Subarachnoid contrast enhancement after spinal angiography mimicking diffuse subarachnoid hemorrhage

Cerebral Contrast Staining on Dual-Energy Computed Tomography After Coil Embolization of Unruptured Intracranial Aneurysms: Frequency, Risk Factors, and Clinical Implications

OBJECTIVE

Cerebral contrast staining (CCS) postendovascular procedures may mimic subarachnoid hemorrhage. This study investigates CCS frequency and risk factors using dual-energy computed tomography (DECT) following coil embolization of unruptured intracranial aneurysms.

METHODS

A retrospective analysis included 232 patients undergoing coil embolization and immediate DECT imaging between October 2018 and March 2023. CCS was defined as hyperattenuation on iodine overlay images absent on virtual noncontrast images. Logistic regression identified predictors of CCS.

RESULTS

CCS occurred in 95 patients (40.9%), predominantly in anterior circulation aneurysms (48.1%) compared to posterior circulation (14.3%, P = 0.001). High CCS rates occurred particularly in posterior communicating (59.1%) and anterior communicating/anterior cerebral artery aneurysms (59.0%). Low-osmolar contrast media had higher CCS incidence (56.4%) compared to iso-osmolar media (30.4%, P < 0.001). CCS-positive patients had higher contrast volume (186.35 ± 46.62 mL vs. 171.62 ± 34.89 mL; P = 0.009) and longer procedures (158.41 ± 41.25 vs. 135.28 ± 35.07 min, P < 0.001). Multivariate analysis identified posterior communicating artery aneurysms, low-osmolar contrast media, procedure duration, and contrast volume as independent CCS predictors. Demographic factors and blood pressure variability were unrelated. One transient contrast-induced encephalopathy case occurred; no hemorrhages were identified.

CONCLUSIONS

CCS is common after coil embolization, especially with longer procedures, anterior aneurysms, and low-osmolar contrast media. DECT effectively differentiates CCS from hemorrhage, potentially reducing unnecessary follow-up imaging.

Reversible intracranial contrast medium accumulation after embolization of unruptured cerebral aneurysms and its association with transient neurological deficits: A single center experience

BACKGROUND

Use of iodine-containing contrast medium (CM) is obligatory for endovascular treatment (EVT) of cerebral aneurysms. After EVT, intracranial density increases (DIs) can be detected in cranial computed tomography (CT). Those DI can correspond to subarachnoid hemorrhage (SAH), infarction or reversible CM accumulation (RCMA). The latter can be mistaken for hemorrhage, especially if they are accompanied by neurological deficits.

OBJECTIVE

To analyze postinterventional DI after EVT of unruptured cerebral aneurysms and associated clinical symptoms and to identify risk factors for the occurrence of RCMA.

METHODS

For differentiation of DI, we compared CT scans following EVT and additionally 24 h ± 5 h later. Diagnosis of RCMA was based on marked regression of DI on follow-up scans. We analyzed continuous variables (age, duration of intervention and anesthesia, aneurysm diameter, amount of CM and renal function) and categorial variables (gender, aneurysm location, devices for EVT, antiplatelet therapy [APT] and associated neurological deficits) to identify risk factors for the occurrence of RCMA.

RESULTS

We studied 58 patients (44 female, mean age 59.5 [range 39-81]) who underwent EVT for a total of 68 cerebral aneurysms in 62 therapy sessions over a 3-year period without periprocedural complications. Postinterventional DI occurred after 17 therapy sessions. All 17 DI turned out to be RCMA in the follow-up imaging. Two patients who had no DI on initial postinterventional CT showed new SAH on follow-up CT. Infarctions were not observed. Transient neurological deficits occurred in eight patients (12.9%) and were associated with RCMA (P = 0.010). Postinterventional RCMA was associated with the duration of EVT (P = 0.038) and with APT (acetylsalicylic acid [ASA] + clopidogrel: P =0.040; ASA alone: P =0.011).

