Low rate of contrast-induced Nephropathy after CT perfusion and CT angiography in acute stroke patients

Background

The aim of the study was to assess (i) the rate of contrast-induced nephropathy (CIN), (ii) the amount and time course of renal dysfunction, (iii) the identification of risk factors and calculation of a risk score for CIN in acute stroke patients after CT perfusion (CTP) and CT angiography (CTA).

Methods

162 patients were investigated,who had received 140 ml of non-ionic low osmolar contrast agent (300 mg iodine per ml, Ultravist 300^®, Schering AG) for CTA and CTP. We assessed electrolytes, creatinine, and creatinine clearance before and up to 7 days after administration of contrast agent. In addition, the risk factors for CIN were recorded and a previously validated risk score for CIN was calculated.We also assessed the amount of crystalloid fluid substitution and newly prescribed drugs. CIN was defined as an increase of the serum creatinine-level of > 0.5 mg/dl or > 25% above baseline within 48 hours after contrast agent administration.

Results

154 patients (94 %) received crystalloid fluid substitution (mean 6.1 l) within 48 h after contrast agent administration. During follow-up the creatinine values and the creatinine clearance remained stable while sodium and potassium increased significantly (p < 0.0001) after contrast agent administration. In patients with a pathological creatinine value on admission (n = 40), the creatinine clearance did not decrease significantly (p = 0.18). The risk score for developing a CIN was low in the majority of stroke patients. A manifest CIN occurred in 3 patients (2 %). No patient had to be hemodialysed.

Conclusion

CIN is a rare complication in acute stroke patients examined by multimodal contrast-based CT due to the low prevalence of risk factors associated with CIN. In conjunction with appropriate fluid substitution, low osmolar nonionic contrast agents seem to be safe in clinical routine.

     

Absence of contrast enhancement on CT brain scans of patients with supratentorial malignant gliomas

The medical records of 229 consecutive patients with supratentorial malignant gliomas were reviewed with respect to histology, age at diagnosis, tumor location, and enhancement pattern on the CT obtained after the administration of contrast material at the time of operation. Nonenhancing tumors were identified in four (4%) of 93 patients with glioblastoma multiforme (GM), three (30%) of ten with gemistocytic astrocytoma (GA), 23 (31%) of 74 with highly anaplastic astrocytoma (HAA), and 28 (54%) of 52 with moderately anaplastic astrocytoma (MoAA). The age-related incidence of the various glioma histiotypes (both enhancing and nonenhancing) was reflected by the median age at diagnosis: 50 years in GM, 52 years in GA, 40 years in HAA, and 34 years in MoAA. The age and CT contrast enhancement pattern were similar in patients with GM, GA, and MoAA; patients with nonenhancing HAAs tended to be younger at presentation. The tumor location and the frequency of enhancing and nonenhancing lesions were similar for all groups except MoAA, in which nonenhancing tumors were most often frontotemporal and enhancing tumors were usually frontoparietal. Our results demonstrate that it is important to obtain histologic confirmation of the diagnosis in patients with supratentorial gliomas regardless of the presence or absence of contrast enhancement of the tumor on CT, because neither of these characteristics correlates with the tumor histology.     

Primary intracerebral hemorrhage: impact of CT on incidence

From 1975-1979, the incidence of primary intracerebral hemorrhage (PIH) increased in Rochester, MN, when compared with a previously decreasing incidence. Judging from patients with PIH who were alert at diagnosis, we estimated that 24% of the hemorrhages in earlier years had been mislabeled as infarction. The 30-day survival rate increased from 8% in 1945-1974 to 44% in 1975-1979. The incidence rate was about 45% higher in patients receiving anticoagulant treatment than in those who did not. The increased incidence rate and improved survivorship were attributed to more frequent identification of small PIH by CT.     

Use of CT in epilepsy: does it matter how long you wait?

Computer tomography (CT) of the brain is of value for finding potentially correctable lesions in adult patients with new onset seizures. The value of CT is unknown, however, for finding such lesions in adult chronic epileptic patients without prior CT. We compared a group of 177 adult patients who had CT within a year from the onset of seizures to a group of 93 patients who had a history of seizures for more than a year before CT was performed. In the first group, 33 potentially correctable lesions (19%) were found including 17 tumors. The group with chronic epilepsy had 4 (4%) potentially correctable lesions: 3 arteriovenous malformations and 1 meningioma. It seems that CT is of value in discovering potentially removable lesions in chronic epileptic patients, but the likelihood is relatively small. The incidence of stable structural lesions seems to be similar in the two groups.     

