Radiological follow-up of inverted papilloma

The aim of this study was to describe cross-sectional imaging features of recurrent papilloma of the nasal fossa and paranasal sinuses and to evaluate the role of MR and CT in the postoperative follow-up of this lesion. Magnetic resonance imaging and CT of ten patients who presented recurrence of inverted papilloma were reviewed and correlated to initial imaging, endoscopy, and surgical reports. Imaging patterns of recurrent inverted papilloma are identical to those of initial tumors and recurrence location is closely related to the site of the former lesion. Magnetic resonance is more efficient than CT for the diagnosis and evaluation of extensions. Magnetic resonance supplies the deficiencies of endoscopy in case of extensions to the frontal sinus or the lateral recess of the antrum, especially if mucosal hyperplasia or sinusitis is associated. Magnetic resonance imaging is the first imaging modality to perform in the follow-up after removal of inverted papilloma. Received: 28 April 1999; Revised: 18 November 1999; Accepted: 19 November 1999     

CT diagnosis of diaphragm injuries

Admission supine chest radiographs are the initial and most commonly performed imaging study to evaluate the thorax following trauma. Whenever the chest radiograph is ambiguous or suggestive of a diagnosis of acute diaphragmatic injury, CT is the next study of choice since it is generally available and often used to examine other body regions of the polytraumatized patient. CT is usually diagnostic, particularly if supplemented by multiplanar reformations obtained using a thin slice thickness. Currently MR imaging is used at our trauma center to evaluate the diaphragm in patients with an indeterminate diagnosis after spiral CT. A limited MR imaging examination with T1-weighted sagittal and coronal imaging has been extremely accurate in establishing or excluding diaphragm injury.     

Safety of colon contrast material in (helical) CT examination of patients with suspected diverticulitis

Purpose: Today patients with suspected diverticulitis are commonly imaged with a CT scan utilizing a variety of methods of contrast medium administration. Although CT with rectally administered colon contrast has demonstrated a high diagnostic accuracy, concerns have been raised over its safety in patients with diverticulitis. The following retrospective investigation was undertaken to answer this concern. Materials and methods: Between January, 1997, and July, 1999, 308 patients with suspected diverticulitis were examined in the Emergency Radiology Division of the Massachusetts General Hospital by means of a helical CT scan performed with rectally administered colon contrast material. The patients' CT findings were correlated with their clinical courses and/or surgical findings. Results: Of the 308 CT scans, 115 (37.3 %) were positive for diverticulitis. Of 193 patients without diverticulitis, 91 (47.1 % of patients without diverticulitis) had alternative diagnoses made by CT, such as small bowel obstruction, epiploic appendagitis, and urinary tract calculi. No complications due to colon contrast material were noted. Even in cases where there was free extraluminal air, no extravasated contrast material was seen. Rectally administered colon contrast was well tolerated by patients and provided excellent large bowel opacification. This method saved imaging time in an emergency setting, as there was no need to wait for oral contrast to reach the colon. Conclusion: Out of 308 CT scans, there were no complications from the use of rectally administered colon contrast material. No case of traumatic bowel perforation secondary to colon contrast material was observed. Rectally administered colon contrast material is safe in the CT examination of patients with suspected diverticulitis.     

MR imaging of lumbar facet joint synovial cysts

The increasing application of magnetic resonance (MR) imaging of the spine has raised the awareness of lumbar facet synovial cysts (LFSC). This well recognised, yet uncommon condition, presents with low back pain and radiculopathy due to the presence of an extradural mass. The commonest affected level is L4/5 with a mild degenerative spondylolisthesis a frequent associated finding. MR imaging is the technique of choice to detect and diagnose a LFSC. This pictorial essay, drawing on experience of 43 cases seen in 40 patients, illustrates the spectrum of appearances that can be encountered and suggest differing causes for the variable signal characteristics exhibited. Computed tomography (CT) can be of value in some cases to aid interpretation of the MR images. In addition, CT facet arthrography by injection of air or iodinated non-ionic contrast medium may be used to confirm the diagnosis in doubtful cases as well as noting whether the patients presenting symptoms can be provoked. A comprehensive review of the existing literature is presented. Received: 22 September 1998; Revised: 29 June 1999; Accepted: 30 June 1999     

