Benefits of routine use of coronal and sagittal reformations in multi-slice CT examination of the abdomen and pelvis

AIM

To evaluate the usefulness of coronal and sagittal reformations from isotropic abdomino-pelvic computed tomography (CT) examinations.

METHODS

Fifty consecutive abdomino-pelvic CT examinations were reconstructed into two sets of axial source images: 0.9 mm section width with 0.45 mm reconstruction interval (isotropic) and 4 mm section width with 3 mm reconstruction interval. The isotropic dataset was reformatted into coronal and sagittal stacks with 4 mm section widths. Three readers independently reviewed the three image sets with 4 mm section widths. The coronal and sagittal reformations were compared with the axial images, in the same sitting, for depiction of lesions in various abdominal organs.

RESULTS

There was better visualization of lesions in the liver, kidneys, mesentery, lumbar spine, major abdominal vessels, urinary bladder, diaphragm and hips on the coronal reformations compared with source axial images (p<0.05). Sagittal reformations scored better than axial source images for showing lesions in the liver, thoracic spine, abdominal vessels, uterus, urinary bladder, diaphragm and hips (p<0.05). The coronal and sagittal series showed significant additional information in 23 and 17% of patients, respectively.

CONCLUSION

Radiologists should consider the routine review of at least one additional plane to the axial series in the interpretation of abdomino-pelvic CT studies.

Routine isotropic computed tomography scanning of the abdomen and pelvis

For 30 years, abdominal CT has been imaged and reviewed in the axial plane. It is now possible to carry out isotropic imaging of the whole abdomen and pelvis using a 40-channel scanner. This allows creation of coronal and sagittal reformats with the same image quality as the axial images. In this study, we present our experience of reviewing routinely coronal and, occasionally, sagittal reformats. We discuss situations where these nonaxial reformats are most beneficial.

Hepatic peliosis (bacillary angiomatosis) in AIDS: CT findings

Patients with acquired immunodeficiency syndrome are at risk of developing opportunistic infections and aggressive tumors. Computed tomographic examination is the usual method of evaluating the abdomen and pelvis in these patients. Although this technique is reasonably sensitive in detecting pathology, findings are often nonspecific. A case of hepatic peliosis (bacillary angiomatosis) in a patient with acquired immunodeficiency syndrome is presented.

Activity-based cost analysis: a method of analyzing the financial and operating performance of academic radiology departments

PURPOSE

To develop a methodology for an activity-based cost (ABC) analysis in an academic radiology department, to test the hypothesis that the business of academic radiology can be separated into three distinct businesses-clinical activity, teaching, and research-and to determine the effect of the current teaching paradigm on clinical productivity.

MATERIALS AND METHODS

Forty-seven key departmental activities were defined and distributed among the teaching, research, and clinical businesses. Individual radiologists determined the time spent in each of these activities by completing a detailed log of every activity performed during 2 weeks. All departmental revenue and costs were assigned to each activity in each of the three businesses.

RESULTS

The methodology provided a successful understanding of the relative costs of each of the businesses of teaching, research, and clinical activity. It also provided the departmental costs of performing the separate activities typical of each business. Key findings included the following: Faculty spends 72% of time in clinical activities, research is the most expensive service per direct activity hour, and clinical reads (23%) are the single largest departmental cost element.

CONCLUSION

ABC analysis can separate academic radiology into three businesses-teaching, research, and clinical-and provide a detailed understanding of the cost structure of each. This analysis identifies opportunities for improved quality of service, productivity, and cost within each business.

Fixed-facility workplace screening mammography

OBJECTIVE

Potential barriers to compliance with screening mammography guidelines include the cost and inconvenience involved with undergoing the procedure. Workplace screening with mobile mammography is one possible approach to the convenience barrier. However, fixed-facility workplace screening is a viable alternative for any company with a large workforce in one location. This paper describes our initial experience with one such fixed facility.

MATERIALS AND METHODS

The facility was a cooperative venture by a large pharmaceutical company and an academic radiology department to provide convenient, no-cost (to the patient) screening mammography to employees, dependents, and retirees more than 40 years old. The pharmaceutical company built the facility within its corporate headquarters and the academic radiology department provided the equipment and personnel. The company was billed a fixed cost per examination.

