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Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ©RSNA, 2017.

Congenital extrahepatic porto systemic shunt (CEPS) is a rare condition in which the porto mesenteric blood drains into a systemic vein, bypassing the liver through a complete or partial shunt. It is commonly associated with multiple congenital anomalies. A diagnosis of Abernethy malformation is made by non-invasive cross-sectional imaging techniques such as Doppler ultrasound, CT or MRI, which show the shunt and intrahepatic portal vein branches. We report a case presenting with psychological issues, systemic hypertension, upper extremity deformities, liver lesions and portal hypertension. Usually the patients are diagnosed in childhood, in our case the patient is a middle aged woman. This case report shows the importance of imaging in diagnosis of this condition and presentation of the patient with portal hypertension which is rare.DOI: http://dx.doi.org/10.3126/njr.v3i2.9622 Nepalese Journal of Radiology Vol.3(2)July-Dec, 2013: 97-102

Adrenal collision tumors (ACTs) refer to coexistence of two adjacent, but histologically distinct neoplasms involving the adrenal gland without histologic admixture at interface. ACTs include adenoma with myelolipoma, adenoma with metastases, hemangioma with adenoma, and adrenocortical carcinoma with myelolipoma. In addition, hemorrhage into a pre-existing adrenal mass can mimic an ACT, and it is important to differentiate these two pathologies. Accurate characterization of ACTs is difficult, but critical, for correct staging of patients with malignancies and to guide percutaneous biopsy. Magnetic resonance imaging (MRI) and multidetector computed tomography imaging techniques may depict different tumor components separately; however, biopsy may be required in selected patients for confirmation. [18F]Fluorodeoxyglucose-positron emission tomography (PET) shows increased uptake in the malignant component of ACTs, and guides percutaneous biopsy. Even in patients requiring percutaneous biopsy for a definite diagnosis, imaging findings can help in guiding the appropriate component to be biopsied. Knowledge of imaging findings of different ACTs and their mimics on MRI, computed tomography, and PET help in optimal patient management.

Hemangiomas are a radiologist's dream lesions because they allow a confident diagnosis most of the time. However, within the abdomen, hemangiomas may occur in such atypical locations and can have such unusual features that they cause significant diagnostic dilemma and may end up being excised surgically. The literature is replete with isolated case reports of atypical hemangiomas in the abdominal cavity, and, to our knowledge, so far, there is no comprehensive review. We present, in this article, a pictorial review of a gamut of uncommon hemangiomas and hemangiomatosis syndromes. Knowledge of these rare types can help in limiting diagnostic errors and increase the confidence of radiologists, thus avoiding unnecessary surgeries.

Acute complications arising in abdominopelvic malignancies represent a unique subset of patients presenting to the emergency room. The acute presentation can be due to complications occurring in the tumor itself or visceral or vascular structures harboring the tumor. Multidetector computed tomography (MDCT) is the investigation of choice in the workup of these patients and enables appropriate and timely management. Management of the complication depends primarily on the extent of the underlying malignancy and the involvement of other viscera. The purpose of this article is to depict the imaging features of these complications on MDCT.

The recent proliferation of multi–detector row computed tomography (CT) has led to an increase in the creation and interpretation of images in planes other than the traditional axial plane. Powerful three-dimensional (3D) applications improve the utility of detailed CT data but also create confusion among radiologists, technologists, and referring clinicians when trying to describe a particular method or type of image. Designing examination protocols that optimize data quality and radiation dose to the patient requires familiarity with the concepts of beam collimation and section collimation as they apply to multi–detector row CT. A basic understanding of the time-limited nature of projection data and the need for thin-section axial reconstruction for 3D applications is necessary to use the available data effectively in clinical practice. The axial reconstruction data can be used to create nonaxial two-dimensional images by means of multiplanar reformation. Multiplanar images can be thickened into slabs w...

