Impact of abdominal CT on the management of patients presenting to the emergency department with acute abdominal pain.

OBJECTIVE: The purpose of this study is to document the impact of CT performed in the emergency department of patients presenting with nontraumatic acute abdominal pain. SUBJECTS AND METHODS: Fifty-seven patients were enrolled in this prospective study. Using a computer order entry system, emergency department physicians were required to report their most likely diagnosis, level of certainty, and management plan for their patients before ordering abdominal CT. After CT was performed, each physician was required to provide again his or her diagnosis, level of diagnostic certainty, and treatment plan. The outcome of each patient was evaluated by either surgery, other imaging studies, or clinical follow-up. RESULTS: After the abdominal CT, physicians' mean level of certainty in their diagnoses increased by 1.5 points (on a five-point scale; p < 0.0001). Patient management was changed in 33 (60.0%) of 55 patients. Planned treatment before CT was admission in 42 patients. Actual admissions after CT totaled 32 patients (excluding the two patients in whom preimaging information was not recorded). Thus, the net effect of abdominal CT scanning was to avert 10 (23.8%) of 42 hospital admissions. CONCLUSION: CT performed in the emergency department increases the physician's level of certainty, reduces hospital admission rates by 23.8%, and leads to more timely surgical intervention.

Renal failure resulting from infiltration by inflammatory myofibroblastic tumor responsive to corticosteroid therapy.

Inflammatory myofibroblastic tumor (IMT) is a rare disease of inflammatory and spindle cell proliferative lesions in multiple sites. Most frequently reported in the lungs, a variety of extrapulmonary sites have been described. We report the first case of IMT causing renal failure by massive bilateral renal infiltration. Renal function continued to deteriorate (peak serum creatinine level, 8.4 mg/dL) despite placement of a ureteral stent. The kidneys were diffusely enlarged on computed tomographic (CT) scan. Renal biopsy showed myofibroblastic proliferation and inflammatory infiltration. Renal failure responded favorably over weeks to corticosteroid therapy (serum creatinine level, 2.8 mg/dL) with a marked reduction in bilateral renal enlargement by CT scan.

Pitfalls and sources of error in staging rectal cancer with endorectal us.

Endorectal ultrasound (US) is an accurate technique for local staging of rectal cancer. Because the choice of surgery depends on the level of tumor invasion and lymph node involvement, the surgeon relies largely on endorectal US findings when planning treatment. However, staging inaccuracies can occur due to over or underestimation of tumor depth, misinterpretation of lymph node involvement, and operator inexperience. Technical pitfalls in US of the rectal wall include proximity of the lesion to the anal verge, improper balloon inflation, a nonperpendicular imaging plane, shadowing artifacts due to air or stool, reverberation artifacts, refraction artifacts, and a transducer gain setting that is too high. Sources of error in tumor staging with endorectal US include interpretation differences, endosonologist bias, tumor location, tumor stenosis, peritumoral inflammation, postbiopsy and postsurgical changes, post irradiation changes, hemorrhage, and pedunculated or villous tumors. Node size and appearance are not reliable indicators of lymph node involvement. Awareness of these sources of error will improve the technical quality of endorectal US studies and allow more accurate tumor staging.

MR venography of left renal vein anomalies.

The examinations of 71 patients having comprehensive 2D time of flight (TOF) abdominal magnetic resonance venography (MRV) in three planes (axial, sagittal and 10 degrees offset coronal) were evaluated to assess the appearances of anomalous left renal veins as shown by MRV. Six cases of circumaortic left renal vein (CLRV) (8.5%) and one example of retro-aortic left renal vein only (1.4%) were identified, an incidence higher than that in previous computed tomography (CT) studies but comparable to venographic and post-mortem investigations. All retro-aortic components passed in a caudal direction to join the inferior vena cava (IVC) inferior to the anterior limb. MRV acquired in the sagittal plane was found to be most useful for identifying these variants and provided highest signal by avoidance of in-plane flow saturation effects.

