Postcontrast Computed Tomography Research Articles

Computed tomography of superior mesenteric vein thrombosis following appendectomy.

During a 5-year period, superior mesenteric vein (SMV) thrombosis was detected with computed tomography (CT) in six patients shortly after an appendectomy. No sign of SMV was present at appendectomy, and a period of more than 2 weeks free of clinical symptoms had elapsed between the appendectomy and the onset of the SMV thrombosis. In four cases, the appendicitis was complicated. These patients had nonspecific signs and symptoms, although two of them had elevation of blood hepatic enzyme levels. In all cases, postcontrast CT demonstrated enlargement of the SMV, with well-defined enhancement of the vascular wall and an intraluminal clot. In one case, CT showed extension of the thrombus to the portal vein with the presence of low-attenuation areas in the liver, consistent with hepatic infarcts. Two patients had predisposing diseases: idiopathic hypersplenism in one case and chronic hepatic disease in the other. SMV thrombosis is a possible complication of appendicitis, and early appendectomy in appendicitis can prevent this complication. Moreover, as in any abdominal surgery, early appendectomy may be complicated by thrombosis of the SMV, thus creating problems of postoperative diagnosis. The complication is more frequent when the initial operation is performed under difficult conditions (peritonitis), or when the patient presents with a coagulopathy. CT is useful in the diagnosis of SMV thrombosis, thus leading to early management with anticoagulant therapy, with a view to avoiding complications such as intestinal ischemia, portal vein thrombosis, and hepatic infarction.

Clinical significance of non-Hodgkin's lymphoma with an irregular, non-contrast-enhanced area

An irregular, non-contrast-enhanced area shown on postcontrast computed tomography (CT) or postcontrast magnetic resonance imaging (MRI) in cases of non-Hodgkin's lymphoma (NHL) may indicate that the primary tumor has a high degree of malignancy. This study was planned to determine whether this indicated a poor prognosis. Fifty-six patients with NHL (32 males and 24 females) underwent diagnostic imaging; the internal characteristics of the primary lesion were evaluated retrospectively by 2 radiologists. Postcontrast CT with 2 mL/kg of contrast medium was performed in 46 cases during the equilibrium phase, and postcontrast MRI was also performed in 10 cases by the spin echo method following an 0.1 mmol/kg intravenous injection of gadopentetate. Ten (17.8%) of the 56 cases with NHL showed an irregular non-contrast-enhanced area. The 5-year survival rate for cases with homogeneous enhancement was 77.5%, while the actuarial survival rate at 44 months for cases with an irregular non-contrast-enhanced area was 25.4% (P<0.005). From the results of multivariate analysis using Cox's regression model for 11 factors (internal characteristics, sex, age, clinical stage, primary site, size, lactic dehydrogenase value systemic symptoms, cell marker, histopathologic criteria, and therapy), symptoms (P=0.0001) and internal characteristics (P=0.0164) were selected as the variants affecting the prognosis. No correlations were found between internal characteristics and other variants. Contrast CT or MRI should be evaluated before treatment, as the presence of an irregular non-contrast-enhanced area indicates a poor prognosis.

コンピューター断層撮影 (CT) を利用した成人水腎症における腎保存手術の適応基準の検討

The cases with adult hydronephrosis are usually performed either conservative surgery or nephrectomy according to the grade of residual renal function. The residual renal function of adult hydronephrosis are usually suspected with analysis of concentration and/or clearance of the renal urine content after percutaneous nephrostomy. However, percutaneous nephrostomy is invasive and risky. On the other hand, post-contrast computed tomography (CT) is non-invasive. We studied whether post-contrast CT is available for the assessment of residual renal function of adult hydronephrosis and also studied the indication for conservative surgery of adult hydronephrosis on post-contrast CT. Conservative surgery or nephrectomy was performed in 14 patients with adult hydronephrosis in the duration from April, 1986 to March, 1995. All of 14 patients (14 kidneys) hydronephrosis were retrospectively studied of the character in the indication for conservative surgery by post-contrast CT before surgery. The indication for conservative surgery of adult hydronephrosis on post-contrast CT are (1) well enhanced renal parenchyma exist round the kidney, even if it is very thin, and (2) excretion of contrast medium to renal calyx are showed. It was concluded that post-contrast CT might be useful for the assessment of residual renal function of adult hydronephrosis.