Neuro-Beh?et's disease: CT and clinical correlates

We examined the serial CTs and clinical courses of five patients with neuro-Beh?et's disease and reviewed ten previously reported cases, all with focal CT abnormalities. The CT lesions were in the brainstem (8 patients), basal ganglia (7), thalamus (4), or hemispheric white matter (7). Of the 13 patients who received contrast, nine had lesions that showed enhancement. In five, lesions were visualized with contrast that were not apparent without it. The CT lesions were usually accompanied by corresponding clinical deficits, although in some patients deficits were more extensive than the CT predicted. In nine patients, contrast enhancement decreased or disappeared over days to weeks, often with associated clinical improvement. In eight patients followed serially, CT abnormalities resolved completely or substantially. Based on these cases, we conclude that (1) CT abnormalities of gray and white matter occur commonly in neuro-Beh?et's disease with focal deficits, and help support the diagnosis; (2) CT abnormalities, particularly contrast enhancement, correlate well with the activity of parenchymal disease; and (3) the concomitant improvement of clinical and CT abnormalities with resolution of contrast enhancement suggests that partially reversible inflammatory changes associated with breakdown of the blood-brain barrier may produce some of the neurologic and radiographic deficits in this illness.     

CT enhancement after prolonged high-dose contrast infusion in the early stage of cerebral infarction

To demonstrate the BBB break-down on the CT image in the acute stage of cerebral infarction, a 3 hour continuous drip infusion of 200 ml of meglumine amidotrizoate, rather than the conventional bolus injection, was used. In this study, 22 examinations were carried out in 18 patients in whom cerebral infarction due to temporary or permanent obstruction of the cerebral artery was diagnosed by CT and angiography on admission. With each examination, the first CT was obtained prior to contrast infusion, and second immediately after the end of 3 hours of continuous contrast infusion. The EMI number was calculated at 3 regions of interest in the infarction. Within 3 days after stroke episode, 4 out of 5 patients with temporary vascular obstruction demonstrated enhancement, as well as 6 out of 9 patients with permanent vascular obstruction. Between 4 and 14 days after the stroke episode, all of 8 patients showed enhancement. To further clarify the extravasation of the contrast medium during the first 3 days of a cerebral infarction, a third CT scan was performed 3-hrs after finishing the contrast infusion in 4 patients. In these latter patients, blood was sampled at the time of each of the 3 CT series. The EMI number of the blood samples was also measured. In all 4 patients, the Gado's tissue-blood ratio (the EMI number of the CT lesion divided by that of the blood sample) was higher than 17.2% in the second, and higher than 54.7% in the third CT scan. Thus break-down of the BBB which was demonstrated by prolonged contrast infusion is an earlier event in human cerebral infarction than is usually accepted.     

Comparative studies of brain CT scan in schizophrenia]

CT Scan was undertook to 48 schizophrenics and 30 healthy volunteers. The results revealed that: the incidence rate of CT abnormalities was higher in schizophrenics than in normal control; the incidence rate of CT abnormalities in winter-born schizophrenics was higher than in non-winter-born patients; the incidence rate of abnormalities was higher in familial type schizophrenics than in sporadic type; the incidence rate in negative symptom schizophrenics was higher than in positive symptom patients.     

Early post-operative seizures after burr-hole drainage for chronic subdural hematoma: correlation with brain CT findings.

The incidence of seizures in patients undergoing burr-hole crainiostomy with closed-system drainage for chronic subdural hematoma (CSDH) is low. The post-operative use of anticonvulsants is, thus, controversial. In this study, we tried to correlate pre-operative computed tomographic (CT) appearance of the CSDH with the need for post-operative seizure prophylaxis. From April 1998 to November 2001, 128 cases of CSDH surgically treated at our hospital were studied. All patients underwent burr-hole craniostomy with closed system drainage. All CSDHs were classified as low-density, isodense, and mixed-density lesions according to CT findings. The incidence of early post-operative seizures (within 3 weeks of surgery) among all patients was 5.4% (7/128). In the subgroups by lesion density, the incidences were 6.2% (1/16) in the low-density group, 2.4% (2/83) in the isodense group, and 13.7% (4/29) in the mixed-density group (all p < 0.05). The mean age among the seven patients (five males and two females) who had seizures was 71 years. The locations of the CSDHs among the 128 patients were the left side of the brain in 53 (41.4%) patients, right side in 45 (35.2%), and bilateral in 30 (23.4%) patients. Among the seven patients who suffered from post-operative seizures, five (71.4%) had left side CSDHs, one (14.2%) had a right side CSDH, and one (14.2%) had bilateral CSDHs. We concluded that the post-operative seizure rate appeared high in the group with mixed-density type lesions on CT, and in those with left unilateral CSDH. We suggest the use of prophylactic anticonvulsants for patients with mixed-density lesions on pre-operative CT.     