RESULTS

In the first 22 months of operation, 4210 (of 4559 scheduled) screening mammograms were obtained. The mean age of the population was 53 years old. Ninety percent of the screening mammograms were interpreted as negative or benign; 10% required additional workup. Of the screened population, 62 biopsies were recommended and 60 were performed. Of these, 42 were benign and 18 malignant. The cancer detection rate was 4.3 per 1000 (0.43%). At the time of diagnosis, six patients were stage 0, 10 patients were stage I, one patient was stage II, and one patient was stage III. Eleven of the 18 patients had minimal cancers. Of the patients who completed a satisfaction survey, 97% percent expressed a high degree of satisfaction with the screening process and stated they would use the facility in the future.

CONCLUSION

A fixed facility for workplace screening mammography is a viable way to provide nearly barrier-free access to high-quality mammography. Patient acceptance is high.

Sonography of the breast

Quality mammography remains the primary modality used to image the breast. Sonography currently is the most useful adjunctive technique to mammography, having roles in differentiating cystic from solid masses and in guiding interventional procedures. This article reviews these and other indications for breast ultrasound studies, including evaluation of palpable masses not visible in radiographically dense breasts, masses not completely evaluable with mammography, young patients especially susceptible to radiation damage, and abscesses. Ultrasound interpretation of cysts and solid masses are discussed, as are the relative disadvantages of ultrasound as a breast cancer screening tool.

Spiral CT angiography of the aorta

Imaging of the aorta and its branches has benefitted greatly from the development of spiral CT techniques, which are relatively fast and noninvasive. The volumetric acquisition of spatial information has permitted the computer to reformat images for inspection of the vessels by several methods from an infinite number of viewing angles. Most aortic diseases-including congenital anomalies, dissection, aneurysm, trauma, inflammation, infection, and thromboembolic disease-can be depicted with this technology. In selected cases, spiral CT may be the only imaging modality needed for the surgical planning of aortic repair. This report discusses the CT angiography technique, its application to a variety of disease states, its role relative to other imaging modalities, and guidelines for patient selection.

Magnetic resonance imaging for detection of prostate cancer metastatic to bone

The diagnosis of prostate cancer metastatic to bone currently is made with plain x-rays, radionuclide bone scans, and acid and alkaline phosphatases. We used magnetic resonance imaging (MRI) in 18 patients with known prostate cancer to resolve conflicting evidence of metastases found on bone scans, plain films and serum enzyme determinations. Of 8 bone scans interpreted as positive MRI was read as negative for metastatic disease in 2. Of 5 negative bone scans 1 MRI study was interpreted as positive. All 5 equivocal bone scans demonstrated no osseous lesions on MRI. In addition, in 6 patients with evidence of bone metastases the serial MRI scans following hormonal therapy demonstrated radiographic and clinical improvement. We conclude that MRI is helpful in the diagnosis of metastatic prostate cancer when other radiographic examinations are enigmatic and that MRI can be used to determine the response to hormonal treatment.

Gadolinium-enhanced MRI of soft tissue masses

The efficacy of gadopentetate dimeglumine (Gd-DTPA) enhanced magnetic resonance (MR) imaging in the diagnosis and differentiation of soft-tissue, neoplastic and non-neoplastic lesion has not been well established. Thirty patients with soft tissue masses (18 neoplastic and 12 non-neoplastic) were studied, using MR imaging with and without administration of Gd-DTPA. Gd-DTPA proved helpful in characterisation of several entities, including differentiation of solid mass from proteinaceous cyst, demonstration of tumour nodules within haemorrhagic or necrotic masses, and delineation of tumour adjacent to oedema. The use of Gd-DTPA may provide additional information for tissue specificity and, in complicated cases, Gd-DTPA may also provide essential information that cannot be obtained using other methods. We recommend the use of contrast enhanced MR as an adjunct to conventional MR imaging in the initial assessment of musculoskeletal soft tissue masses. However, T2-weighted images show better tissue contrast of the lesions, and are equal to contrast enhanced images in delineation of tumour margins. Non-contrast enhanced images are, therefore, probably adequate for the delineation of lesions for surgical planning when a diagnosis has already been made.