Three-dimensional contrast-enhanced MRI using an intravascular contrast agent for detection of traumatic intra-abdominal hemorrhage and abdominal parenchymal injuries: an experimental study

The aim of this study was to compare the performance of 3D MRI in conjunction with an intravascular contrast agent to spiral contrast-enhanced CT, regarding the detection of abdominal parenchymal injuries as well as peritoneal hemorrhage in an animal model. Liver and kidney injuries were created surgically in six female pigs under general anesthesia. All pigs underwent contrast-enhanced spiral CT and 3D MR imaging following administration of an intravascular contrast agent (NC100150 Injection). Two readers rated their confidence independently on MR and CT data sets using a five-point scale for the presence of organ injury and hemoperitoneum. Autopsy findings served as standard of reference. Sensitivity and specificity for MR in detecting hepatic and renal injuries as well as hemoperitoneum was 100 %. Computed tomography was less accurate with sensitivity and specificity values of 90 and 94 %, respectively. Receiver operating characteristics (ROC) analysis revealed a higher confidence when interpretation was based on MR images. In an animal model 3D MR imaging in conjunction with an intravascular contrast agent proved highly accurate in detecting and localizing parenchymal injuries to the upper abdomen as well as in detecting intraperitoneal blood collections. Received: 4 November 1999, Revised: 5 May 2000, Accepted: 9 May 2000     

Blueberry juice used per os in upper abdominal MR imaging: composition and initial clinical data

The aim of this study was to evaluate the use of a commercially available blueberry juice (BJ) both as a positive and negative oral contrast agent and to present the exact contents of paramagnetic ions. The concentration of Mn and Fe were determined in tinned myrtilles in syrup (atomic absorption). Nine healthy volunteers and 12 patients (age range 20–65 years) were examined using a 1-T MR scanner before and after per os administration of 430 ml of BJ. A qualitative analysis of signal alterations in the stomach, duodenum, and proximal small intestine was performed. In addition, a quantitative analysis was assessed in terms of signal-to-noise ratio calculation. The mean concentration ( ×± SD) of the ions found in the content of the three cans were 3.3 ± 0.4 μg/g for iron and 20.6 ± 2.6 μg/g for manganese. Based on the qualitative evaluation, signal alteration on T1-weighted images after administration of BJ was statistically significant in the stomach and duodenum, but not in the proximal small bowel. Signal alteration on T2-weighted images was not statistically significant in any part of the gastrointestinal tract. The quantitative analysis of the T1- and T2 shortening showed that BJ is efficient with only T1-weighted sequences, and this applied to the stomach, duodenum, and proximal small bowel. Blueberry juice can be used as an oral contrast agent in upper abdominal MR for T1-weighted imaging. Received: 7 September 1999; Revised: 29 November 1999; Accepted: 16 February 2000     

颈静脉孔区肿瘤的CT和MRI诊断

目的：探讨CT和MRI对颈静脉孔区肿瘤的诊断及鉴别诊断。方法：回顾性分析了经手术病理证实的34例颈静脉孔区肿瘤的CT和MR影像资料,其中包括颈静脉球瘤12例,神经鞘瘤10例,转移瘤3例,脑膜瘤2例,神经纤维瘤、脊索瘤、软骨瘤、软骨肉瘤、纤维脂肪瘤、纤维血管瘤和先天性囊肿各1例。CT检查21例,其中15例作增强扫描。MRI检查31例,其中24例加作MR增强扫描。结果：肿瘤内纡曲流空的血管即“椒-盐”征是颈静脉球瘤的特征性MRI表现。神经鞘瘤易发生囊变,注射对比剂后肿瘤中度强化。转移瘤骨质破坏不规则。脑膜瘤增强扫描可见脑膜“尾巴”征。软骨瘤和软骨肉瘤可见明显钙化。结论：CT与MRI相结合能更全面地为临床提供诊断、鉴别诊断及治疗所需要的信息,为治疗方法的选择提供可靠的依据。     

CT evaluation of appendicitis and diverticulitis. Part II: Diverticulitis

CT has become the primary imaging modality for evaluation of possible diverticulitis. In studies of patients taken to surgery for suspected diverticulitis without first undergoing CT, 25–33 % of resected specimens show no inflammation. The overall accuracy of CT in establishing or excluding the diagnosis is between 84 and 99 %. In patients without diverticulitis, an alternative diagnosis is seen in 50–58 % of cases. The appearance of carcinoma with perforation and diverticulitis may be the same, and, as a result, the degree of certainty in the diagnosis should be stated. Techniques include use of either oral and intravenous contrast or rectally administered contrast. No case of colonic perforation due to rectally administered water-soluble contrast for CT has been reported, although there have been cases of perforation using barium and fluoroscopy. All techniques scan the entire abdomen and pelvis since there are frequent alternative diagnoses seen beyond the area of initial pain.     

