoneal cavity were collected for bacteriological examination incl. evaluation of the sensitivity of the isolated bacteria to piperacillin/tazebactam. From the isolated pathogens 58% were Gram-negative aerobic bacteria, in 24% anaerobic bacteria and in 18% enterococci. In 3 patients antimicrobial treatment was because of resistance of isolated bacteria to piperacillin/tazobactam (Klebsiella species, Pseudomonas aeruginosa) combined with aminoglycosides (amikacin, netilmicin). Postoperative complications developed in 9 patients (27%), incl. 3 who died (9%). In patients with intraabdominal infection caused by perforation of the large bowel and rectum or dehiscence of the anastomosis after resection of the large bowel and rectum piperacillin/tazobactam is the antibiotic of choice for the initial empirical antimicrobial treatment on account of its great efficacy against the majority of isolated bacteria, its safety and low toxicity.

Abdominal Abscess↗

PubMedDate not supplied

[Rectum diverticulum/perineal hernia surgery through longitudinal contracting of the wall of the rectum].

Older male dogs often exhibit the symptoms of rectum diverticulum and perineal hernia. In order to point out the often common reason of these disorders, the term "rectum diverticulum/perineal hernia complex" has been introduced. In a large group of such patients two methods of surgical correction of this problem were retrospectively evaluated. Only patients were included in this evaluation that were euthanized if recurrence occurred. In 21 patients (group 1) the often performed method of Bojrab was used, both in rectum diverticulum and in perineal hernia operations. In group 2 15 dogs were subjected to the same operation technique, but we performed an additional pleating contraction of the herniated gut wall layers. In case of visible recurrence at an age of at least 11 years the dogs were euthanized. Group 1 showed a postoperative survival time of 3.61 +/- 0.96 years until recurrence, group 2 revealed recurrence not before 4.93 +/- 0.93 years post operationem. The difference is significant (p < 0.05). It is the opinion of the authors that additional longitudinal contracting by pleating of the gut markedly prolonges the point of time when recurrence appears.

Animals↗

PubMed1998

[Anterior rectum resection and abdominoperineal rectum excision: guidelines for decision making].

Carcinomae of the upper third of the rectum are, almost without exception, and without loss of continence, resectable. The diagnosis of an intact sphincter function is significant in the pre-operative phase, when deciding whether to carry out an anterior rectum resection or an abdominoperineal rectum exstirpation. Concerning tumours as from G3 in the middle and distal thirds, a safety margin of at least 5 cm distal must be kept, thus making an anterior resection impossible. Stage IV tumours whose growth has infiltrated neighbouring organs or the pelvic wall are also not suitable for resection. Should anatomical circumstances such as excessive adipositae, very large carcinomae, narrow pelvis and enlargement of the uterus or prostata prevent the safe dissection of the mesorectum a sphincter-retaining operation is also not indicated. Oncologic safety is of the highest priority when considering such cases.

Abdomen↗

PubMed1986

Resection of the rectum with construction of a colonic reservoir and colo-anal anastomosis for carcinoma of the rectum.

Rectal resection with colo-anal anastomosis was performed in 65 patients with carcinoma of the lower rectum. In 20 a pelvic colonic reservoir was constructed while in 45 a direct anastomosis was carried out. There were no postoperative deaths and morbidity was comparable in the two groups. Functional results were determined by clinical examination and manometry. The frequency of bowel movements was inversely related to the maximum tolerated volume (P less than 0.001). During the first year 60 per cent of the patients with a reservoir and 33 per cent of the patients without had one or two stools per day (P less than 0.05). After one year, 86 per cent of the patients with a reservoir and 33 per cent of the patients without had one or two bowel movements per day (P less than 0.01). The maximum tolerated volume was increased by the reservoir (P less than 0.05). The loss of reservoir capacity of the rectum increases frequency of bowel movements in colo-anal anastomosis. The creation of a colonic reservoir improves function by increasing the maximum tolerated volume without any increase in mortality or morbidity.

Adult↗

PubMed1997

[Results of deep rectum resection and intersphincteric rectum excision].

Low resection and intersphincteric extirpation of rectal cancer in the distal third of the rectum has become an accepted sphincter-saving method. From December 1990 to December 1994, 42 patients (17 women and 25 men) with a mean age of 67.2 years had a low resection or extirpation of the rectum at our institution. Eighteen patients received a transanal sutured anastomosis, 24 a stapler anastomosis. We had a lethality rate of 2.5% and a anastomotic insufficiency rate of 14%.

Aged↗

PubMedDate not supplied

Late heat damage in normal swine rectum: a comparison of thermosensitivity of rectum and oesophagus.