Time-of-flight MR angiography of the portal venous system: value compared with other imaging procedures.

OBJECTIVE: The purpose of this study was to retrospectively compare two-dimensional time-of-flight MR angiography with other imaging procedures in the evaluation of the portal venous system in 152 consecutive patients. MATERIALS AND METHODS: The findings on MR angiography performed on 152 patients to depict breath-hold, two-dimensional time of flight MR angiography. Selective arterial presaturation, bolus tracking, and three-dimensional reconstruction were used routinely. Findings were correlated with findings on sonography (104 patients), CT (8 patients), and conventional digital subtraction angiography (19 patients) as well as surgery (23 patients). RESULTS: Agreement between results of MR angiography and alternative types of imaging was excellent (99%). Agreement with sonography (100 of 104), CT (8 of 8), conventional angiography (18 of 19), and surgery (23 of 23) was good. Visualization of varices and spontaneous shunts by MR angiography was superior to that by other imaging techniques. CONCLUSION: Our experience shows that time-of-flight MR angiography is reliable and accurate for depicting portal venous anatomy. MR angiography shows vessels that are not visible with sonography. Complicated pathology is clearly visualized in a way that is not possible with other techniques.

Body magnetic resonance angiography and its effect on the use of alternative imaging--experience in 1026 patients.

Time-of-flight magnetic resonance (MR) angiography has been described for numerous applications but the number of patients described in published reports is usually relatively small. There is little information concerning the general utility of MR angiography in the body, outside the cranial circulation, or its effect on use of other imaging studies. Utilization of two-dimensional (2D) time-of-flight MR angiography over a 3 year period was reviewed to determine its accuracy and impact on other imaging modalities. Cranial and cardiac studies were excluded. Correlation was made with alternative imaging and surgical findings. Between January 1990 and December 1992 2D time-of-flight MR angiography was used to examine 1026 patients. MR angiography was used most frequently to examine the venous system. There was a slight reduction in the use of alternative imaging with two exceptions. When chest MR venography was performed, alternative imaging was completely abolished. Also, contrast portal venography was virtually eliminated. Five errors (0.2% of total MR angiography examinations) were recorded. Time-of-flight MR angiography, especially MR venography, is accurate and can replace contrast venography for abdominal and thoracic applications. Cost and limited availability means that other imaging, usually ultrasound, often precedes MR angiography.

The prevalence and clinical significance of lymphadenopathy in primary biliary cirrhosis.

We present the results of a retrospective review of abdominal computed tomography, ultrasound, and magnetic resonance examinations of 12 patients with primary biliary cirrhosis undertaken to determine the prevalence and clinical significance of previously reported coexistent intra-abdominal lymphadenopathy in patients with this disorder. Lymphadenopathy, in the form of bulky periportal and retroperitoneal nodes, was identified in a single patient secondary to an occult metastatic adenocarcinoma. We conclude that coexistent intra-abdominal lymphadenopathy occurring in patients with primary biliary cirrhosis is uncommon. Although it may represent a benign component of the primary disease, it may equally be due to unsuspected coexistent occult malignancy.

Magnetic resonance angiography of the central chest veins. A new gold standard?

PURPOSE: The systemic chest veins may be difficult to show comprehensively by contrast venography, especially if there is limited venous access or contraindications to intravenous contrast. As an alternative, can magnetic resonance angiography (MRA) reliably detect occluded chest veins and predict suitable sites for central venous access? PATIENTS AND METHODS: Eighty-four patients were examined using breath-hold time-of-flight MRA and three-dimensional image reconstruction. Thirty-three were evaluated to identify possible central venous access. Fifty-seven patients were examined to diagnose and stage central venous occlusion. RESULTS: The associated diagnoses were malignancy 46, parenteral nutrition 21, hemodialysis 6, chemotherapy 4, and other long-term venous access 7. Of the 28 patients in whom MRA predicted a patent site for central venous access, satisfactory access was achieved. In two patients, cannulation of veins shown to be occluded on MRA was attempted unsuccessfully. Correlation with contrast venography was available in 17. There was agreement with MRA concerning the level of occluded veins in all cases. Contrast venography did not show all patent veins, including some accessed during surgical line placement. CONCLUSION: Compared with surgical line placement or contrast venography, MRA of the systemic chest veins is accurate. Patent and occluded chest veins are reliably defined, including potential sites for central line placement, in a way that is not possible with other techniques. MRA may be the new "gold standard" for defining systemic venous anatomy in the chest.