Clinical and radiological pictures of hepatocellular carcinoma with intracranial metastasis.

Hepatocellular carcinoma (HCC) with extrahepatic spreading is not uncommon. In order to delineate the clinical and radiological pictures of HCC with intracranial metastasis, 33 documented cases were analysed. Eighteen had brain parenchymal metastasis without skull involvement; the other 15 cases disclosed skull metastasis with brain invasion. The underlying HCC are mainly of expanding (13/33, 39.4%) and multifocal (13/33, 39.4%) types. Eighteen cases (18/33, 54.5%) had mental changes not related to hypoglycaemia or hepatic encephalopathy. Eighteen cases (18/20, 90%) disclosed hyperdense mass lesions by non-contrast computed tomography (CT) scans and 17 cases showed homogeneous enhancement (17/22, 77.3%) by post-contrast CT images. In the non-skull involved group, five cases (5/12, 41.7%) disclosed ring-shape enhancement and 14 cases (14/16, 87.5%) had perifocal oedema, which were not seen in the skull involved group. Eight cases (8/33, 24.2%) presented as intracerebral haemorrhage. Twelve (12/33, 36.4%) died of brain herniation. Most (14/18, 77.8%) non-skull involved cases had simultaneous lung metastasis without bony metastasis, while the skull involved group often (10/15, 66.7%) disclosed extracranial bony metastasis without lung metastasis. The difference in extracranial metastasis was statistically significant (P < 0.05). The multivariate survival analysis disclosed that lower lactate dehydrogenase level (< or = 316 U/L, P = 0.029) and treatments (surgery or radiation, P = 0.001) were positively associated with longer survival. In conclusion, HCC with intracranial metastasis is symptomatic and life-threatening. Half the cases may come from pulmonary metastasis and the other half may be from bony metastasis. Brain irradiation or surgery can prolong their survival.

MRI of dural carotid-cavernous fistulas comparisons with postcontrast CT

Ten patients with dural carotid-cavernous fistulas (CCFs) who presented with ophthalmic manifestations were studied using postcontrast computed tomography (CT), magnetic resonance imaging (MRI), and selective cerebral arteriography. The lesions of two patients were bilateral. An enlarged cavernous sinus (CS) was diagnosed in 6 of the 12 involved sides using postcontrast CT. An abnormal flow void in the CS was detectable in 11 of the 12 using MRI. A dilated superior ophthalmic vein (SOV) was demonstrated in all of the involved sides by postcontrast CT, and in 9 of the 12 by axial MRI. Thus, both postcontrast CT and MRI are relatively useful and complementary in the diagnosis of dural CCFs. Patients should be followed with selective cerebral arteriography for definitive diagnoses and for therapeutic planning.

Acute bacterial nephritis: A clinicoradiologic correlation based on computed tomography

purpose: Acute bacterial nephritis (ABN) represents localized, nonliquefied renal infection, and the subsequent alteration of tissue densities can be readily detected by computed tomography (CT). In recent literature, a variety of renal parenchymal alterations observed on CT were reported. However, previous reports on the clinical course of ABN were inconsistent and lacked correlation with radiologic findings. In this investigation, we attempt to correlate the severity of clinical manifestations with CT findings in ABN and draw some conclusions regarding the natural history, pathophysiology, and clinical management of this disease. patients and methods: From July 1988 to June 1991, 30 cases of ABN were evaluated at our institute. On the basis of postcontrast-enhanced CT findings, 28 cases were grouped into (1) Group I (7 cases), wedge-shaped lesions (focal or diffuse); (2) Group II (12 cases), focal mass-like lesions; and (3) Group III (9 cases), diffuse (multifocal) mass-like lesions. The clinical features and outcomes of the three groups were compared. The positive detecting rates and clinical usefulness of ultrasonographic (US) and urographic examinations were also studied in each group. results: An excellent correlation can be demonstrated between the clinical parameters (including underlying diseases, maximum temperature and leukocyte count, duration of fever, flank pain, leukocytosis, and pyuria; the incidence of septic shock, diabetic ketoacidosis, and acute renal failure; and outcome) and the pattern of renal parenchymal abnormalities detected on CT. The clinical features in Group I patients displayed many similarities with those in uncomplicated acute pyelonephritis (APN) reported previously, and responded to antibiotic therapy promptly. Most patients in Group II were successfully treated with antibiotics but had a protracted clinical course with a slower clinical improvement than Group I. Only one case with a Group II lesion was noted to progress to renal abscess formation and extrarenal involvement. In comparison, 33% of the patients in Group III died despite antibiotic therapy. Our data also show that US examination is sensitive in detecting Group II ABN lesions (62% positive rate), and revealed marked renal enlargement in most Group III lesions (89%). It is therefore a useful initial imaging modality in providing information vital to clinical decision making. conclusion: Our experiences suggest that renal bacterial infection may show the continuum of severity from uncomplicated APN to ABN, demonstrated on postcontrast CT scan as wedge-shaped lesions to mass-like lesions, and possibly, finally to frank abscess formation. We classify ABN into three subgroups according to CT findings, and good correlation with clinical severity is demonstrated. These findings deliver valuable concepts regarding the pathophysiology and clinical management of this disease.