CONCLUSIONS

RCMA is common after EVT of unruptured cerebral aneurysms and often accompanied by transient neurological deficits. Long procedure duration and APT appear to predispose to the occurrence of RCMA.

Fully Reversible Contrast-Induced Encephalopathy Mimicking Stroke after Flow Diverter Treatment of Carotid Cave Aneurysm

Contrast-induced encephalopathy (CIE) is a rare complication of coronary and neurointerventional procedures. The condition is believed to arise from endothelial damage secondary to exposure to iodinated contrast media. A wide spectrum of clinical manifestations has been reported including seizures, cortical blindness, and focal neurological deficits. This report details the case of fully reversible CIE mimicking severe anterior circulation stroke in a 55-year-old female following elective endovascular treatment with a flow diverter of a carotid cave aneurysm. The patient was managed conservatively with intravenous hydration and steroids and showed an excellent prognosis with supportive management.

Pseudosubarachnoid hemorrhage: A systematic review of causes, diagnostic modalities, and outcomes in patients who present with pseudosubarachnoid hemorrhage

Background:

Patients with computed tomography (CT) findings consistent with subarachnoid hemorrhage without evidence of hemorrhage following autopsy or cerebrospinal fluid testing are termed to have pseudosubarachnoid hemorrhage (pSAH).

Methods:

A systematic review of literature was conducted based on the preferred reporting items for systematic reviews and meta-analysis statement. Studies were evaluated for associated cause of pSAH, imaging modality used in assessment, method of confirmatory testing, and clinical outcome.

Results:

Fifty studies were included in qualitative analysis including 197 cases of pSAH. Systematic review revealed 23 studies including 110 patients with pSAH attributed to hypoxic-ischemic brain injury following cardiac arrest. Three studies were included in meta-analysis that quantitatively analyzed differences in CT densities in patients with pSAH and true subarachnoid hemorrhage (true SAH). A random effects model meta-analysis showed a statistically significant decrease in densities in the Sylvian fissure in patients with pSAH compared to true SAH and a statistically significant decrease in densities in adjacent parenchyma in patients with pSAH compared to true SAH. Systematic review further revealed 32 patients with pSAH associated with spontaneous intracranial hypotension, 11 patients with pSAH related to infectious etiologies, 15 patients with pSAH associated with subdural hemorrhage, 20 cases of pSAH related to hyperhemoglobinemia, 2 cases related to valproate toxicity, and individual cases related to hyponatremia, diabetic ketoacidosis, sudden infant death syndrome, cerebellar infarction, and dialysis disequilibrium syndrome.

Conclusion:

This study is the first systematic review of causes, diagnostic modalities, and outcomes in patients who present with pSAH. A diagnosis of pSAH may be considered following assessment of CT densities following cardiac arrest.

Contrast-induced encephalopathy mimicking total anterior circulation stroke: a case report and review of the literature

INTRODUCTION

Contrast-induced encephalopathy is a rare and usually reversible entity due to the administration of iodinated contrast. Clinical manifestations include cortical blindness, encephalopathy, seizures and focal neurological deficits.

METHODS

We report the case of a 56-year-old woman who developed global aphasia and right hemiplegia after a cerebral angiography performed for a subarachnoid haemorrhage. A prompt brain MRI resulted negative, while CT scan revealed left cerebral oedema with the cerebral sulci effacement. Complete recovery was observed in 10 days.

DISCUSSION

Diagnosis of contrast-induced encephalopathy requires a temporal correlation between neurological dysfunction and administration of iodinated contrast. Usually, the symptomatology is transient with a full recovery within 48-72 h. The most common symptom is cortical blindness, while other symptoms have been rarely reported. Only 20 cases previously reported global aphasia and/or hemiplegia or mimed anterior circulation strokes. Prompt brain neuroimaging is essential in order to exclude an alternative diagnosis that requires a distinct therapeutic approach.