Imaging infections in diabetic patients.

Infectious processes in diabetic patients may manifest in an unusual clinical manner, and a thorough understanding of available imaging modalities is helpful in making the diagnosis. Similarly, interpretation of imaging studies should be performed in conjunction with a thorough knowledge of the patient's clinical condition and the presence of neuropathic or vascular complications because these may affect image interpretation and choice of imaging modality.

Clival marrow changes in AIDS: findings at MR imaging.

PURPOSE: To determine the prevalence and clinical significance of marrow changes in the clivus identified at magnetic resonance (MR) imaging in patients with the acquired immunodeficiency syndrome (AIDS). MATERIALS AND METHODS: MR images of the head of 119 patients with AIDS and 119 control subjects were retrospectively reviewed. Marrow signal intensity patterns in the clivus of each patient were evaluated and scored as type 1 (homogeneous high signal intensity on T1-weighted images [normal]), type 2 (heterogeneous low signal intensity on T1-weighted images [abnormal]), or type 3 (homogeneous low signal intensity on T1-weighted images [abnormal]) and correlated with clinical parameters including CD4 counts, evidence of previous systemic disease, and presence of coexistent disease on corresponding MR head images. RESULTS: Abnormal clival signal intensity (type 2 and 3) was observed in 64 (54%) patients with AIDS and nine (7.5%) control subjects (P < .001), correlating with both a marked decrease in CD4 count (P < .001) and the presence of systemic disease (P < .001). CONCLUSION: Clival marrow signal abnormality is commonly identified in patients with AIDS and may be a marker of advanced disease.

Magnetic resonance angiography in transjugular intrahepatic portosystemic stenting: comparison with contrast hepatic and portal venography.

In order to highlight the role of magnetic resonance angiography [MRA] in the assessment of patients pre-transjugular intrahepatic portosystemic shunt (TIPS) stenting, the MRA images of portal and hepatic veins of 21 patients were compared with the images from contrast portal and hepatic venograms performed on the same patients at the time of TIPS stenting (20 patients). MRA enabled accurate, non-invasive, multiplanar imaging of portal and systemic venous anatomy in each of the patients studied. MRA facilitated accurate determination of vessel patency and flow direction, images correlating exactly with contrast venograms of hepatic and portal veins in each case. In one patient, identification of occult hepatocellular carcinoma extending to the portal vein lead to the postponement of the TIPS procedure.

MR imaging of the thoracic aorta: comparison of spin-echo, angiographic, and breath-hold techniques.

PURPOSE: To compare magnetic resonance (MR) angiography and fast MR imaging with spin-echo (SE) and non-MR imaging techniques in examination of the thoracic aorta. MATERIALS AND METHODS: Eighty-nine patients underwent breath-hold or cine MR angiography; SE was used in 67 patients and fast MR imaging in 28. A comparison was made with non-MR imaging (transthoracic echocardiography in 49 patients, transesophageal echocardiography in 18, and arteriography in 33) findings and those from surgery or autopsy (16 patients). RESULTS: MR angiography enabled differentiation of slow flow from thrombus, demonstrated aortic valve anatomy and aortic regurgitation, and accurately showed anatomy with only one error. It demonstrated two communications, flaps, and three branch stenoses better than SE, which produced some artifacts that mimicked thrombus or flaps. Fast MR imaging often produced artifacts or poor image quality (10 of 28 patients). CONCLUSION: Compared with SE MR imaging, MR angiography provides additional useful anatomic and functional information concerning diseases of the thoracic aorta, usually gained only with echocardiography or arteriography.