Radiofrequency (RF) thermal ablation has shown promise as a technique for treating inoperable solid tumors involving the liver, kidney, adrenal gland, and lung. However, like all other imaging-guided interventional procedures, RF ablation involves some element of risk. Varying degrees of complications can be expected, depending on factors such as the organ site and the aggressiveness of the procedure. General complications of RF ablation may be related to either imaging-guided electrode placement (eg, bleeding, infection, tumor seeding, pneumothorax) or thermal therapy (eg, nontarget thermal damage, grounding pad burns). Liver and renal-adrenal ablation may be associated with organ-specific complications. A fundamental understanding of RF ablation principles, along with adequate operator training and experience and familiarity with both thermal ablation and the broad spectrum of postablation complications, are necessary to maximize the safety and efficacy of this procedure. The standard of care for decreasing the morbidity of complications consists of prevention (including careful patient selection), early detection, and prompt, appropriate treatment.

We conducted this study to determine the spectrum of CT findings of tumor recurrence after radiofrequency ablation of primary and secondary malignant hepatic tumors.Twenty-five patients, 10 with hepatocellular carcinoma (HCC) and 15 patients with metastases who developed tumor recurrence after radiofrequency ablation of hepatic neoplasms, formed the study population. Three observers reviewed the CT scans of these patients and evaluated the location (local intrahepatic, remote intrahepatic, or extrahepatic) of all recurrent lesions and the morphology and enhancement characteristics of local intrahepatic recurrences.Local intrahepatic recurrences were seen in nine patients (90%) and 11 patients (73%); remote intrahepatic recurrences, in five patients (50%) and seven patients (45%); and extrahepatic recurrences, in zero and six patients (40%) with recurrent HCC and recurrent metastases, respectively. Of the 12 nodules of local intrahepatic recurrences in HCC and the 24 in metastases, the patterns of local intrahepatic recurrences were of nodular, halo, and gross enlargement types in eight (67%) and nine (38%), four (33%) and six (38%), and zero and nine (37%) nodules in HCC and hepatic metastases, respectively. The number of local intrahepatic recurrent lesions enhancing in the arterial phase was significantly greater in HCC.Tumor recurrences occurred at intra- and extrahepatic sites after radiofrequency ablation of hepatic neoplasms. The local intrahepatic recurrences appeared in three patterns: nodular, halo, or gross enlargement. The sites of recurrence and the morphologic patterns of local intrahepatic tumor recurrence differed between primary and secondary hepatic neoplasms.

Twenty asymptomatic volunteers underwent helical computed tomographic (CT) cholangiography 10-12 hours after ingesting iopanoic acid. Three observers assessed the images for the extent of bile duct visualization and image quality. The common bile duct and common hepatic duct were adequately visualized in 19 (95%) subjects. Helical CT cholangiography with oral cholecystographic contrast material is feasible and deserves further clinical studies.

To determine the frequency and CT imaging spectrum of mesenteric, omental, and retroperitoneal edema in patients with cirrhosis.Eighty patients were identified with liver cirrhosis and no other cause of edema. Five radiologists jointly reviewed the abdominal CT scans of these patients to assess, by majority decision, the presence, severity, distribution, and configuration of mesenteric edema and the presence of omental and retroperitoneal edema. Subcutaneous edema, ascites, pleural effusion, splenomegaly, varices, portal venous thrombosis, and serum albumin levels were also documented.Mesenteric edema was present in 69 (86%) patients. Mesenteric edema occurred alone in 26 (38%) and with omental or retroperitoneal edema in 40 (58%) of the 69 patients with edema. No patient had omental or retroperitoneal edema alone. Mesenteric edema was mild in 51 (74%) and moderate to severe in 18 (26%), patchy in 47 (68%) and diffuse in 22 (32%), purely infiltrative in 60 (87%) and infiltrative with superimposed masslike nodules in nine (13%) patients. These parameters had significant associations among themselves and with ascites, pleural effusions, subcutaneous edema, and low mean serum albumin levels but not with splenomegaly or varices.Mesenteric, omental, and retroperitoneal edema occur commonly in patients with cirrhosis. The appearance of mesenteric edema varies from a mild infiltrative haze to a severe masslike sheath that engulfs the mesenteric vessels.