Vanishing CT lesions in epilepsy.

Experience with computed tomography (CT) in patients with epilepsy has drawn attention to specific type of cerebral lesions widely prevalent in this part of the world. The lesions disappear spontaneously while patients receive only anticonvulsant therapy. The exact nature of these lesions is not yet understood. One-hundred and twenty-two such patients (M 77; F 45) were studied. Their age ranged from 3 to 57 (mean 21.8 +/- 12.7) years. Seizures were partial motor in 86 (70.5%), generalised tonic clonic in 31 (25.4%), complex partial in 4 and atonic in one case. Postictal hemiparesis was seen in 6 patients who completely recovered within 5 min to 7 days. One hundred patients underwent EEG examination. It was abnormal in 84 cases; 40 patients showed localisation which correlated with CT findings. Plain CT showed low attenuation lesions in all cases. Morphology on contrast enhancement was ring lesion in 50 (40.9%), disc lesion in 47 (38.5%), target lesion in 3 (2.5%), mixed lesion in 2 (0.8%), no enhancement in 18 (14.8%) and a speck with oedema in 2 (0.8%) cases. All lesions were cerebral, present at cortical-subcortical junction. The first follow-up scan was performed in 78 (63.9%) patients within 6-12 weeks. It showed complete disappearance of the lesion in 47 (60.3%) cases. Reduction in size of the lesion and surrounding oedema was observed in 24 (30.8%) cases. The follow-up scans in these 24 cases revealed disappearance of lesion in 11 cases and almost complete resolution of the lesion with a remaining speck in 13 cases. Cerebrospinal fluid (CSF) was normal in 95 out of 100 cases in which it was performed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical course and CT findings in patients with contrast media-associated seizures

It is well known that convulsion is one of serious adverse reactions of x-ray contrast media. The occurrence of the convulsion seems to be very rare in general population. However, a few reports noticed recently that patients with brain metastases or gliomas developed this complication relatively frequently and the terms, as contrast-induced convulsion or contrast media-associated (induced) seizure, were used. We performed 12,479 cranial CT examinations with contrast enhancement during the last nine years. The amount of 100 ml in adult or 2 ml/kg in children of 65% Angiografin (methylglucamine diatrizoate) was given intravenously and five patients had contrast media-associated seizures. Case 1: A 37-year-old man with right frontal anaplastic glioma was treated surgically and with radiochemotherapy and hyperthermia. In spite of anticonvulsant therapy, general or left hemiconvulsions occurred sometimes. The patient had contrast-induced general convulsion at 16th CT examination which revealed enhancement in the wall of surgical tissue defect. At 26th CT study, he developed general convulsion again. Case 2: A 47-year-old man with anterior callosal anaplastic glioma was treated surgically and with radiochemotherapy and hyperthermia. After then, he had contrast media-associated general convulsion at 10th CT examination which showed enhanced lesions. Case 3: A 63-year-old woman had been treated surgically for lung cancer. Five years later, CT revealed a ring enhancement in the left frontal lobe. Radiation reduced the lesion gradually.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of various CT imaging methods for diagnosis of acute ischemic cerebrovascular disease

Thirty-four patients with cerebral infarction and 18 patients with transient ischemic attack were examined by multi-slice spiral CT scan, CT perfusion imaging, and CT angiography within 6 hours after onset. By CT perfusion imaging, 29 cases in the cerebral infarction group and 10 cases in the transient ischemic attack group presented with abnormal blood flow perfusion, which corresponded to the clinical symptoms. By CT angiography, various degrees of vascular stenosis could be detected in 41 patients, including 33 in the cerebral infarction group and eight in the transient ischemic attack group. The incidence of intracranial artery stenosis was higher than that of extracranial artery stenosis. The intracranial artery stenosis was located predominantly in the middle cerebral artery and carotid artery siphon, while the extracranial artery stenosis occurred mainly in the bifurcation of the common carotid artery and the opening of the vertebral artery. There were 34 cases (83%) with convict vascular stenosis and perfusion abnormalities, and five cases (45%) with perfusion abnormalities but without convict vascular stenosis. The incidence of cerebral infarction in patients with National Institutes of Health Stroke Scale scores ≥ 5 points during onset was significantly higher than that in patients with National Institutes of Health Stroke Scale scores < 5 points. These experimental findings indicate that the combined application of various CT imaging methods allows early diagnosis of acute ischemic cerebrovascular disease, which can comprehensively analyze the pathogenesis and severity of acute ischemic cerebrovascular disease at the morphological and functional levels.     