Delayed Postcontrast CT and MR Imaging of Chondroid Chordoma —Case Report—

A rare case of intracranial primary chondroid chordoma is reported with special reference to neuroradiological findings. A precontrast computed tomographic (CT) scan revealed an isodense mass with multiple flecks in the right cerebellopontine region. A postcontrast CT scan showed slight ring enhancement. A delayed postcontrast CT scan demonstrated marked homogeneous enhancement extending from the middle cranial fossa to the cerebellopontine region on the right. Magnetic resonance (MR) imaging demonstrated a well-defined lesion as a high-intensity mass on T2-weighted image and a low-intensity mass on T1-weighted image. A MR image 5 minutes after gadolinium-diethylenetriaminepenta-acetic acid administration showed heterogeneous enhancement. A MR image 30 minutes after the contrast administration showed more marked, homogeneous enhancement. Such delayed postcontrast CT and MR imaging are useful in the differentiation of chondroid chordoma from classical chordoma.

Microcystic adenoma of the pancreas: Report on four cases and review of the literature

Four cases of microcystic adenoma of the pancreas, including ultrasonographic (US) and computed tomographic (CT) data, are described. These tumors generally present as large, well-delimited pancreatic masses whose multicystic nature is readily evidenced on postcontrast CT scans. While the presence of cysts less than 2 cm in diameter and a central, star-like calcification are very specific, the frequency of atypical forms generally justifies exploratory surgery.

Computed tomography attenuation measurements for the characterization of hepatic haemangiomas

The attenuation values of 21 hepatic haemangiomas in 19 patients were measured on non-enhanced computed tomographic (CT) scans and compared with the attenuation of adjacent liver and the inferior vena cava (IVC). The attenuation of hepatic haemangiomas was lower than that of the surrounding liver, but there was no correlation between these two measurements. There was a highly significant correlation between the attenuation of haemangiomas and blood in the vena cava (r = 0.905, p less than 0.001). All the haemangiomas had attenuations within 7 HU of caval blood. By comparison, in 34 hypodense hepatic lesions that did not show contrast-enhanced appearances characteristic of haemangioma, there was no significant correlation between the attenuation of the lesions and the IVC. Nineteen (56%) of these lesions had attenuations differing more than 7 HU from that of caval blood. The influence of this observation on the requirement for dynamic contrast-medium-enhanced and delayed post-contrast CT in the assessment of hepatic lesions is discussed.

Bone Scintigraphy in Acute Renal Failure with Severe Loin Pain and Patchy Renal Vasoconstriction

To evaluate the patterns of renal images and the diagnostic value as a screening test of the whole-body bone and renal scintigraphy with technetium-99m-methylene diphosphonate (99mTc-MDP) or -pyrophosphate (99mTc-PYP), we performed bone scintigraphy in 6 patients with acute renal failure (ARF) with severe loin pain and patchy renal vasoconstriction on postcontrast renal computed tomography (CT). All 6 patients were young and previously healthy but experienced severe loin pain after track events. Five took analgesics. Postcontrast renal CT showed patchy low-density areas or diffuse enhancement immediately after radiocontrast injection and then patchy wedge-shaped enhancement 24 or 48 h later, which subsequently disappeared 72 h later. On the whole-body bone scintigrams with 99mTc-MDP or 99mTc-PYP before obtaining renal CT, there was no increased uptake of isotope in the soft tissue, and multiple patchy increased accumulations of the isotope in the kidney were observed in 5 patients. In 2 patients, renal scintigraphies with technetium-99m-dimercaptosuccinate showed photon-deficient areas in the same areas of patchy isotope accumulation in the whole-body bone scintigraphies. Whole-body image and renal scintigraphy with bone-seeking agents may be useful as a screening test and in the search for the theoretical evidence of ARF with severe loin pain and patchy renal vasoconstriction.