MRI in the diagnosis of small bowel disease: use of positive and negative oral contrast media in combination with enteroclysis

The aim of the study was to evaluate the additional findings of MRI following small bowel enteroclysis and to compare the efficacy of negative and positive intraluminal contrast agents. Fifty patients with inflammatory or tumorous small bowel disease were investigated by small bowel enteroclysis and consecutive MRI using breathhold protocol (T1-weighted fast low-angle shot, T2-weighted turbo spin echo). Patients were randomly assigned to either receiving a positive oral (Magnevist, Schering, Berlin, Germany) or a negative oral MR contrast media (Abdoscan, Nycomed, Oslo, Norway). The pattern of contrast distribution, the contrast effect, presence of artifacts, as well as bowel wall and extraluminal changes, were determined and compared between the contrast type using Fischer's exact test. Sensitivity, specificity, and diagnostic accuracy for MRI and enteroclysis were calculated. Twenty-seven patients had clinically proven Crohn's disease and two patients surgically proven small bowel tumours. Magnetic resonance imaging had important additional findings as abscesses and fistulae in 20 patients. Surgically compared sensitivities were 100 and 0 % for MRI and enteroclysis, for the detection of abscesses, and 83.3 and 17 % for the diagnosis of fistulae, respectively. Bowel wall thickening was more reliably detected with use of positive oral contrast media without intravenous enhancement (p < 0.001), whereas postcontrast negative oral contrast media allow for a superior detection (p < 0.001). T2-weighted sequences were necessary with use of negative oral contrast media, because loop abscesses may be masked. Magnetic resonance imaging should be performed in all patients with suspicion of extraintestinal complications, because the complications are more reliably detected by MRI. Negative oral contrast media show advantages with the use of intravenous contrast but can mask loop abscesses using only T1-weighted imaging. Received: 5 March 1999; Revised: 21 September 1999; Accepted: 3 February 2000     

The use of advanced imaging for appendicitis in children

Improved resolution of late-generation CT and US technology has fostered an increased reliance on imaging for the preoperative diagnosis or exclusion of appendicitis. Both modalities have been shown to have a high accuracy rate, but certain diagnostic challenges persist. CT has largely replaced US for the diagnosis of appendicitis in adults, but the modality of choice is less clear in children. US is usually more easily and rapidly performed in young patients, obviating the need for contrast administration and sedation. Ionizing radiation exposure is avoided with US. Assessment of physical signs and symptoms can be achieved while performing US, an advantage over CT. However, US is best interpreted during performance of the examination, and thus CT is often favored when the interpreter is in a remote location. Strategies using limited CT to follow an indeterminate US show high diagnostic accuracy. This article discusses the controversy surrounding the optimal imaging approach to acute abdominal pain in children and illustrates some of the challenges encountered with US and CT for the evaluation of appendicitis.     

Mediastinal myelolipoma: CT and MRI appearances

A 72-year-old man presented with a mediastinal mass on chest radiograph. Computed tomography and MR imaging showed that the mass consisted of both fatty and small nodular soft tissue components, highly suggestive of an extramedullary hematopoiesis or a myelolipoma. A CT-guided needle biopsy was next performed and confirmed the diagnosis. We discuss the CT and MR imaging appearances of this tumor and usefulness of a CT-guided needle biopsy to avoid surgery in asymptomatic patients. Received: 8 March 1999; Revised: 23 June 1999; Accepted: 25 June 1999     

Multifocal nodular fatty infiltration of the liver mimicking metastatic disease on CT: imaging findings and diagnosis using MR imaging