Subarachnoid Contrast Hyperdensity Following Pelvic Trauma Mimicking Diffuse Subarachnoid Hemorrhage

We present a case of a 54-year-old male who was involved in a motorcycle accident. His head computed tomography (CT) scan on arrival at our Level 1 institution was positive for hyperdensity suspicious for subarachnoid hemorrhage (SAH). Spine CT showed anterior compression fractures of T7-T9 vertebral bodies along with the presence of contrast within the subarachnoid space in the thoracic and lumbar spine, raising suspicion for a dural tear. CT of the chest, abdomen, and pelvis revealed open book pelvic fracture, left sacral ala fracture extending into the left sacroiliac joint and S1 neural foramen, coccygeal fracture, and extraperitoneal bladder rupture.

This rare case report highlights the possibility of a spinal meningeal tear in severe pelvic trauma with concomitant bladder injury as a pathway of contrast entry into the normally impermeable cerebrospinal fluid (CSF) space mimicking traumatic subarachnoid hemorrhage.

Pseudo-Subarachnoid Hemorrhage; Chronic Subdural Hematoma with an Unruptured Aneurysm Mistaken for Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) usually occurs due to aneurysmal rupture of intracranial arteries and its typical computed tomography (CT) findings are increased attenuation of cisterns and subarachnoid spaces. However, several CT findings mimicking SAH are feasible in diverse conditions. They are so-called as pseudo-SAH, and this report is a case of pseudo-SAH which is misdiagnosed as aneurysm rupture accompanied by bilateral chronic subdural hematoma (cSDH). A 42-year-old male with severe headache visited our institute. Non-contrast brain CT images showed increased attenuation on basal cistern, and cSDH on both fronto-temporo-parietal convexity with midline shifting. Trans-femoral cerebral angiography was done and we confirmed small aneurysm at right M1 portion of middle cerebral artery. Under diagnosis of SAH, we planned an operation in order to clip aneurysmal neck and remove cSDH. cSDH was removed as planned, however, there was no SAH and we also couldn't find the rupture point of aneurysm. Serial follow-up CT showed mild cumulative cSDH recurrence, but the patient was tolerant and had no neurologic deficit during hospitalization. We have checked the patient via out-patient department for 6 months, there are no significant changes in volume and density of cSDH and the patient also have no neurologic complications.

Nonaneurysmal "Pseudo-Subarachnoid Hemorrhage" Computed Tomography Patterns: Challenges in an Acute Decision-Making Heuristics

BACKGROUND

Acute aneurysmal subarachnoid hemorrhage (SAH) is a medical and neurosurgical emergency from ruptured brain aneurysm. Aneurysmal SAH is identified on brain computed tomography (CT) as increased density of basal cisterns and subarachnoid spaces from acute blood products. Aneurysmal SAH-like pattern on CT appears as an optical illusion effect of hypodense brain parenchyma and/or hyperdense surrounding cerebral cisterns and blood vessels termed as "pseudo-subarachnoid hemorrhage" (pseudo-SAH).

METHODS

We reviewed clinical, laboratory, and radiographic data of all SAH diagnoses between January 2013 and January 2018, and found subsets of nonaneurysmal SAH, originally suspected to be aneurysmal in origin. We performed a National Library of Medicine search methodology using terms "subarachnoid hemorrhage," "pseudo," and "non-aneurysmal subarachnoid hemorrhage" singly and in combination to understand the sensitivity, specificity, and precision of pseudo-SAH.

RESULTS

Over 5 years, 230 SAH cases were referred to our tertiary academic center and only 7 (3%) met the definition of pseudo-SAH. Searching the National Library of Medicine using subarachnoid hemorrhage yielded 27,402 results. When subarachnoid hemorrhage and pseudo were combined, this yielded 70 results and sensitivity was 50% (n = 35). Similarly, search precision was relatively low (26%) as only 18 results fit the clinical description similar to the 7 cases discussed in our series.

