CT of the mesocolon. Part 2. Pathologic considerations.

The anatomy of the mesocolon can be seen on computed tomographic (CT) scans, and its CT anatomy can be described by using the vessels in the mesocolon as anatomic landmarks. Knowledge of this anatomy is the basis to understanding pathologic processes involving the mesocolon. Common pathologic conditions usually occur due to spread of disease between organs to which the mesocolon is attached, primarily the colon and pancreas. The disease may be a malignant lesion, a benign inflammatory process, or, rarely, a primary tumor of the mesocolon; the mode of spread may be via the lymphatic vessels, direct extension, vascular invasion, or vascular involvement. The authors demonstrate various pathologic conditions and modes of spread, as seen on CT scans, with emphasis on disease of the colon and pancreas. The pathway for the spread of disease and its progression in these organs can be predicted in patients with a known disease. More important, identification of abnormalities in the mesocolon leads to careful evaluation of the organs to which the mesocolon is attached.

CT of the mesocolon. Part 1. Anatomic considerations.

To define the anatomy of the mesocolic attachment of the colon as seen on computed tomographic (CT) scans, the authors reviewed CT scans of patients with diseases of the colon and the pancreas and found that disease processes in these areas usually spread along the mesocolon. The plane of the mesocolon can be distinguished from the mesentery of the small bowel by identifying the vessels in the mesocolon that serve as its landmarks. These vessels include the ileocolic vessels and right colic vessels for the ascending mesocolon, the middle colic vessels for the transverse mesocolon, and the inferior mesenteric vein for the sigmoid and descending mesocolon. These vessels can be seen routinely on CT scans of the abdomen and pelvis, and knowledge of the anatomy of the mesocolon can help the radiologist understand and identify the pathways for spread of diseases of the colon and pancreas. Recognition of the anatomy of the mesocolon is also helpful in the identification of the pattern of recurrent disease after treatment.

Metastases to the pancreas and peripancreatic lymph nodes from carcinoma of the right side of the colon: CT findings in 12 patients.

OBJECTIVE: Our objective was to describe the CT findings of metastases to the pancreas from carcinoma of the colon and to discuss the pathways of metastasis based on the anatomic relationship between the mesocolon and the pancreas. MATERIALS AND METHODS: Clinical features and CT scans of 12 patients who had proved metastases to the pancreas from adenocarcinoma of the colon were retrospectively reviewed to define the characteristics of pancreatic lesions. The primary tumors were in the cecum (three patients), ascending colon (five patients), and transverse colon (four patients). Direct extension of the tumor to the pancreas was excluded. Metastases were diagnosed by aspiration or surgical biopsy. RESULTS: Seven patients (58%) had obstruction of the bile duct and/or pancreatic duct. Four others had symptoms related to the mass, including pain and gastrointestinal obstruction. In eight patients (67%), metastatic tumors involved the pancreas as a focal mass; in the other four (33%), the masses were lobulated and engulfed the pancreas and were indistinguishable from peripancreatic nodal disease. The masses were hypodense in nine patients (75%) and isodense in three patients (25%). Extra-pancreatic metastatic disease was seen in nine patients (75%). CONCLUSION: Clinical features and CT findings in patients with pancreatic metastases from carcinoma of the colon are similar to those of primary pancreatic ductal adenocarcinomas. The diagnosis of metastasis should be considered when a patient has a pancreatic mass and a history of colon carcinoma.

Regional lymph node metastases in carcinoma of the left side of the colon and rectum: CT demonstration.

The distribution of regional lymph node metastases in carcinoma of the left side of the colon, rectum, and anus can be well shown by routine CT of the abdomen and pelvis. Recognition of the location of nodes in the mesocolic, left colic, and IMA nodal groups can help in developing a systematic approach to the detection of nodal metastasis. This can be especially important in preoperative planning for cases in which resection may be curative. In addition, an understanding of the distribution of nodal metastasis will make it possible to recognize early recurrent nodal disease, particularly with an increase in associated increase in levels of carcinoembryonic antigen, and to predict certain clinical sequences such as hydronephrosis of the left kidney associated with left colic nodal metastases.

An aid to image interpretation and differential diagnosis.

RATIONALE AND OBJECTIVES: Proven case conference is a weekly 1-hour session designed to aid diagnostic radiology residents in their ability to interpret images and formulate differential diagnoses. This article provides a detailed description of the format of this conference and its use in evaluating resident performance. METHODS: The scores of all residents on the written portion of this conference over a 2-year period were compiled. Results were divided according to each residency class, and each resident was compared with the mean of his or her class and with previous performance. RESULTS: There was overall improvement of the group over the course of residency. All individual scores showed improvement during the 2-year period studied. CONCLUSION: Proven case conference is a simply performed, well-accepted aid to image interpretation and differential diagnosis. It affords residents an ongoing opportunity for practical learning and provides the residency program director with an objective tool for resident evaluation.