Purpose We retrospectively evaluated sonographic findings in 946 cases of gallstones to determine whether the false-negative rate for gallstone detection by sonography has decreased as a result of technologic advances over the past 15 years. Methods We reviewed preoperative sonographic reports, operative notes, and pathologic reports for 614 women and 332 men (ages 22–78 years) seen over a 2.5-year period and compared sonographic findings with surgical pathologic findings after cholecystectomy. Sonograms for patients whose gallstones were missed on sonography were reviewed by 3 board-certified radiologists. Results Preoperative sonography of the gallbladder accurately predicted the presence of gallstones in 934 cases (98.7%). Gallstones were not identified by sonography in the remaining 12 cases. In those cases, sonography revealed polyps in 5, sludge in 5, sludge plus a polyp in 1, and neither stones nor polyps in 1. Thus, the false-negative rate was 1.3%. Conclusions Despite improvements in sonographic technology, detection of small gallstones remains difficult in some cases. Adherent gallstones can mimic gallbladder polyps. Our false-negative rate for detection of gallstones was no different from that in earlier studies. © 1999 John Wiley & Sons, Inc. J Clin Ultrasound 27:117–121, 1999.

To retrospectively determine the computed tomographic (CT) signs associated with diverticulitis or colon cancer, and to prospectively apply these signs in the differentiation of these diseases.Fifty-eight CT scans in cases of proved diverticulitis (n = 27) or colon cancer (n = 31) were evaluated retrospectively by radiologists (blinded to the proved diagnosis) for the presence or absence of previously reported CT findings. These findings were correlated with the pathologic or final clinical diagnosis. The retrospective findings were applied in a prospective evaluation with a new set of 72 CT scans. The same five radiologists rendered a diagnosis according to a five-point confidence scale from definitely benign to definitely malignant. Individual and consensus readings were correlated with the final diagnosis.Retrospectively, pericolonic inflammation (P.01) and segment involvement greater than 10 cm (P.012) were the most significant findings for diverticulitis; pericolonic lymph nodes (P.0001) and luminal mass (P.003) were the most significant findings for colon cancer. Prospectively, an unequivocal diagnosis was made correctly in 16 (40%) of 40 cases of diverticulitis and 21 (66%) of 32 cases of colon cancer.When there are no pericolonic lymph nodes adjacent to a segment of colonic wall thickening, with pericolonic inflammatory changes, the most likely diagnosis is diverticulitis. When pericolonic lymph nodes are present, with or without pericolonic edema, the most likely diagnosis is colon cancer.

The aim of this article is to present pictorially the spectrum of appearances of the appendix and appendicitis on CT. The images presented were selected from the database of our hospitals. The various appearances of the normal appendix on CT are shown. Appendicitis can be divided into four categories on the basis of CT findings. Examples of each category are shown.

There is an increasing incidence of both intra- and extra-thoracic manifestations of tuberculosis, in part due to the AIDS epidemic. Isolated tubercular involvement of the solid abdominal viscera is relatively unusual. Cross-sectional imaging with ultrasound, multidetector computed tomography (CT), and magnetic resonance imaging (MRI) plays an important role in the diagnosis and post treatment follow-up of tuberculosis. Specific imaging features of tuberculosis are frequently related to caseous necrosis, which is the hallmark of this disease. However, depending on the type of solid organ involvement, tubercular lesions can mimic a variety of neoplastic and nonneoplastic conditions. Often, cross-sectional imaging alone is insufficient in reaching a conclusive diagnosis, and image-guided tissue sampling is needed. In this article, we review the pathology and cross-sectional imaging features of tubercular involvement of solid abdominopelvic organs with a special emphasis on appropriate differential diagnoses.

With the increasing use of multidetector computed tomography and dynamic magnetic resonance imaging in evaluation of liver pathologies, a variety of vascular shunts are detected in the liver. These shunts can be related to tumors or they can be nonneoplastic. Identification of these shunts can help in diagnosing an underlying condition. We classify and describe a wide spectrum of intrahepatic vascular shunts with their key imaging features. After reviewing this article, the reader should have improved ability to detect and characterize intrahepatic vascular shunts, which will help in diagnosing an underlying condition and facilitate optimal patient care.

The purpose of this article is to discuss radiation dose during CT-guided interventions and to explain how radiologists can modify technical factors to minimize radiation doses. Scanner-displayed indexes of radiation exposure that are available during the procedure will be defined to increase awareness about CT radiation dose reduction during interventional procedures.CT-guided fluoroscopic procedures are safe and effective methods of directed intervention; however, the increasing use of medical radiation is an important consideration. The appropriate use of imaging with an acceptable risk must be considered in every case. During CT-guided interventions, scanner parameters that can be used as a guide for effective dose management, including the CT dose index and dose-length product, are readily displayed. These parameters can be adjusted by modifying the longitudinal scan length, number of scans, and tube current-exposure time product (milliampere × second [mAs]). A team approach to radiation dose reduction will work the best.