CT in simple partial seizures in children: a clinical and computed tomography study

Introduction – Therapeutic relevance of computed tomography (CT) in children with simple partial seizures (SPS) is reported to be remarkably low (1–2%). There are no studies, however, from the developing countries where neuroinfections are among important causes of seizures. The present study from India is aimed at evaluating the significance of CT in the management of SPS in children and to determine the difference in clinical features of children with and without focal brain lesions in CT. Patients and methods – CT scans of all patients aged 15 years or younger with SPS, seen over a period of 15 months, were reviewed. The clinical features of the patients with focal lesions in the CT were compared with those of children without focal abnormalities. Results – Focal structural lesions were present in 117 (59.09%) of 198 children. These included: solitary contrast enhancing CT lesion – 16.16%, focal calcification – 12.12%, cysticercosis – 10.10%, focal atrophy – 9.59%, tuberculoma – 6.56% and infarction – 6.06%. Neuroinfections or their sequelae were responsible for seizures in 89 children (44.94%). There were no statistically significant differences in clinical features of patients with and without focal lesions in CT. Conclusion – CT study in children with SPS in developing countries has significant therapeutic relevance. It is not possible to clinically differentiate children with focal lesions from those without focal lesions in CT.     

CT findings in acute MS

In 5 patients with definite or highly probable MS, unusually large hypodense plaques are seen by computerized tomography (CT scan). The active plaques all show enhancement after i.v. contrast medium injection, suggestive of blood-brain-barrier-damage, and differ from the well-known CT findings in chronic MS patients, causing diagnostic difficulties between glioma and infarction.     

Indications for brain CT scan in patients with minor head injury

OBJECTIVES: Minor head injury is the most common type of head injury. Despite of high incidence and numerous studies performed, there is much controversy about correct evaluation of these patients. The aim of this study was to find clinical signs and symptoms which help to predict the indications for brain CT scan following minor head injury. METHODS: A series of 682 consecutive patients who had been attended at two university hospitals (Alzahra and Kashani) with minor head injury (GCS=15) were prospectively enrolled in this cohort study. In all cases clinical signs and symptoms were collected and a cranial computerized tomography (CT) scan was obtained. The relationship between the occurrence of clinical findings and appearance of intracranial posttraumatic lesions on cranial CT was analyzed by chi-square tests and statistic logistic regression methods, with 95% confidence intervals. RESULTS: Of 682 patients, 46 (6.7%) presented brain injuries on CT scan. All patients with abnormal CT scans had at least one of the following factors (risk factors): posttraumatic amnesia, loss of consciousness, posttraumatic seizure, headache, vomiting, focal neurological deficit, skull fracture, coagulopathy or antecedent of treatment with anticoagulants and patient age older than 60 years. No abnormal CT scans were found among patients without any of those risk factors on admission. Vomiting, skull fracture and age greater than 60 years were risk factors significantly correlated to an abnormal cranial CT after head injury. The presence of several risk factors in a patient increased the probability of posttraumatic lesion on CT scan. CONCLUSION: Some clinical risk factors can be used as a guide to predict the probability of abnormal CT following minor head injury.     

CT perfusion cerebral blood flow imaging in neurological critical care

Computed tomography (CT) perfusion imaging is a technique for the measurement of cerebral blood flow, cerebral blood volume, and time-to-peak or mean transit time. The technique involves the administration of a single-bolus dose of iodinated contrast material, followed by spiral CT imaging during the passage of the contrast bolus through the cerebral vasculature. CT perfusion is a fast and inexpensive brain imaging modality for use in the management of patients with various neurological disorders, ranging from acute stroke to subarachnoid hemorrhage. This article reviews the technique of CT perfusion and presents several illustrative cases in which this imaging modality was used effectively in the critical care of patients with neurological disorders.     

The role of computed cranial tomography (CT) in epilepsy

To evaluate the usefulness of CT in detecting unexpected brain lesions in epileptics, scan results were analyzed in a consecutive series of 196 adult epileptics in whom there was no known etiology for their seizures nor any abnormality on neurological examination. Nineteen additional epileptics, selected on the basis of an unexpected positive CT were also included for analysis. In the consecutive series, the overall incidence of abnormal scans was 16% with the highest yield (44%) found in patients with partial elementary seizures. Partial seizures secondarily generalized were correlated with a significantly higher CT positivity than purely partial seizures. Patients with seizures for less than six months more frequently showed CT abnormalities than patients with a longer history. In 25 of 51 cases with abnormal scans a specific lesion amenable to therapy was detected, including 16 neoplasms and 5 arteriovenous malformations. Other lesions included generalized or focal atrophy, infarcts, calcified lesions of tuberous sclerosis, unexplained calcifications and focal low-density or enhancing lesions.     