Case report 660: Adamantinoma of tibia.

An adamantinoma of the tibia is presented, for which the CT and MRI characteristics are described. Both imaging modalities were excellent in providing information as to the extent and invasiveness of the tumor, although MRI had the advantage of providing immediate high quality sagittal visualization. Comparison is made briefly between adamantinoma and both fibrous dysplasia and osteofibrous dysplasia.

Tumor volume and treatment outcome in small cell lung carcinoma.

The volume of some tumors correlates with local disease control, response, and survival. Small cell lung carcinoma presents with variable and often large intrathoracic masses. We assessed volume by two methods (summation of cross-sectional areas and Simpson's rule for estimating volume) and correlated volume with treatment outcome. Twenty-nine patients with small cell lung carcinoma (12 limited disease and 17 extensive disease) were analyzed for volume outcome correlations. There were five early deaths. Twenty-four had response correlations (11 limited disease and 13 extensive disease). Eighteen of the twenty-four achieved complete response. There was no apparent correlation between complete and/or partial response and pretreatment tumor volume. There was no apparent correlation between survival and volume. The methods of volume assessment correlate well with each other (r = 0.88) and either can be used with accuracy. So far there is also no correlation between chest tumor volume and intrathoracic recurrence. Our projections suggest that there is a low probability of correlating chest tumor volume and either response or survival. This is in keeping with the disseminated nature of the tumor which is its limiting factor in survival.

Blunt hepatic trauma in adults: CT-based classification and correlation with prognosis and treatment.

To further define the computed tomographic (CT) criteria on which to guide the nonsurgical treatment of adult patients with blunt hepatic injury, the authors retrospectively reviewed abdominal CT scans obtained before surgery during a 35-month period. Blunt hepatic injury was diagnosed in 187 patients, and review revealed 37 patients in whom the liver was the site of sole or principal intraabdominal injury detected with the help of CT before surgery. A CT-based hepatic injury classification system partly derived from similar systems established with surgical assessment was devised to grade the severity of hepatic injury. CT-based injury scores ranging from grade 1 to 5 were compared with the clinical outcome in patients treated surgically and nonsurgically. Thirty-one patients (83.7%) were successfully treated without surgery, and four patients (10.8%) had findings at celiotomy that did not require further surgery. No patient who was initially treated without surgery required delayed celiotomy due to hepatic injury. The results indicate that even major hepatic injury up to and including grade 4 severity assessed with preoperative CT can usually be managed without surgery in hemodynamically stable patients.

Blunt splenic trauma in adults: CT-based classification and correlation with prognosis and treatment.

Nonsurgical management of blunt splenic injury in children is a well-established method to salvage splenic function; however, nonsurgical management of adult blunt splenic trauma remains controversial. To assess the value of preoperative abdominal CT in predicting the outcome of blunt splenic injury in adults, a CT-based injury-severity score consisting of four grades was devised and applied in 39 adult patients with blunt splenic injury as the sole or predominant intraperitoneal injury detected with preoperative CT. While patients with high grades of splenic injury generally required early surgery, eight (35%) of 23 patients with initial grade 3 or 4 injury were treated successfully without surgery, and four (29%) of 15 patients with grade 1 or 2 injury initially treated nonsurgically required delayed celiotomy (n = 3) or emergency rehospitalization. Results show that while CT remains an accurate method of identifying and quantifying initial splenic injury, as well as documenting progression or healing of critical injury, CT cannot reliably help predict the outcome of blunt splenic injury in adults. Treatment choices should therefore be based on the hemodynamic status of the patient and results of serial laboratory and bedside assessments.

Tamoxifen withdrawal response. Report of a case.

A postmenopausal patient with breast cancer with a left infrahilar lung mass was treated with tamoxifen. She became asymptomatic, but after having stable disease for eight months, she developed progressive increase in the size of the mass necessitating tamoxifen withdrawal. Complete resolution of the mass occurred following withdrawal of tamoxifen. Withdrawal responses, though known to occur with additive hormonal treatment, especially complete regression of metastatic disease as seen in our patient, is not widely recognized. Thus, when clinically possible, patients should be observed off treatment for up to six weeks, before initiating a new therapeutic modality.

Current staging of lung cancer: an overview of current and newer approaches.

The purpose of this chapter is to update some of the current approaches to the pretreatment assessment of patients with lung cancer. We will place emphasis on both standard staging and newer techniques. Because of their clinical relevancy, small-cell (SCLC) and non-small-cell (NSCLC) lung cancers have been divided to emphasize the special needs and approaches to each.