Choroid Plexus Metastasis of Lung Carcinoma

Metastatic tumors in the choroid plexus are generally considered to be very rare. The authors present a case of lung large cell carcinoma with a single metastatic tumor in the choroid plexus of the lateral ventricle trigone. Precontrast computed tomographic (CT) scans showed an isodensity mass with extensive peritumoral edema, which was considerably enhanced on the postcontrast CT scans. Magnetic resonance (MR) images demonstrated the mass as a low-intensity area on the T1-weighted image and an iso-intensity area on the T2-weighted image. The tumor was clearly differentiated from the peritumoral edema by both CT and MR imaging. The diagnosis was confirmed by surgery.

Arteriovenous Malformation in the Cerebellopontine Angle Presenting as Hemifacial Spasm

A 64-year-old female was admitted with a 6-year history of right hemifacial spasm. Neurological examination and precontrast computed tomographic (CT) scanning showed no abnormality. Vertebral angiography disclosed, however, a small arteriovenous malformation (AVM) in the right cerebellopontine angle. A postcontrast CT scan demonstrated a high-density area in the right cerebellomedullary junction which appeared as a flow-void signal on magnetic resonance images. A right retromastoid craniectomy was performed to separate an enlarged and tortuous loop of the right anterior inferior cerebellar artery from the right facial nerve using a Teflon-felt sheet. The AVM was not excised. Postoperatively, she was completely free of hemifacial spasm.

"Pseudo-Delta Sign" on Computed Tomography in an Extremely Acute Stage of Superior Sagittal Sinus Thrombosis—A Case Report

A case of superior sagittal sinus (SSS) thrombosis with a "pseudo-delta sign" on computed tomography (CT) is reported. The so-called "empty delta sign," which usually appears following contrast enhancement, is reliable in the CT diagnosis of SSS thrombosis but may not appear, it is said, in the extremely acute stage. In this patient, however, the "empty delta sign" appeared with precontrast CT scans and disappeared with postcontrast CT scans, "pseudo-delta sign," in the extremely acute stage of SSS thrombosis. On the precontrast CT, blood surrounding the sagittal sinus outlined it; when contrast was given, it became dense with blood.

Multicentric Intracranial Fibrous Xanthoma

Intracranial fibrous xanthoma is extremely rare; only 11 cases have been reported so far. The authors report a case of multicentric intracranial fibrous xanthoma. Precontrast computed tomographic (CT) scans revealed a left frontal subdural mass, which had previously been diagnosed as a chronic subdural hematoma at another hospital. However, operation disclosed no hematoma but a granulomatous tumor. The biopsied specimen was histologically diagnosed as fibrous xanthoma. Postoperative postcontrast CT scans showed intense homogeneous enhancement at the clival and the left frontal regions, both of which appeared as iso- to low-intensity areas on T1-weighted magnetic resonance (MR) images and as low-intensity areas on T2-weighted MR images. She gradually recovered by conservative treatment but suddenly died of cerebral infarction. Autopsy revealed fibrous xanthomas in the left frontal and the clival regions. This is the first report of the use of MR imaging for intracranial fibrous xanthoma, and its features differ from those of common intracranial parenchymal tumors, MR imaging can be helpful in the diagnosis of this tumor.

Lumbar disc disease evaluated by myelography and postmyelography spinal computed tomography.