The aim of this study was to describe the MR appearance of multifocal nodular fatty infiltration of the liver (MNFIL) using T1-weighted in-phase (IP) and opposed-phase (OP) gradient-echo as well as T2-weighted turbo-spin-echo sequences with fat suppression (FSTSE) and without (HASTE). Magnetic resonance imaging examinations at 1.5 T using T1-weighted IP and OP-GRE with fast low angle shot (FLASH) technique, and T2-weighted FSTSE, T2-weighted HASTE of 137 patients undergoing evaluation for focal liver lesions were reviewed. Five patients were identified in whom CT indicated metastatic disease; however, no liver malignancy was finally proven. Diagnosis was confirmed by biopsy (n = 3), additional wedge resection (n = 1) or follow-up MRI 6–12 months later (n = 5). Regarding the identified five patients, the number of focal liver lesions was 2 (n = 2) and more than 20 (n = 3). The MR imaging characteristics were as follows: OP-image: markedly hypointense (n = 5); IP image: isointense (n = 2) or slightly hyperintense (n = 3); T2-weighted FSTSE-image: isointense (n = 5); T2-weighted HASTE image isointense (n = 1); slightly hyperintense (n = 4). On OP images all lesions were sharply demarcated and of almost spherical configuration (n = 5). Further evaluation by histology or follow-up MR imaging did not give evidence of malignancy in any case. Histology revealed fatty infiltration of the liver parenchyma in three patients. Magnetic resonance follow-up showed complete resolution in two patients and no change in three patients. Multifocal nodular fatty infiltration can simulate metastatic disease on both CT and MR imaging. The combination of in-phase (IP) and opposed-phase (OP) gradient-echo imaging can reliably differentiate MNFIL from metastatic disease. Received: 15 September 1999 Revised: 3 February 2000; Accepted: 7 February 2000     

Postoperative findings following the Whipple procedure: determination of prevalence and morphologic abdominal CT features

This study was conducted to determine characteristic CT findings following the Whipple procedure and to evaluate the usefulness of CT in predicting tumor recurrence. Eighty-four postoperative abdominal CT scans and medical records of 43 patients were retrospectively reviewed. Perioperative histopathologic examinations revealed malignancy in 32 patients (74.4 %). Time interval between surgery and CT varied from 13 days to 6 years and 7 months. Common postoperative findings were unopacified anastomotic bowel loops in the porta hepatis (n = 69 scans), perivascular cuffing (n = 42 scans), pneumobilia (n = 40 scans), dilated intrahepatic bile ducts (n = 22 scans), reactive lymphadenopathy (n = 21 scans), and transient fluid collections (n = 20 scans). Postoperative complications were detected on 17 CT scans (20.2 %): generalized ascites (n = 8 patients), deep abscesses (n = 3 patients), wound abscess (n = 1 patient), pancreatitis (n = 1 patient), and pseudomembranous colitis (n = 1 patient). Tumor recurrence appeared in 15 patients (46.8 %) after a mean postoperative period of 11 months (1 month to 3 years): local (9 of 15), regional lymph nodes (9 of 15), and liver metastasis (8 of 15). Detection of generalized ascites more than 30 days after surgery was associated with tumor recurrence in 6 of 6 patients (100 %). Diffuse ascites (> 30 days after surgery) behaved as an early predictive sign of tumor recurrence. In our series CT accuracy for detecting recurrent tumor with CT was 93.5 %. No predilection site for disease recurrence could be determined. Received: 1 February 1999; Revised: 15 April 1999; Accepted: 19 April 1999     

Correlation of MRI and CT findings with histopathology in hepatic angiomyolipoma

Hepatic angiomyolipomas are rare and often mimic other liver tumors. The aim of our study was to describe the CT and MRI findings and to correlate imaging features with histopathology. The CT and/or MR images were available for retrospective analysis in seven patients. Patients had non-enhanced as well as enhanced CT (n = 6) or MRI (n = 4) before and after administration of Gd-DTPA (n = 2) or MnDPDP, a liver specific contrast agent, (n = 3). In three patients CT and MRI did not detect fat, and in two patients the angiomyolipomas were also histopathologically devoid of fat. Vascularity ranged from hypervascular (n = 4) with arteriovenous shunts (n = 1) to equal (n = 1) or less (n = 2) postcontrast enhancement compared with the normal liver parenchyma. No uptake of the liver specific contrast agent, MnDPDP, was observed (n = 3). Predominantly, CT and MRI did not include angiomyolipoma in the differential diagnosis, and the initial histopathological evaluation was inconclusive in more than half the cases. Hepatic angiomyolipomas frequently manifest as solitary well-circumscribed heterogeneous masses in patients with no underlying liver disease or elevation of serum tumor markers. If present, the demonstration of intratumoral fat is helpful in the diagnosis of angiomyolipoma. The final diagnosis can be obtained by immunohistochemistry.     