Abdominal CT in the staging of small cell carcinoma of the lung.

Small cell carcinoma of the lung (SCCL) is a fulminant disease process with early extrathoracic dissemination. Surgery for cure has generally been abandoned and combined chemotherapy is the treatment of choice. The staging of SCCL is designed to identify areas of involvement for (1) comparison of therapeutic techniques, (2) prognostic determinations, (3) determination of sites of disease to use for assessment of response, and (4) for determination of areas that may require additional local therapy such as radiation or surgery. The staging evaluation, therefore, is designed to evaluate the extent of extrathoracic disease rather than just the presence of chest involvement. CT scanning has made a valuable contribution to the delineation of intrathoracic and metastatic disease and is now included in the staging workup of patients with SCCL since metastatic involvement of the liver, bone, bone marrow, CNS, and adrenal glands is common.

Traumatic avulsion of the ureter: computed tomography correlation.

Avulsion of the ureter is a rare but significant traumatic injury, and there is often a delay in diagnosis and treatment. Radiologic signs have been described for intravenous urography but are not always present. To our knowledge, the computed tomographic appearance of avulsion of the ureter has not been described. Herein, we report the contrast-enhanced computed tomography findings in a case of traumatic avulsion of the ureter.

Role of CT in excluding major arterial injury after blunt thoracic trauma.

The role of CT in the diagnosis of major vascular rupture following blunt decelerating chest trauma is controversial. Its value in excluding major arterial injury has not yet been determined. During a 12-month period we obtained dynamic enhanced thoracic CT studies in 20 patients with blunt decelerating thoracic trauma who had abnormal or equivocal mediastinal contours on chest radiographs. In all cases diagnosis was confirmed by either digital subtraction (18 patients) or conventional thoracic angiography (two patients). CT scans showed evidence of direct aortic injury in three patients and evidence of mediastinal hematoma in five others. Four of these eight patients had major arterial injury verified angiographically and at surgery. In two patients the CT scan was considered equivocal; both patients had normal thoracic angiograms. CT excluded direct vascular injury or mediastinal hematoma in 10 patients. All 10 had normal thoracic angiograms. This preliminary study suggests that, in patients sustaining blunt decelerating thoracic trauma, thoracic CT may be more valuable than chest radiography in excluding major vascular injury and, in some cases, may reduce the need for thoracic angiography.

Abdominal CT in the staging of small-cell carcinoma of the lung: incidence of metastases and effect on prognosis.

CT studies of the abdomen performed on 72 patients with small-cell carcinoma of the lung were retrospectively reviewed to assess the role of abdominal CT in staging. Forty-four of the 72 patients had extensive disease, defined as disease extending beyond the confines of one hemithorax, plus or minus mediastinal or ipsilateral supraclavicular disease or ipsilateral pleural effusion. Initial-staging abdominal CT revealed one or more sites of metastatic disease in 26 (59%) of these 44 patients, while 18 patients had normal initial CT examinations. Statistical analysis of patients with extensive disease revealed a significant increase in complete therapeutic response (p = .0054) and in the length of survival (p = .001) among those who had extensive disease without abdominal metastases as compared with those who had abdominal metastases on their initial abdominal CT examination. The development of new or recurrent abdominal metastases in general or in specific organs on follow-up scans obtained in 35 patients did not significantly decrease their survival time as compared with that of patients without such metastases. Our findings suggest that CT of the abdomen is beneficial in the initial staging of patients with small-cell carcinoma of the lung and provides prognostic information concerning response to therapy and length of survival.

Computed tomography of Kock and modified Kock continent ileal reservoir.

Kock or modified (Javadpour) ureteroiliostomy was performed in 5 patients following cystectomy for bladder carcinoma or exstrophy. Computed tomography was utilized to demonstrate alterations in pelvic anatomy after construction of the ileal reservoirs. Detailed evaluation of the inlet and outlet antireflux arms of the continent reservoir was possible. Appreciation of the expected alterations in pelvic anatomy accompanying the Kock or modified Kock procedure will be necessary to detect postoperative complications and to achieve early recognition of recurrent carcinoma. Potential advantages of the modified Kock ileal reservoir, as developed by Javadpour, are presented.

CT diagnosis of acalculous cholecystitis.

Acalculous cholecystitis is an uncommon but potentially fatal complication of prolonged critical illness. Both clinical and biochemical parameters lack sufficient sensitivity and specificity to confidently make the diagnosis preoperatively. Over a 2 year period we have evaluated 16 patients with suspected acute acalculous cholecystitis by CT. Based on CT findings, a positive diagnosis of acalculous cholecystitis was made in seven of these patients and confirmed pathologically in six. Criteria used in reaching the CT diagnosis and potential advantages of CT over other imaging modalities in this clinical context are considered.