Aberrant internal carotid arteries presenting as pharyngeal masses are described in the literature. Eight patients were evaluated by CT, angiography or MRI. Our studies indicated that the phyaryngeal pseudo masses were due to aberrant carotid vessels. Unlike the previous reports, in tour of our eight cases both common and internal carotid arteries were the cause of the suspected mass. Contrast-enhanced CT studies consistently demonstrated the abnormalities. MRI may be done if patients have a contraindication to intravenous iodinated contrast administration.

Benign hepatic neoplasms constitute a heterogeneous group of neoplasms with characteristic histology and variable tumor biology. Based on the cell of origin, benign hepatic neoplasms are classified into epithelial, nonepithelial, and miscellaneous categories according to the 2000 World Health Organization classification system. Benign hepatic neoplasms demonstrate a wide spectrum of imaging findings that reflect the histomorphologic changes. Some neoplasms show pathognomic imaging findings that permit accurate characterization and optimal management.

A case of pseudomyxoma peritonei with increased radionuclide uptake in the abdomen is described. The uptake of the radionuclide was confined to the omentum as confirmed by the CT study of the abdomen and pelvis. The mechanism of uptake and differential diagnosis are discussed.

This study was done to determine if the detection of pericolic lymph nodes on CT scans could be used to differentiate cancer of the colon from diverticulitis.We retrospectively evaluated 58 CT scans from 57 patients with proven diverticulitis or cancer of the colon. The CT scans were evaluated by five board-certified radiologists who were unaware of the proven diagnosis. Consensus opinions regarding the presence and size of pericolic lymph nodes were recorded. These data were correlated with the proven diagnoses to determine the correlation between the observed findings and the type of colonic abnormality. Fisher's exact test was used to determine statistical significance.Lymph nodes were seen in 22 (71%) of 31 cases of colonic cancer and in four (15%) of 27 cases of diverticulitis. The lymph nodes were 0.5-2.5 cm in short-axis diameter. We saw no difference in node size for patients with colonic cancer versus patients with diverticulitis. The nodes were most commonly located along the blood vessels in the mesenteric fat. Statistical analysis showed a significant difference (p.001) in the frequency but not in the size of nodes between the two groups of patients. The detection of nodes resulted in a diagnostic sensitivity and specificity for colonic cancer of 71% and 85%, respectively.Pericolic lymph nodes are seen much more frequently in patients with colonic cancer than in patients with diverticulitis. The detection of pericolic lymph nodes in patients suspected of having diverticulitis should raise the suspicion of underlying colonic cancer that should, in turn, prompt additional evaluation.

We performed a study to determine the correlation between the diameter of the echogenic response observed with intraoperative sonography during radiofrequency ablation of the cirrhotic liver and the mean diameter of tissue necrosis.A total of 22 intraoperative radiofrequency ablations were created in 11 cirrhotic livers. The largest diameter of the sonographically observed echogenic response surrounding and perpendicular to the radiofrequency probe was measured. The subsequent zone of necrosis observed at pathology in the hepatectomy specimens after liver transplantation was measured in three planes and compared with the measured diameter of the echogenic response.During all except three ablations, a hyperechoic region was visualized surrounding the radiofrequency probe. The diameter of the echogenic response correlated significantly with the mean diameter of necrosis (correlation coefficient, 0.84). However, the echogenic response overestimated the minimal diameter of necrosis (mean difference, 0.8 +/- 0.4 cm) in 18 of 22 ablations and underestimated the maximum diameter of necrosis (mean difference, 0.9 +/- 0.8 cm) in 16 of 22 ablations.The diameter of the echogenic response observed with intraoperative sonography during radiofrequency ablation of the cirrhotic liver correlates closely with the mean diameter of the subsequent area of tissue necrosis. However, the solitary diameter of the echogenic response as measured in our study was often greater than the smallest diameter and less than the largest diameter of the area of tissue necrosis. Therefore, the echogenic response associated with radiofrequency ablation of the cirrhotic liver should be viewed only as a rough approximation of the area of induced tissue necrosis; the final assessment of the adequacy of ablation should be deferred to an alternative imaging technique.