CONCLUSIONS

Aneurysmal SAH pattern on CT is distinct from nonaneurysmal and pseudo-SAH patterns. The origin of pseudo-SAH terminology appears mostly tied to comatose cardiac arrest patients with diffuse dark brain Hounsfield units and cerebral edema, and is a potential imaging pitfall in acute medical decision-making.

Clinical Characteristics of Patients with Pseudo-Subarachnoid Haemorrhage who were Successfully Resuscitated from Out-of-Hospital Cardiopulmonary Arrest

Introduction

Pseudo-subarachnoid haemorrhage (PSAH) is a rare neuroradiological finding seen in patients with diffuse cerebral edemas. We investigated clinical characteristics and risk factors for the development of PSAH.

Method

The successfully resuscitated patients in emergency department were classified into two groups: those with pseudo-SAH [PSAH (+)] and those without pseudo-SAH [PSAH (-)]. Clinical variables were analysed.

Results

Pseudo-SAH was found in 31.6% of patients. PSAH was more common in males (p=0.042). The mean age was 39.9±10.3 years in the PSAH (+) group and 54.4±22.0 years in the PSAH (-) group (p=0.038). Outcomes measured by Cerebral Performance Category score were also significantly different between the two groups (p=0.037). Logistic regression analysis found that serum lactate concentration and duration of anoxia were associated with the development of PSAH (with odds ratios and p values of 1.92, p=0.01 and 1.13, p=0.02, respectively).

Conclusions

PSAH itself is a phenomenon that could be seen in post-resuscitation encephalopathy as a consequence of severe anoxic insult.

Reversible and Asymptomatic Gyral and Subarachnoid Contrast Enhancement after Carotid Stenting

The presence of sulcal hyperdensity in patients after endovascular procedures is not necessarily attributable to hemorrhage. It may frequently indicate the absolute or concomitant extravasation of contrast material into the subarachnoid spaces.This case report describes the clinical case of an 84-year-old patient with 90% stenosis of the right internal carotid who presented with a diffuse gyral and sulcal hyperdensity in the right temporal-occipital and frontal lobes at routine post-carotid stenting (CAS) brain CT scan. The patient was asymptomatic and CT findings were interpreted as contrast enhancement hyperattenuation and no therapeutic decisions were made. A 24-hour follow-up brain CT demonstrated the complete resolution of the hyperdensity, confirming the diagnosis.In this patient we considered the concomitant presence of gyral and sulcal hyperdensity as the consequence of reversible damage to the blood-brain barrier (BBB) determining a transitory extravasation of contrast material. Asymptomatic gyral and subarachnoid contrast enhancement following CAS is generally indicative of benign and transitory damage to the BBB and is not to be misinterpreted as hemorrhage.

Hyperdense large artery sign in meningitis: A marker of ominous thrombogenic potential of pneumococcus?

Hyperdensity in the middle cerebral artery (MCA) or posterior cerebral artery (PCA) on non-contrast head CT, suggests the presence of a thrombus inside these vessels, often referred to as the “MCA sign” or “PCA sign” respectively. These two signs are classically associated with strokes secondary to cardiovascular etiologies and are only infrequently reported with other types of stroke. Whereas stroke is a recognized complication of pneumococcal meningitis hyperdense large vessel sign (in this case a combination of MCA and PCA) has not been previously reported. We report a case of rapidly progressive pneumococcal meningitis that presented as acute stroke involving large vessels in the vicinity of the circle of Willis in a patient with a history of non-Hodgkin lymphoma (NHL) in remission for 6 years. This patient had received a week of high dose steroids before admission. Head CT scan on admission showed the presence of hyperdense MCA and PCA signs. The patient rapidly deteriorated and a follow-up head CT revealed diffuse brain edema and increased density in the basal cisterns without evidence of sub arachnoid hemorrhage. Tc99m exametazime brain flow scan showed no intracerebral blood flow both supra and infratentorially. Steptococcus pneumoniae, NHL cells and high-dose steroid use can upregulate tissue factor synthesis and may have led to a hypercoagulable state via activation of the extrinsic pathway in the large intracerbral arteries.