Small volume hyperosmolar abdominal CT in acute small bowel obstruction

Purpose: Identification of the degree of small bowel obstruction (SBO) is helpful in patient management decisions since the treatment of partial SBO is nonoperative, whereas the treatment of complete SBO requires surgical intervention. We describe a technique providing the benefits of CT and enteroclysis together, which allows the radiologist to determine the degree of the SBO and thereby to distinguish partial from complete SBO. Methods and materials: Abdominal CT scans were performed on 21 patients. Patients were given 200 ml concentrated oral contrast medium. Serial radiographs followed the progression of contrast at 1, 3, and 5 h in order to optimize the timing of the abdominal CT. A partial SBO was diagnosed if the oral contrast reached the colon at or before the 5-h film, and a complete SBO if the oral contrast did not reach the colon by the 5-h abdominal radiograph. The CT was performed when the contrast reached the colon or after the 5-h film. Results: CT findings demonstrated complete obstruction in eight patients, all of whom required surgical treatment. Partial SBO was demonstrated in 13 patients. Ten of the 13 patients with partial SBO had an uncomplicated transition zone, probably due to adhesions, and were treated medically. Nine of these patients were managed with nasogastric tube decompression and were discharged without surgical intervention. One patient failed to respond to a 12-h course of nasogastric tube decompression and underwent lysis of adhesions. Three of the 13 patients had a complicated transition zone, due to an intussusception and two hernias, which were responsible for the SBO. Two were treated surgically and one medically. Conclusion: The use of small-volume hyperosmolar abdominal CT allows the radiologist to determine the degree of the SBO. This additional information is very useful in patient management because uncomplicated partial SBO is often treated successfully via tube decompression, whereas complete SBO requires surgical intervention.     

CT and MR findings in neoplastic perineural spread along the vidian nerve

The aims of this article are to describe the findings of perividian tumor spread and to compare the accuracy of MRI and CT in diagnosing perineural metastasis along the vidian nerve. Moreover, the frequency of perividian metastasis in patients with head and neck cancer was evaluated. The CT and MR examinations of 98 consecutive untreated patients with histologically proven head and neck cancer were retrospectively reviewed. We considered as criteria for perineural tumor spread along the vidian nerve the following CT and MR findings: For CT (a) enlargement of the pterygoid canal, (b) erosion of its bony wall, and (c) obliteration of its normal fatty content; and for MR (a) enlargement of the vidian nerve, (b) enhancement of the nerve, and (c) obliteration of fat, particularly in the anterior part of the pterygoid canal. Ten patients met the selected criteria for perineural metastasis, which was bilateral in 3 patients, with a total of 13 vidian metastases. The CT scans demonstrated unilateral involvement of the vidian nerve in 9 patients. The MRI scans showed 13 perineural metastases. In 3 patients MR scans demonstrated involvement of four vidian nerves that appeared normal on CT examinations. The diagnostic difference between CT and MRI was statistically significant (Fisher's exact test; p = 0.04). Perineural spread along the vidian nerve is an event more frequent than previously reported and must be investigated with a careful imaging technique. Although a major limitation of our study is the lack of histological proof, the MR finding of a significant enhancement of the nerve, whether enlarged or normal in size, could be considered very suggestive of this kind of metastatic spreading, particularly if associated with simultaneous involvement of the neighboring structures (pterygopalatine fossa, foramen lacerum, trigeminal branches, etc.). Received: 5 January 1999; Revision received 11 May 1999; Accepted: 17 June 1999     

Acute pulmonary embolism: visualization of high attenuation clot in the pulmonary artery on noncontrast helical chest CT

Helical CT of the thorax is frequently utilized for the evaluation of chest pain or shortness of breath affecting the emergency patient. To improve diagnostic accuracy, thoracic CT examinations are frequently tailored to address specific conditions. Although tailored protocols may enhance diagnostic accuracy, implementing the wrong protocol could result in a misdiagnosis. The proper protocol choice may particularly difficult in the emergency patient due to the nonspecific nature of many chest pain syndromes. Recently, helical CT has been used for the evaluation of suspected pulmonary embolism (PE). Demonstration of an intravascular filling defect surrounded by contrast-enhanced blood is diagnostic of PE. However, because the clinical presentation of PE is frequently nonspecific, awareness of the many potential imaging manifestations of PE is important. Therefore, we present the rare circumstance of high-attenuation clot visible within the pulmonary arteries on noncontrast helical CT; PE was confirmed after the administration of iodinated contrast medium.     