Leukocyte scintigraphy in the diagnosis of mycotic aneurysm

Early diagnosis of a mycotic aneurysm is critical, but often unsuspected, due to the insidious onset of symptoms related to occult infection. This study was undertaken to assess the role of leukocyte scintigraphy in establishing the diagnosis of mycotic aneurysm. The records of all patients with possible mycotic aneurysm between 1985 and 1991 were reviewed. Seven patients had leukocyte scintigraphy and computed tomography (CT), three also had magnetic resonance imaging (MRI) and three had angiography as part of the diagnostic workup. CT and MRI detected aneurysms in five of the seven patients, but CT scans were misinterpreted in two patients as indicative of abscess only. In six patients, infection could not be differentiated from thrombosis, seroma or hemorrhage by CT or MRI. Leukocyte scintigraphy was positive in all four patients with infected aneurysms; it was negative in two of the three noninfected aneurysms and equivocal in the third. Leukocyte scintigraphy provided a useful early survey that demonstrated evidence of infected aneurysms in four patients and identified other sites of infection in two patients. Leukocyte uptake complemented CT, MRI and angiographic findings distinguishing between seroma/hematoma and adjacent infection to establish a preoperative diagnosis of infected aneurysms.

Computed tomographic findings of small-bowel volvulus

Computed tomographic examinations of two cases of small-bowel volvulus were reviewed. At laparotomy, both cases were proved to be secondary to adhesions. CT examinations showed focal, wedge-shaped, edematous mesentery with trapped fluid between mesenteric folds radiating toward the site of torsion. One case showed the superior mesenteric vein spiraling around the superior mesenteric artery. At laparotomy, affected small-bowel loops showed ischemia in both cases. CT performed in patients with acute abdomen may show findings suggestive of small-bowel volvulus.

CT diagnosis of small-bowel obstruction: efficacy in 60 patients

We retrospectively compared the CT findings in patients with and without surgically proved small-bowel obstruction to evaluate the role of CT in diagnosing the presence and cause of obstruction. In the patients with obstruction, we compared the CT findings with findings on plain abdominal radiographs and contrast studies of the small intestine. CT criteria used for the diagnosis of obstruction were dilated small-bowel loops proximal to the suspected site of obstruction and collapsed or normal-appearing loops of small bowel distal to the obstruction. Receiver-operating-characteristic analysis suggested the optimum balance of sensitivity and specificity was achieved when 2.5 cm was used to indicate dilatation of the small bowel. On the basis of these criteria, the presence of obstruction was correctly diagnosed in 27 (90%) of 30 patients with proved obstruction, and obstruction was not diagnosed in the patients without obstruction. The cause of the obstruction was evident on CT in 14 of the 30 obstructed patients: abscess (five), neoplastic lesion (three), peritoneal carcinomatosis (three), and other (three). Adhesions were responsible for the obstruction in 13 of 15 patients in whom the cause was not shown on CT. In six patients in whom findings on plain abdominal radiographs were normal, the CT scan was positive for obstruction. However, in the three patients whose CT scans were falsely negative for obstruction, findings suggesting obstruction were seen on plain films. Of 15 patients who had both CT and contrast studies of the small intestine, CT offered more information concerning the cause of obstruction in six (40%), primarily by demonstrating significant extraluminal abnormalities. CT and gastrointestinal contrast studies gave concordant results in eight patients with obstruction. In only one patient did the gastrointestinal contrast study give more diagnostic information. We conclude that CT scanning demonstrates accurately the presence of high-grade small-bowel obstruction and may be the technique of choice when extraluminal abnormalities are suspected or when prompt, efficient, and comprehensive evaluation is required.