To determine the sensitivity, specificity, and accuracy of helical computed tomographic (CT) angiography in the detection of transjugular intrahepatic portosystemic shunt (TIPS) stenoses or occlusions.Thirty-seven patients underwent 50 helical CT angiographic examinations and, within 2 weeks of each examination, portography with measurement of the portosystemic pressure gradient. Helical CT angiograms were independently interpreted by three radiologists who were blinded to the results of portography. Results of helical CT angiography and portography were compared. Sensitivity and specificity of helical CT angiography were separately calculated for the demonstration of morphologic abnormalities and the determination of their hemodynamic significance.Of the 50 portograms, 31 (62%) demonstrated morphologic TIPS abnormalities, 24 (77%) with and seven (23%) without elevated portosystemic pressure gradients. Helical CT angiograms correctly demonstrated 30 (97%) of the 31 morphologic abnormalities and allowed correct diagnosis of 22 (92%) of the 24 hemodynamically significant abnormalities. Nineteen (38%) portograms were normal; helical CT angiograms correctly demonstrated the absence of abnormality in 17 (90%) of these cases. Sensitivity and specificity of helical CT angiography for all morphologic abnormalities were 97% and 89%, respectively, and, for hemodynamically significant abnormalities, 92% and 77%.Helical CT angiography holds promise as a screening modality for the detection of TIPS stenoses or occlusions.

To determine the frequency and patterns of gastrointestinal wall thickening at contrast material-enhanced computed tomography (CT) in patients with cirrhosis.Three radiologists retrospectively assessed the contrast-enhanced abdominal CT scans of 77 patients with cirrhosis and 100 patients without cirrhosis for gastrointestinal wall thickening from the stomach through the descending colon. The frequencies of wall thickening were determined in the cirrhosis and in the control groups and were compared by using the Fisher exact test. The segmental distribution, symmetry, and enhancement pattern were evaluated in all patients with cirrhosis and gastrointestinal wall thickening.Gastrointestinal wall thickening was seen in 49 (64%) patients with cirrhosis and in seven (7%) control subjects (P.005). The jejunum and ascending colon were the most common sites of gastrointestinal wall thickening; each was involved in 32 (42%; 95% CI: 30%, 53%) patients. The scans of 30 (61%; 95% CI: 47%, 75%) patients with gastrointestinal wall thickening showed multisegmental distribution. Gastrointestinal wall thickening was concentric and homogeneous in all patients with cirrhosis.Gastrointestinal wall thickening is common on contrast-enhanced abdominal CT scans in patients with cirrhosis. It frequently involves multiple segments. The jejunum and ascending colon are the most common sites of involvement.

We present the CT findings of three cases of primary papillary serous carcinoma of the peritoneum. All patients presented with massive ascites. CT of the abdomen and pelvis showed omental caking in all patients. The parietal peritoneum of the pelvis showed diffuse enhancement with nodular thickening in all patients. No calcification was noted in the omental and parietal peritoneal masses, although psammoma bodies were present microscopically in one case. The ovaries were normal in size but showed a fine enhancing surface nodularity similar to the pelvic peritoneum. The CT findings of primary papillary serous carcinoma of the peritoneum are nonspecific, but this diagnosis should be considered when peritoneal carcinomatosis is seen on CT with normal-sized ovaries in the absence of other primary malignant neoplasms.

Shunt dysfunction due to draining hepatic vein and/or stent stenosis is a common long-term complication of transjugular intrahepatic portosystemic shunts (TIPS). Currently, Doppler sonography is the preferred modality for routine screening of TIPS for the detection of these complications. However, this method is time-consuming, highly operator-dependent, and difficult to perform because of the anatomic attributes of the cirrhotic liver. The use of helical CT angiography (HCTA) for imaging TIPS has been recently described. HCTA of TIPS is performed after a rapid i.v. injection of a bolus of low osmolality contrast medium, followed by helical data acquisition of the region of the shunt using thin sections. The data are then reprocessed a overlapping intervals and various reformations are obtained. Preliminary reports show the sensitivity and specificity of the helical CT angiography to be comparable with Doppler sonography.