Cerebral contrast retention after difficult cardiac catheterization: Case report

Background:

We report a diagnostic dilemma in a rare case of cerebral contrast retention after difficult cardiac catheterization in an elderly patient loaded with prasugrel.

Summary:

Our case report describes a 77-year-old female with history of hypertension, diabetes, and dyslipidemia who presented to emergency department complaining of chest pain. Patient was found to have an inferior wall ST elevation myocardial infarction. The patient was loaded with aspirin and prasugrel and taken for emergent cardiac catheterization. Cardiac catheterization revealed two-vessel coronary artery disease with unsuccessful attempt of percutaneous intervention. Immediately after procedure, patient developed an episode of seizure. Emergent computed tomography scan of the brain revealed hyperdensity in the right frontoparietal region consistent with intracerebral bleed. Repeat computed tomography (24 h later) revealed substantial interval improvement of hyperdensity. Follow-up magnetic resonance imaging of the head was normal. Given the lack of magnetic resonance imaging changes, the rate of resolution on computed tomography without expected subacute changes, and the lack of neurologic findings, the initial hyperdensity seen on computed tomography of the brain was believed to be secondary to contrast leakage during cardiac catheterization as opposed to intracranial hemorrhage.

Contrast mimicking a subarachnoid hemorrhage after lumbar percutaneous epidural neuroplasty: a case report

Introduction

Subarachnoid hemorrhage is one of the most feared acute neurologic events. Accurate diagnosis of subarachnoid hemorrhage is essential, and computed tomography of the brain is the first diagnostic imaging study. However, in rare circumstances, a similar appearance may occur in the absence of blood in the subarachnoid space. The contrast enhancement of subarachnoid space is a rare complication after lumbar percutaneous epidural neuroplasty, with, to the best of our knowledge, no previous report in the literature.

Case presentation

A 42-year-old Korean male patient, who underwent a spinal operation five years previously at the level of L4 to S1, visited our clinic with persistent and aggravating low back pain. An imaging study revealed the focal and diffuse disc protrusion at the level of L4/5 and L5/S1. The clinician decided to perform a lumbar percutaneous epidural neuroplasty. During the procedure, dural adhesion was suspected at the previously operated level, and the neuroplasty catheter was malpositioned into the intradural space on the first attempt. After the catheter was repositioned, the scheduled epidural neuroplasty was completed. Our patient had no definite abnormal neurological signs. But, after a day, our patient complained of severe headache with sustained high blood pressure without neurological disorientation. Computed tomography of his brain showed a subarachnoid hemorrhage-like appearance with intracranial air. Sequential angiography, subtractional magnetic resonance imaging and examination of the cerebrospinal fluid revealed no abnormalities. Follow-up computed tomography after one day revealed no definite intracranial hemorrhage, and our patient was discharged with improved low back pain without neurological deficit.

Conclusion

We report a rare case of contrast mimicking a subarachnoid hemorrhage after lumbar percutaneous epidural neuroplasty. The physician should keep in mind a rare case like this, and the supine position with head elevation is necessary to avoid a similar complication after lumbar percutaneous epidural neuroplasty.

Subarachnoid hemorrhage mimicking leakage of contrast media after coronary angiography

We report a patient who developed subarachnoid hemorrhage (SAH) just after coronary angiography (CAG) with non-ionic contrast media (CM) and minimal dose of heparin. The 55-year-old man had a history of acute ST elevation myocardial infarction that had been treated with primary percutaneous coronary intervention and was admitted for a follow-up CAG. The CAG was performed by the transradial approach, using 1000 U of unfractionated heparin for the luminal coating and 70 mL of iodixanol. At the end of CAG, he complained of nausea and rapidly became stuporous. Brain CT showed a diffusely increased Hounsfield unit (HU) in the cisternal space, similar to leakage of CM. The maximal HU was 65 in the cisternal space. No vascular malformations were detected on cerebral angiography. The patient partially recovered his mental status and motor weakness after 2 days. Two weeks later, subacute SAH was evident on magnetic resonance imaging. The patient was discharged after 28 days.