Imaging of the biliary sump syndrome

Side-to-side choledochoduodenostomy is a safe and effective surgical technique to improve biliary drainage in selected patients. The segment of common bile duct between the anastomosis and the ampulla of Vater may act as a stagnant reservoir or sump. When debris, stones, or infected bile accumulates in the sump, usually because of malfunction of the ampulla of Vater, recurrent abdominal pain or symptoms of cholangitis, pancreatitis, or biliary obstruction may develop. This uncommon (0.14-1.30%) complication is known as the sump syndrome. On imaging studies, diagnostic findings are debris or stone(s) in the common bile duct. Suggestive findings are dilated bile or pancreatic ducts, and changes due to pancreatitis, cholangitis, or liver abscess. Patients with this syndrome frequently have multiple imaging studies before the condition is recognized. The purpose of this essay is to illustrate the imaging findings of this syndrome.

Postoperative bone marrow alterations: potential pitfalls in the diagnosis of osteomyelitis with In-111-labeled leukocyte scintigraphy

Scintigraphy was used after injection of technetium-99m methylene diphosphonate (MDP) and indium-111-labeled white blood cells (WBCs) to assess for the presence of osteomyelitis in 97 patients who had undergone prior surgical procedures. Thirty-four patients with abnormal In-111-labeled WBC patterns underwent restudy with Tc-99m albumin colloid (AC). Scintigraphic findings were considered positive for osteomyelitis whenever localization of In-111-labeled WBCs exceeded Tc-99m AC activity in extent or focal intensity (discordant pattern). Ten of 12 patients with culture-proved osteomyelitis had discordant patterns; two had false-negative (concordant) patterns. The cases of 20 of 22 patients without infection who were considered to have osteomyelitis on the basis of patterns of In-111-labeled WBCs and Tc-99m MDP were reclassified correctly on the basis of concordant patterns of In-111-labeled WBCs and Tc-99m AC. Radiocolloid images improved the overall scintigraphic specificity for osteomyelitis from 59% without bone marrow imaging to 92%; sensitivity decreased from 94% to 88%.

MR imaging of Hippel-Lindau disease: value of gadopentetate dimeglumine

Hippel-Lindau disease is an autosomal dominant disorder characterized by tumors of the central nervous system and abdominal viscera. Frequent multisystem radiologic evaluation of persons at risk is desirable. Twenty-seven patients with Hippel-Lindau disease or a family history of the disease were examined with both unenhanced and gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging to study the usefulness of the contrast medium in the evaluation of these patients. The MR studies were correlated with computed tomographic (CT) scans in seven patients and cerebral angiograms in five. Twelve patients had hemangioblastomas in the brain, and eight of these patients also had spinal cord lesions (most were multiple), well demonstrated with gadopentetate dimeglumine. Contrast-enhanced MR imaging enabled detection of more central nervous system lesions and provided better delineation than unenhanced MR imaging, CT, or angiography. In addition, four patients with multiple renal cysts seen on CT scans and unenhanced MR images had enhancing lesions that were later proved to be renal cell carcinoma at angiography and/or surgery. Four patients had cystic lesions in the pancreas that did not enhance and were later proved to be pancreatic cysts. The authors conclude that gadopentetate dimeglumine-enhanced MR imaging appears to be a useful method for evaluating and following up patients with Hippel-Lindau disease.

Insular carcinoma: a distinct thyroid carcinoma with associated iodine-131 localization

Insular carcinoma, once considered a poorly-differentiated thyroid cancer, has been reclassified as a distinct thyroid neoplasm. Since this neoplasm is composed of follicular epithelial cells, it may concentrate radioiodide (131I) making postoperative 131I imaging for detection of metastases and radiotherapy possible. A 20-yr review of 35 cases diagnosed as anaplastic or undifferentiated thyroid carcinoma at this medical center revealed five patients with insular carcinoma. Four patients showed postoperative 131I localization and received therapeutic doses of 131I. Three of the four showed extrathyroidal 131I localization in neoplastic lesions. In one patient, the resolution of metastatic lesions by magnetic resonance and 131I imaging suggests that 131I may have an important therapeutic role in this aggressive neoplasm.