The normal swine rectum was heated using an intracavitary microwave radiator for 30 min at 43, 44, 45, 46, 47, and 48 degrees C. The animals were sacrificed 30 days later. The degree of heat injury was evaluated on a histological score system with a maximum possible damage score of 36 (100%). The scores for late damage were 8, 21, 23, 54, 58, and 74%, respectively. The 50% maximum damage was 45.8 +/- 0.5 degrees C/30 min. With the same score system, the heat damage to the oesophagus, which we have calculated previously, was evaluated and compared with that of the present data. The heat damage at the same temperature applied to the lumen was more severe in the rectum than that of the oesophagus. There was a roughly 2-3 degrees C difference in thermosensitivity between these two organs.

Animals↗

PubMed1994

Coordinated activity of the new "rectum" and anal sphincter after sphincter-saving resection of the rectum for colitis or carcinoma.

PURPOSE: The aim of this study was to determine whether coordinated activity exists across a stapled enteroanal anastomosis. METHODS: Twenty-nine patients were studied for a median of one year after complete excision of the rectum and stapled enteroanal anastomosis; 12 patients underwent low anterior resection with coloanal anastomosis for carcinoma, and 17 patients underwent restorative proctocolectomy with ileoanal anastomosis. RESULTS: Maximum anal resting pressures were slightly lower after coloanal anastomosis than after ileoanal anastomosis [median range, 56 (11-60) cm H2O, cf 69 (40-107) cm H2O, P = NS]. During distention of the neorectum, anal sphincter pressures at 2.5, 1.5, and 0.5 cm from the anal verge were significantly lower after coloanal anastomosis compared with after ileoanal anastomosis (P < 0.01 at each station). The volume of neorectal distention required to produce maximal inhibition of the anal sphincter was significantly less after coloanal anastomosis at 50 (range, 20-60) ml of air than after ileoanal anastomosis at 240 (range, 100-420) ml of air (P < 0.01). Minor fecal leakage and urgency of bowel action were significantly more common after coloanal anastomosis (P < 0.01). CONCLUSION: Alterations in the dynamic response of the anal sphincter to distention of the neorectum may explain why the clinical results were better after ileal pouch-anal anastomosis than after coloanal anastomosis.

Adult↗

PubMed1989

[Low anterior resection of the rectum with the linear and circular stapler in the treatment of carcinoma of the middle third of the rectum].

Low anterior resection by linear (TA 55) and circular (EEA) stapler was done in eighteen patients with adenocarcinoma of the middle third of the rectum. One patient died of lung embolism after having underwent the surgery. The stercoral fistula was clinically and radiologically proven in only one of the surgically treated patients and it healed without medicament therapy. The protective proximal colostomy was not performed. Late functional results were satisfactory and none of the patients developed stenosis of the anastomosis. Two operated patients (Dukes' C) relapsed 12 and 18 months after the surgery.

Adenocarcinoma↗

PubMed1984

[Technic of rectum anastomoses in rectum resection. A controlled study: instrumental suture versus hand suture].

Stapler and manual sutures in rectal end-to-end anastomoses were compared in a controlled trial. The following results were obtained: For the analysis the cases naturally separated into three groups, A (manual suture), B (planned stapler suture) and WD ("withdrawn" cases, from both groups, in which continence could be maintained only with a stapler suture). The distribution of the WD cases in dependence on localization and sex varied significantly from groups A and B, while A and B remained comparable, in spite of the WD cases. The analysis of the date showed no, or only slight, clinical differences. In a comparison of the two stapler groups B and WD, significantly more suture dehiscences, colocutaneous fistulae and post-operative disturbances in bladder function were found in group WD. As a general conclusion we can state that: In comparable anastomosis localizations it is possible to achieve almost the same clinical results with both suture techniques. With a circular stapler it is, however, technically possible to perform rectum resections in cases in which this was not previously possible, particularly in men with a narrow pelvis and a stale pelvic floor. To what extent this still is an advantage after the local recurrences are taken into consideration remains to be seen.

Clinical Trials as Topic↗

PubMed1981

[Rectum extirpation or rectum resection in rectal cancer?].

Rate of recurrences and morbidity of anterior resection and abdomino-perineal extirpation in cancer of the rectum and especially of the midrectum are correlated to tumor localization, -staging and -grading. Regarding stage of the tumor both surgical procedures are equivalent. Poorer prognosis after abdomino-perineal extirpation is mainly due to advanced tumor stage. In cancer of the midrectum anterior resection should be performed.

Humans↗

PubMed1992

[Leiomyosarcomas of the rectum. Amputation of the rectum or local resection?].

Two cases of high grade leiomyosarcoma of the rectum treated by local excision are reported. The first patient presented a local recurrence associated with liver and pulmonary metastases and eventually died, respectively 11 and 22 months after resection. The second patient's tumor recurred 3 months after excision and was treated with pelvic exenteration and CYVADIC regimen as chemotherapy and died 3 years later from local recurrence. A review of the literature indicates that local surgical excision in comparison to a more radical surgical approach, such as abdominoperineal resection, is as effective in improving survival. Lesions less than 2.5 cm in diameter, confined to the bowel can be treated by local surgical excision. To date no adjuvant therapy is effective in terms of survival or local control.

Female↗

PubMed1956