Radiographically occult ureteral calculi in an HIV-positive child undergoing indinavir therapy

Helical CT has been shown to be a sensitive and specific tool for the rapid diagnosis of obstructing urinary tract calculi. AIDS patients taking the protease inhibitor indinavir, however, can develop urinary tract calculi that are invisible on CT. We present a case of a 9-year-old HIV-positive girl who developed acute ureteral obstruction while taking indinavir. Helical CT after the administration of intravenous contrast demonstrated signs of ureteral obstruction although no obstructing calculus was visualized. This case demonstrates that obstructing ureteral calculi secondary to indinavir therapy may not be visualized with helical CT, unlike nearly all other obstructing calculi. When secondary signs of obstruction are seen in these patients, the radiologist must have a high index of suspicion for urinary tract calculi even without direct visualization of a stone.     

Characterization of unifocal liver lesions with pulse inversion harmonic imaging after Levovist injection: preliminary results

The aim of this study was to evaluate capabilities of pulse inversion harmonic imaging (PIHI) in characterization of unifocal liver lesions. We evaluated with PIHI (HDI5000, ATL, Bothell, Wash.) and spiral CT 46 consecutive patients with a single liver lesion identified by fundamental US [7 hepatocellular carcinomas (HCC), 2 cholangiocarcinomas, 7 focal nodular hyperplasias (FNH), 17 hemangiomas and 13 metastases]. The PIHI was performed before and 30 s, 2 and 4 min after bolus administration of Levovist (2.5 g, 300 mg/ml). Scans were digitally stored and reviewed using a dedicated software. Hepatocellular carcinoma was hyperechoic on 30-s scan, and hypoechoic (n = 5) or isoechoic (n = 2) on 2-min scan. Cholangiocarcinoma had inhomogeneous persistent enhancement. Focal nodular hyperplasia was hyperechoic (n = 5) or isoechoic (n = 2) on 30-s scan, hyperechoic (n = 4), isoechoic (n = 2) or slightly hypoechoic (n = 1) on 2-min scan. Large hemangioma revealed peripheral enhancement on 30-s scan which extended centripetally on 2-min scan. Small hemangioma appeared isoechoic on 2-min scan in all but two cases in which they were hypoechoic on 2-min scans and hyperechoic on 4-min scan. Metastasis was hypoechoic on all scans, 70% with rim enhancement. Similar changes in enhancement pattern have been observed at spiral CT. The 30-s and the 2-min scans revealed a conclusive importance in characterization of HCC, cholangiocarcinoma, and large hemangioma. The 2-min scan often furnished enough information for characterization of small hemangioma and metastasis. The 4-min scan allowed characterization of two hemangiomas which appeared hypoechoic on 2-min scans. In the other cases it did not provide further information. Diagnosis of FNH is usually reached with Colour Doppler US; PIHI should be used when colour Doppler is biased by artefacts or when colour Doppler findings are not characteristic. Our results seem to show that PIHI could be a valuable alternative diagnostic approach to spiral CT for unifocal liver lesion characterization. This hypothesis needs to be confirmed with an increased number of lesions.     

Should an MR scan be performed routinely after a normal clearance CT scan in the trauma patient? Experience with 59 cases

Magnetic resonance (MR) imaging is not routinely used to exclude ligamentous and other soft tissue injury in the unconscious trauma patient. In order to determine the frequency and types of soft tissue injuries detected by MR imaging but not by computed tomography (CT), we performed a retrospective investigation comparing the MR findings in 59 trauma patients, either alert or unconscious, who previously had undergone a negative clearance multislice CT study of the cervical spine. Six patients had abnormalities not identified on the CT studies, including four cases of ligamentous injury.