Imaging of the portal venous system in patients with cirrhosis: MR angiography vs duplex Doppler sonography.

OBJECTIVE: To determine the relative performances of MR angiography and duplex Doppler sonography in the evaluation of the portal venous system in patients with portal hypertension, we compared two-dimensional time-of-flight MR angiography and duplex Doppler sonography in 60 sequential patients with cirrhosis. All 60 subsequently underwent liver transplantation. SUBJECTS AND METHODS: MR imaging and duplex Doppler sonography were performed on the same day, and in all patients the imaging findings were validated at surgical exploration. Five transplantation candidates had surgical portosystemic shunts in situ at the time of imaging. MR images were acquired during breath-holding, and flow in the portal vein was evaluated with presaturation bolus-tracking MR imaging. Sonography included color Doppler and pulsed gated Doppler images of the portal vein. MR angiograms and sonograms were analyzed independently and prospectively for patency of the portal vein, patency of surgical shunts, and grade and distribution of portosystemic collateral vessels. Scores on both imaging techniques were compared by using regression analysis. RESULTS: MR angiograms showed all five cases of portal vein occlusion and all 55 cases of patent portal veins. Sonograms showed three of five cases of portal vein occlusion and 52 of 55 cases of patent portal veins. The techniques concurred in assessing flow direction in 54 (90%) of 60 patients, and both procedures enabled detection of occlusive portal vein thrombus in one patient. We found a significant correlation (p < .001) between the grades of gastric varices detected with MR angiography and surgery but no significant correlation between the grades seen on sonography and found at surgery. Shunt patency in four of five patients and shunt occlusion in one were correctly assessed on MR angiograms, whereas three of these shunts were not visible on sonograms. CONCLUSION: Our results show that MR angiography is more reliable than duplex Doppler sonography for evaluating the portal venous system in patients with portal hypertension caused by cirrhosis.

Use of magnetic resonance angiography in the pretransplant evaluation of portal vein pathology.

The assessment of portal vein patency in patients selected as candidates for orthotopic liver transplantation should be accomplished noninvasively and with great accuracy. Magnetic resonance angiography (MRA) is a new technique that is completely noninvasive and is capable of graphically assessing portal vein anatomy and blood flow. In an attempt to establish the accuracy of portal venous MRA, 74 patients with established cirrhosis underwent abdominal MRA prior to liver transplantation. MRA findings were correlated with surgical findings at the time of transplantation in all patients, and were shown to be extremely accurate. The three-dimensional images generated by MRA and computer postprocessing allowed for correct identification of portal venous anatomy in all of the patients examined. We conclude that MRA is an extremely useful method of determining portal venous anatomy in potential liver transplant patients, and potentially offers greater definition and clarify compared with other non-invasive methods.

Central venous occlusion: MR angiography.

The authors evaluated time-of-flight magnetic resonance (MR) angiography in 30 patients with suspected thoracic venous occlusion. The results of the MR studies were compared with results at contrast venography in 22 patients and at central venous cannulation in seven of the remaining eight patients. Twenty-eight patients had abnormalities on MR venograms; 21 of these abnormalities involved multiple veins. Eight patients had superior vena cava (SVC) occlusion with retrograde azygos blood flow, and two patients had nonocclusive SVC thrombus. Fifteen patients had thrombosis involving the brachiocephalic veins; 14, involving the subclavian veins; and eight, involving the internal jugular veins. Correlation was excellent between findings of venous obstruction and occlusion at contrast venography and MR angiography. MR imaging provided more comprehensive information than catheter venography on central venous anatomy and blood flow. For evaluation of central veins, MR angiography is an accurate and graphic technique that may succeed in cases in which other methods may give inadequate findings or may be impossible to perform.