Recent advances in radiology have greatly increased the ability to make highly accurate diagnosis. Biopsy of many commonly seen lesions is no longer performed as the radiological findings are pathognomonic. This gives rise to the concept of ‘virtual biopsy’, a term coined on the lines of other imaging techniques such as virtual colonoscopy. Virtual biopsy is not a new imaging technique but a new concept which refers to the use of existing imaging modalities to evaluate the morphological features of tumors and arriving at a non-invasive diagnosis with a high degree of confidence obviating the need for true biopsy. Elements of virtual biopsy have already been incorporated into some evidence-based guidelines, and it is expected that with further technological advancements, an increasing number of tumors may be diagnosed and managed accordingly. A wider acceptance of virtual biopsy could further reduce the need for invasive biopsies and its attendant costs and risks. In this review article, we use index cases to further emphasize this concept.

A retrospective computed tomography evaluation of proved low-attenuation splenic lesions in nontraumatic cases was done. Computed tomography was able to distinguish cystic from solid lesions. Although computed tomography examination is sensitive in the detection of low-attenuation lesions, the computed tomography findings alone are not helpful in differentiation of different low-attenuation lesions. Associated computed tomography findings in other organs and clinical findings are more helpful than the size, shape, and computed tomography attenuation of the lesions. Splenic lesions may be the only metastatic manifestation in some cancer patients. A thin needle aspiration may be done to document the nature of the pathologic lesion in problematic cases.

A case of perinephric abscess with renal cell carcinoma is presented. Hematuria is uncommon in cases of perinephric abscess. When hematuria is present in a patient with perinephric abscess further evaluation is necessary to rule out an associated malignant process.

The incidence of renal fascial thickening in pancreatic inflammatory disease was evaluated by computed tomography. A total of 71 cases including chemical, acute complicated, and acute and chronic uncomplicated pancreatitis were retrospectively evaluated for thickening of the renal fascia. Renal fascial thickening is demonstrated in the majority of patients with complicated and uncomplicated pancreatitis. It is not demonstrated in cases of chemical pancreatitis. Renal fascial thickening is nonspecific and seen with inflammatory, malignant, and traumatic processes, but it is a valuable adjunctive sign of pancreatic inflammatory disease.

A comparison of hepatic computed tomography (CT) before and after administering intravenous contrast material was performed 85 times on 81 patients suspected of having hepatic mass lesions. Both pre- and postcontrast computed tomography were sensitive and specific in over 88% of cases, with no statistical difference in accuracy between the techniques. However, postcontrast scans were generally preferred because of increased diagnostic confidence and improved characterization of associated abnormalities. The recent advent of rapid sequential scanning after intravenous administration of a large volume of contrast material seems to further improve diagnostic confidence. When high-resolution CT equipment is used, postcontrast CT alone is the preferred method for CT evaluation of patients with suspected liver lesions.

In the identification of discrete and conglomerate retroperitoneal lymph node masses, MRI and CT performed equally well. No specific MRI characteristics were identified.

The classic radiographic appearance of pulmonary aspergilloma is a solid, round, often mobile intracavitary mass. We describe an unusual “cavity-incavity” appearance seen on conventional roentgenograms and computed tomography studies in two patients with confirmed pulmonary aspergilloma. We are not aware of any previous report describing such appearance based on literature search.

CT examinations of four proven abdominal abscesses with enteric communications are reported. All the patients received oral contrast (3% Gastrografin solution). Three patients recieved rectal contrast. The patient who did not receive rectal contrast had a prior abdominoperineal resection. Contrast material was administered intravenously unless there was a contraindication or a suspected enteric vesical fistula. A representative case is described.

In Reply.— I agree with the comments of Drs Sarwar and Naseem. Unfortunately, MRI is done in patients with no previous radiographic studies, such as CT. Magnetic resonance imaging has, in my opinion, limited use in the evaluation of calcifications as they appear as low-intensity signals. Plain roentgenograms may demonstrate the abnormality better than MRI studies. Computed tomography due to the axial display of the ligamentum flavum localizes the calcifications well. Dr Olson's comments are well taken. Ligamentous ossification involving the ligamentum flavum or posterior longitudinal ligament contributes to spinal stenosis. Trauma, vascular lesions, and a tendency to ossify ligaments, such as in diffuse idiopathic skeletal hyperostosis (Forestier's disease), are some of the causes of ossification. Ossification may be an associated radiological abnormality, as in patients with thoracic posterior longitudinal ligament ossification. 1