CT of abdominal abscess with fistulous communication to the gastrointestinal tract

We review CT of 24 cases of intraabdominal abscess with fistulous communication to the GI tract confirmed by GI contrast study or fistulogram. Underlying causes of fistulization included recent GI tract surgery (13), diverticulitis (four), unknown etiology (three), malignant neoplasm (two), trauma (one), and pancreatitis (one). Thirteen (54%) abscesses showed air-fluid levels, 14 (58%) showed air bubbles, and seven (29%) showed both. Bowel contrast material was administered in 21 cases, and optimal bowel opacification was effected in 16. However, contrast extravasation into the abscess was noted in only six cases. We conclude that an air-fluid level may indicate the presence of a fistulous communication to the GI tract, but its absence does not necessarily mean there is no communication. Also, recognition of contrast within the abscess is uncommon even with optimal bowel opacification. In cases of clinical suspicion of internal fistula, a fistulogram or GI contrast study should be performed.

Gadolinium-enhanced MR imaging in the management of a midline cerebral dysgerminoma

Magnetic Resonance (MR) imaging has proved to be an excellent modality for the evaluation of CNS tumors and detection of metastatic seeding through CNS pathways. We present a case of cerebral dysgerminoma in which the use of gadopentetate dimeglumine (Gd-DTPA) enhancement added important information in lesion detection and delineation for treatment planning. Our results, and a review of recent literature, suggest that Gd-DTPA-enhanced MR imaging may be useful for initial and follow-up evaluation of CNS dysgerminomas.

Vertebral compression fractures: distinction between benign and malignant causes with MR imaging

Magnetic resonance (MR) imaging was performed on 64 patients with 109 vertebral compression fractures, the cause of which could not be determined from plain radiographs. Twenty-five fractures were due to malignancy; 84 were caused by a benign process. In 22 of the 25 fractures caused by malignancy, MR images showed complete replacement of normal bone marrow, whereas 47 of the 61 benign fractures without history of trauma had complete preservation of normal bone marrow. The remaining 14 benign fractures had incompletely preserved bone marrow in a regular pattern. In two of the three remaining malignant fractures, the bone marrow replacement also was incomplete but with an irregular pattern. In cases of recent trauma or primary bone marrow abnormalities, the configuration and signal of remaining bone marrow were not useful in differentiating among malignancy, osteoporosis, and other benign processes. When criteria based on complete loss or preservation of marrow and marrow configuration in cases of incomplete loss were used, the accuracy in differentiating benign from malignant fractures was 94%. MR imaging may be a useful adjunct in differentiating benign from metastatic fractures and may provide information not available with other imaging methods.

Osteomyelitis of the foot in diabetic patients: evaluation with plain film, 99mTc-MDP bone scintigraphy, and MR imaging

Diagnosis of osteomyelitis of the foot in diabetic patients may be difficult because of the coexistence of chronic cellulitis, vascular insufficiency, and peripheral neuropathy. This study compared the diagnostic accuracies of plain films, bone scans, and MR imaging studies in diabetic patients with suspicion of osteomyelitis of the foot. Twenty-nine plain radiographs, 20 bone scans, and 30 MR studies were obtained in 24 patients. Twenty-nine bones from 14 patients were pathologically proved either positive (25 bones) or negative (four bones) for osteomyelitis. Another 15 bones (10 patients) studied with MR had no pathologic proof, but the bones healed with only local wound care and/or a short course of oral antibiotics. These patients had trauma, cellulitis, or unhealed ulcers. The sensitivity and specificity of plain films were both 75%. Bone scans had a very low specificity (100% false-positive rate). A negative bone scan should strongly exclude the probability of osteomyelitis. Unlike the findings in previous reports, MR had much higher sensitivity and specificity than bone scans in detecting osteomyelitis in diabetic patients. When the 10 patients without pathologic proof (those who presumably had neuroarthropathy, vascular insufficiency, and/or cellulitis) were included, the sensitivity and specificity of all three techniques decreased. Our experience with this small group of patients suggests that MR is a useful imaging technique for diagnosing osteomyelitis of the foot in diabetic patients.

Utilization of screening mammography: comparison of different physician specialties

Data obtained on 426 consecutive patients referred to a breast center by 122 physicians, including family practitioners, general surgeons, and other specialists, showed that the obstetricians-gynecologists referred the greatest average number of patients per physician, with more than 50% of these referrals for screening mammography. Internists referred fewer patients by nearly a factor of ten, with only one-third of these patients referred for screening mammography. Internists may be the weakest link in the utilization of screening mammography.