Persistent neurological deficit from iodinated contrast encephalopathy following intracranial aneurysm coiling. A case report and review of the literature

Neurotoxicity from iodinated contrast agents is a known but rare complication of angiography and neurovascular intervention. Neurotoxicity results from contrast penetrating the blood-brain barrier with resultant cerebral oedema and altered neuronal excitability. Clinical effects include encephalopathy, seizures, cortical blindness and focal neurological deficits. Contrast induced encephalopathy is extensively reported as a transient and reversible phenomenon. We describe a patient with a persistent motor deficit due to an encephalopathy from iodinated contrast media administered during cerebral aneurysm coiling. This observation and a review of the literature highlights that contrast-induced encephalopathy may not always have a benign outcome and can cause permanent deficits. This potential harmful effect should be recognised by the angiographer and the interventionalist.

Large subdural effusions after angiography mimicking acute subdural hematoma

Contrast enhancement of the brain parenchyma and ventricular and subarachnoidal contrast extravasation are known to be rare complications after intra-arterial angiography. We here describe the first case of extensive contrast extravasation into the subdural space after percutaneous coronary intervention.

Cryptococcal meningitis presenting as pseudosubarachnoid hemorrhage

A 50-year-old man presented with progressive visual loss, headache, and two days of confusion. A computed tomography of his head suggested subarachnoid hemorrhage with accompanying right parietal ischemic infarction. The magnetic resonance image was consistent with right parietal perisulcal pial and superficial cortical inflammation; a subjacent vasogenic edema with a 1 cm diameter abscess was also present. Funduscopy revealed bilateral multifocal choroidal lesions and retinal perivascular sheathing. He was diagnosed with pseudosubarachnoid hemorrhage secondary to cryptococcal meningitis and choroidal microabscesses with retinal inflammation after a cerebrospinal fluid (CSF) examination revealed cryptococcal yeast forms, as well as high titers of CSF cryptococcal antigen, but no CSF red blood cells.

The conundrum of transient cortical blindness following coronary angiography

We report a case of transient cortical blindness that occurred after coronary angiography and angioplasty performed through the right radial artery. This is a very rare entity, the physiopathology of which remains largely speculative. The most likely mechanism appears to be the local disruption of the blood-brain barrier by the contrast agent, possibly favoured by predisposing factors, which may cause a direct neurotoxic effect. All contrast agents can be associated with this complication, which does not seem to be volume dependent. The outcome is generally favourable, with spontaneous return of sight within 24-48 h and no requirement for specific therapy. Recurrence has never been reported.

Contrast enhancement hyperdensity after endovascular coiling of intracranial aneurysms

BACKGROUND AND PURPOSE

Endovascular coil embolization is used increasingly to treat cerebral aneurysms. The purpose of our study was to quantify the incidence of CT-detectable abnormalities after aneurysm coiling and map the radiographic and clinical progression.

MATERIALS AND METHODS

We reviewed the radiographic and clinical sequelae of 30 consecutive patients with aneurysms who underwent endosaccular coiling followed by head CT scans. Patients with CT abnormalities received follow-up scans at 4 to 6 hours and 20 to 25 hours. Contrast enhancement was defined as CT hyperdensities with progressive resolution over 25 hours and a Hounsfield unit (HU) of less than 70. The incidence of CT abnormalities was recorded and correlated with amount of contrast used, use of antiplatelet agents, procedure time, and clinical sequelae.