Noninvasive liver imaging: new techniques and practical strategies.

The goals and expectations of liver imaging have expanded as the treatment options for a range of liver diseases have advanced. Unfortunately, no single modality can yet achieve all the goals that an ideal imaging modality should satisfy. Currently available liver imaging techniques should be considered complementary rather than competitive in their roles, and appropriate utilization of the expanding technical capabilities of cross-sectional imaging depends on many considerations, including patient factors, referring physician expectations and biases, experience and bias of the radiologist, and the availability of state-of-the-art technical capabilities for each modality. This article reviews the advantages, limitations, and roles of fast CT and fast MR liver imaging techniques as well as the complimentary role of ultrasound, and the future of new imaging considerations including the role of contrast agents.

Abdominal magnetic resonance venography.

With the refinement of fast gradient-echo imaging, it is now possible to perform abdominal magnetic resonance venography completely noninvasively, without the use of oral or injected contrast agents. In this paper, we emphasize two-dimensional, time-of-flight angiographic techniques, as applied to the study of patency and flow in the veins of the abdomen. Magnetic resonance venography is routinely applicable to patients with portal disease, or suspected occlusion of the inferior vena cava, iliac veins or renal veins. Sequential, single-slice venographic images, acquired during breath holding, can be postprocessed to form projected venograms. Hemodyanmic information is derived using presaturation schemes, bolus-tracking or phase imaging. These techniques can also be used to establish the integrity of surgical portosystemic shunts.

Liver transplantation: MR angiography with surgical validation.

Thirty patients (mean age, 45 years) were evaluated with magnetic resonance (MR) angiography before liver transplantation to assess the accuracy of MR angiography. A series of breath-hold, two-dimensional images were acquired and subsequently processed to form three-dimensional projection angiograms. Graphic information on blood flow in the portal vein was acquired by using presaturation bolus tracking. Correlative duplex ultrasound (US) was performed in 28 patients, and surgical or autopsy correlation was available in all cases. MR angiography demonstrated patency of the portal vein in 26 (96%) of 27 patients, made possible the diagnosis of portal venous occlusion in three of three patients, depicted reversed portal flow in one patient, and provided clear delineation of the extent of varices and specific portosystemic collateral vessels. When duplex US was successful, there was full agreement with MR angiographic results in assessing portal vein patency and flow direction. All of the MR findings were corroborated at surgical exploration or autopsy. The authors conclude that MR angiography is very accurate in the portal system and is valuable in preoperative assessment for liver transplantation.

Dynamic MR imaging of the liver with Gd-DTPA: initial clinical results.

Gd-DTPA was evaluated as a hepatic contrast agent for MR imaging. Twenty-six consecutive patients referred for suspected masses in the liver were studied at 1.5 T. Fourteen patients had hepatic metastases and one patient each had cholangiocarcinoma and multicentric hepatocellular carcinoma. Four patients had cavernous hemangiomas and the remainder had other benign lesions. Diagnoses were proved by biopsy, sonography, or radionuclide scintigraphy in 23 cases and by autopsy in one case. Precontrast scans were obtained by using standard pulse sequences. In addition, breath-hold scans were obtained before and after bolus administration of 0.1 mmol/kg Gd-DTPA by using a multislice T1-weighted gradient-echo pulse sequence with an ultrashort echo time. Mean lesion-liver signal difference/noise increased by 50% (p less than .01) in the immediate postcontrast phase. In two of 26 cases, multiple additional lesions as small as 3 mm were detected after contrast administration that were not seen before contrast administration. In no case was lesion-liver contrast worsened on scans obtained immediately after administration of contrast material. However, on delayed scans, detection of lesions worsened in some cases because of equilibration of contrast material between liver and lesion. These initial clinical results suggest that enhancement with Gd-DTPA is a practical method for improving lesion-liver contrast and has the potential to improve the accuracy of MR imaging in the liver. However, optimized fast imaging techniques are required for best results.