多层CT评价颈动脉重度狭窄性病变的初步研究

目的探讨多层CT脑灌注技术和头颈部CT灌注成像(CTA)技术联合应用评价颈动脉重度狭窄性病变的临床价值。方法对23例有症状的颈动脉重度狭窄性病变进行颅脑平扫、脑CT灌注和头颈部CTA联合检查。利用CTA对血管的狭窄程度、狭窄部位进行评价,利用CT灌注对脑血流动力学状态进行评价。选10名年龄相匹配的志愿者行CT灌注检查,作为CT灌注的对照组。结果CTA显示一侧颈内动脉闭塞12例,一侧颈内动脉重度狭窄11例。7例为单侧颈内动脉病变,16例为多血管多部位狭窄,包括对侧颈动脉狭窄,单侧或双侧椎动脉狭窄或闭塞,颅内血管狭窄或闭塞。脑CT灌注显示病变同侧灌注异常17例,闭塞组(8例)和重度狭窄组(9例)在灌注异常的发生率上差异无统计学意义。单发组(3例)和多发组(14例)在灌注异常发生率上差异有统计学意义(P<0·05)。结论颈动脉重度狭窄性病变多伴有同侧脑灌注的异常(17/23),多血管病变脑内灌注异常的发生率多于单发的颈动脉狭窄或闭塞。CTA和CT灌注技术联合应用可更加全面地评价颈动脉狭窄性病变,具有较高的临床应用价值。     

Enhancing mass on CT: neoplasm or recent infarction?

On CT, mass effect and contrast enhancement have limited value in separating brain neoplasm from infarct, because both findings are frequent with recent infarction. Review of CT in 100 patients with histologically proven supratentorial lesions (35 infarcts and 65 tumors) indicated the specificity of three helpful signs: (1) White matter edema outlined the uninvolved cortex in 73% of metastases and in 74% of gliomas but only in 14% of infarcts. (2) The cortical ribbon was enhanced in 43% of infarcts, in 7% of gliomas, and in 4% of metastases. (3) Selective sparing of the thalamus occurred in 31% of infarcts but only in 7% of tumors.     

CT brain findings in clinical dementia investigation--underestimation of mixed dementia

Dementia has been found to display a more heterogeneous clinical picture than previously recognized. We investigated brain changes on computed tomography (CT) in a clinical dementia population consisting of 67 cases with Alzheimer's disease (AD), 13 with mixed dementia (AD and vascular dementia, VaD), 71 with VaD, and 12 cases that were not demented. Temporal cortical atrophy and atrophy around the temporal horns were more common in patients with mixed dementia compared to patients with VaD and the non-demented, respectively. Frontal white matter changes were present in 64% of AD, in 85% of mixed dementia and in 79% of VaD cases, but there were no differences between the dementia groups. Lacunes were present in almost 40% of AD cases and in 80 and 85% of VaD and mixed dementia cases, respectively. Only 14% of the VaD cases had large infarcts on the CT. We conclude that large infarcts were rare, even in VaD cases. The increased incidence of white matter changes and lacunes in AD patients strongly indicates an underestimation of the mixed dementia diagnosis. More distinct criteria for this diagnostic category are warranted.     

Postictal deficit mimicking stroke: role of perfusion CT

OBJECTIVES: To demonstrate the use of perfusion CT in patients presenting with a suspected diagnosis of stroke to avoid the administration of inappropriate thrombolytic therapy in stroke-mimicking conditions such as status epilepticus. MATERIAL AND METHODS: We reviewed the imaging studies of four patients presenting with symptoms suggestive of stroke, but finally diagnosed with status epilepticus. Imaging was by a 16-section multidetector CT scanner using a protocol consisting of non-contrast CT, CT angiography and perfusion CT. Color-coded maps allowed calculation of the CBV (cerebral blood volume), CBF (cerebral blood flow) and MTT (mean transit time). RESULTS: In all four cases, perfusion CT revealed increases in CBF and CBV as well as a decreased MTT, consistent with hyperperfusion linked to status epilepticus with focal deficit-in contrast to the hypoperfusion observed in stroke patients. CONCLUSION: The use of perfusion CT accurately detected hyperperfusion in status epilepticus presenting as stroke. In such cases, perfusion CT imaging avoided the administration of potentially harmful thrombolytic therapy to patients experiencing seizures due to different underlying etiologies.