Five- and ten-millimeter-thick transverse axial computed tomography (CT) scans were obtained at lumbar disc spaces in 81 patients with suspected lumbar disc disease. Scans were obtained following metrizamide myelography. CT and myelography findings were compared and correlated with clinical and surgical findings. Postmyelography CT scan was superior to myelography in 68% since it was able to demonstrate even small herniations. It was especially valuable in the L5-S1 space where the wide epidural space can hide the disc herniation without it being demonstrated by myelography. Also other kinds of pathology which may simulate or complicate disc herniation were readily evaluated by postmyelography CT. Although noncontrast CT scans are usually diagnostic and sufficient, the improved anatomical details obtained by postcontrast CT scans, increase the diagnostic accuracy, and selected, complicated cases may need the CT study with intrathecal metrizamide.

Use of meglumine iotroxate in the detection of liver tumors by computed tomography

Experience with contrast enhanced computed tomographic (CT) examinations of 13 patients with hepatic tumors using a new cholangiographic contrast material, meglumine iotroxate, is described. After infusion, small density differences between the tumor and liver were accentuated. In 11 cases postcontrast CT using meglumine iotroxate improved visualization of lesions compared with conventional pre-and postcontrast CT using urographic contrast material. Our results indicate that contrast enhanced CT using meglumine iotroxate is a promising alternative to conventional CT in the detection of hepatic tumors.

CT patterns of splenic infarction: a clinical and experimental study.

The computed tomographic (CT) appearance of splenic infarction has classically been described as peripheral, wedge-shaped, and low in density. Two investigations were designed to determine the appearance of splenic infarcts: (a) a clinical study of 12 patients and (b) a canine experimental model. In the clinical study, two previously undescribed patterns of splenic infarction were found. The classic peripheral, wedge-shaped defects were seen in four patients; multiple, heterogeneous lesions were seen in five; and massive hypodense lesions were noted in three. In three of the nine patients who had both precontrast and postcontrast CT scans, the unenhanced images alone would not have permitted the diagnosis. Contrast enhancement markedly improved infarct visualization in the remaining six. The experimental study of splenic infarction in dogs indicated that CT images can accurately depict the various phases of an infarct as it evolves through stages of congestion, hemorrhage, inflammation, organization, and fibrosis. In addition, a new contrast material--liposome-encapsulated diatrizoate--was used in one of the dogs and was found to produce greater and more sustained differences between normal and abnormal tissue than did conventional contrast material.

骨髄炎に対するＣＴ診断の応用

Computed tomography (CT) was performed in conjunction with conventional rediography and angiography in four patients with subacute or chronic osteomyelitis. CT can exclude or establish medullary involvement, differentiate overlying soft-tissue from underlying bony abnormality, and clearly delineated anatomy of soft tissues. Bone window setting is valuable in demonstrating bony abnormality, and post-contrast CT is able to demonstrate soft tissue abnomality. CT can distinguish between malignant bone tumor and osteomyelitis.

Staging of human brain abscess by computed tomography.

Precontrast and postcontrast computed tomographic (CT) scans of patients with brain abscesses were quantitatively studied to determine if the degree of encapsulation could be predicted. The findings in these cases correlated closely to the CT criteria for encapsulation previously established in an experimental model. Time-density curves of serial delayed postcontrast CT scans and the precontrast CT appearance yielded accurate criteria for determining the degree of encapsulation. The effect of corticosteroid treatment on contrast enhancement of brain abscess was also studied in one patient.

Computed tomography in moyamoya disease.

Eighteen patients with moyamoya disease were examined by computed tomography (CT). At the first examination, CT findings were normal in one patient and abnormal in 17 patients. Significant abnormalities on precontrast CT were characterized by low density lesions in 14, ventricular dilatation in 9, and cerebral atrophy in 11 patients. Postcontrast CT showed the presence of contrast enhanced lesions in three patients. Follow-up examinations were performed in 13 patients, and the following changes on CT were found in 10 of them: increase or development of low density lesions in 10, ventricular dilatation in 4, cerebral atrophy in 5, appearance of a contrast enhanced lesion in 1, and disappearance of the enhanced lesion in 3. The patient with normal findings at the first examination showed a low density lesion on the second examination. The abnormal vascular networks in the region of the basal ganglia were visualized successfully in six examinations of five patients by higher concentration of contrast medium in blood than usual. Abnormal CT findings consisted of those seen in multiple cerebral infarctions and the visualization of the abnormal vascular networks. Computed tomographic findings on these patients showed evolution as seen in clinical and angiographic findings.