RESULTS

Seven patients (23%) had new hyperdensities on CT scan. Four showed gyral hyperattenuation; 1 showed basal ganglia hyperattenuation, and 2 showed a combination of these patterns. All were asymptomatic and were consistent with contrast enhancement, with complete resolution in 5 of 7 and partial resolution in 2 of 7 by 20 to 25 hours. Antithrombotic or antiplatelet medication was continued in all cases. The amount of contrast used (P = .014) and the use of antiplatelet medication (P = .029) were statistically correlated with the presence of hyperattenuation after aneurysm coiling, whereas the length of the procedure was not (P = .162).

CONCLUSION

Contrast enhancement, unlike contrast extravasation, is a fairly common and clinically benign finding after aneurysm coiling. The enhancement resolves by 25 hours in most cases, regardless of the continuation of antithrombotic or antiplatelet therapy.

Immediate CT findings following embolization of cerebral aneurysms: suggestion of blood-brain barrier or vascular permeability change

INTRODUCTION

Although endovascular techniques are widely used for the treatment of cerebral aneurysms, the immediate postprocedural brain CT findings have not been reported. Therefore, in the present study we assessed the immediate postprocedural brain CT findings following the uneventful coil embolization of cerebral aneurysms.

METHODS

Included in the study were 59 patients with 61 cerebral aneurysms after uncomplicated coil embolization. Acute subarachnoid hemorrhage was present with 32 of the 61 aneurysms. All patients underwent a brain CT scan just before and within 2 h after the endovascular treatment. If the postprocedural CT scan revealed any new findings, a follow-up CT scan and/or MRI were performed within 24 h. The variables related to the abnormal CT findings were also evaluated.

RESULTS

Among the 61 immediate brain CT scans, 26 (43%) showed abnormal findings, including cortical contrast enhancement (n=21, 34%), subarachnoid contrast enhancement (n=8, 13%), intraventricular contrast enhancement (n=5, 8%), and striatal contrast enhancement (n=2, 3%). Single or mixed CT findings were also seen. None of the 61 aneurysms was associated with new neurological symptoms after endovascular treatment, and all patients made an uneventful recovery. Abnormal findings were more likely to be found with lower body weight and with increased corrected amounts of contrast material and heparin (P<0.05).

CONCLUSION

After uneventful endovascular treatment of cerebral aneurysms, the immediate brain CT findings can reveal various patterns of abnormal contrast enhancement. Recognizing the immediate brain CT findings is important, as they can mimic various diseases.

Extensive cerebrospinal fluid enhancement following gadolinium chelate administration: possible pathogenesis

Diffuse cerebrospinal fluid (CSF) enhancement following gadolinium administration is a rarely recognized phenomenon, and its mechanism is not fully understood. We report two cases of diffuse CSF enhancement following gadolinium administration and review the literature. We conclude that the contributing factors of this phenomenon include blood-CSF barrier disruption, increased dosage, impair renal clearance, delayed imaging after contrast administration, and use of different pulse sequences.

Transient partial amnesia complicating cardiac and peripheral arteriography with nonionic contrast medium

The aim of this study was to present a case of disruption of the blood-brain barrier during the coronary and lower extremity angiographies with radiological and clinical findings. This condition was secondary to intraarterial use of a nonionic, monomeric contrast medium. A total of 450 cc contrast media was used. Computed tomography examination showed contrast enhancement of the right occipital and frontoparietal cortical regions, which returned to normal one day after. The patient also fully recovered from the neurological symptoms within 24 h. We discussed the possible mechanism for blood-brain barrier disruption in this case.

False subarachnoid hemorrhage in anoxic encephalopathy with brain swelling

The authors present two comatose patients with brain swelling from anoxic encephalopathy. Nonenhanced computed tomography (CT) images showed increased density on the falx, on the tentorium, and in the basal cisterns, all of which falsely suggested subarachnoid hemorrhage. Autopsy in both patients failed to show subarachnoid hemorrhage. In rare circumstances, anoxic encephalopathy can mimic subarachnoid hemorrhage on nonenhanced CT.