Follow-up Non-contrast CT Research Articles

Ischemic Stroke in Evolution: Predictive Value of Perfusion Computed Tomography

Various perfusion computed tomography (PCT) parameters have been used to identify tissue at risk of infarction in the setting of acute stroke. The purpose of this study was to examine predictive value of the PCT parameters commonly used in clinical practice to define ischemic penumbra. The patient selection criterion aimed to exclude the effect of thrombolysis from the imaging data. Consecutive acute stroke patients were screened and a total of 18 patients who initially underwent PCT and CT angiogram (CTA) on presentation but did not qualify to receive thrombolytic therapy were selected. The PCT images were postprocessed using a delay-sensitive deconvolution algorithm. All the patients had follow-up noncontrast CT or magnetic resonance imaging to delineate the extent of their infarction. The extent of lesions on PCT maps calculated from mean transit time (MTT), time to peak (TTP), cerebral blood flow, and cerebral blood volume were compared and correlated with the final infarct size. A collateral grading score was used to measure collateral blood supply on the CTA studies. The average size of MTT lesions was larger than infarct lesions (P < .05). The correlation coefficient of TTP/infarct lesions (r = .95) was better than MTT/infarct lesions (r = .66) (P = .004). A widely accepted threshold to define MTT lesions overestimates the ischemic penumbra. In this setting, TTP with appropriate threshold is a better predictor of infarct in acute stroke patients. The MTT/TTP mismatch correlates with the status of collateral blood supply to the tissue at risk of infarction.

Deep coma and diffuse white matter abnormalities caused by sepsis-associated encephalopathy

In January, 2012, a 53-year-old woman with a history of progressive polyposis coli and hypertension was admitted to the intensive care unit (ICU) of our hospital because of septic shock 4 days after laparoscopic subtotal colectomy. She was intubated and mechanically ventilated, underwent emergent re-laparotomy for anastomotic leakage, and was treated with antibiotics. Blood cultures were positive for multiresistant Enterococcus faecium. After re-laparotomy the patient was sedated with midazolam for 2 days. The neurologist was consulted on the fourth postoperative day because of the patient’s persistent low level of consciousness. On neurological examination, we found no eye opening or motor response to a painful stimulus, intact brainstem refl exes, and generalised arefl exia of arms and legs with indiff erent plantar refl exes. We observed no signs indicative of minimally convulsive status epilepticus. During the period of septic shock and surgery, blood pressure had not been lower than 100/50 mm Hg and laboratory tests did not show abnormalities that could explain the patient’s coma. Non-contrast CT (NCCT) of the brain showed abnormal hypodensity of the complete white matter with swelling of the entire brain (fi gure); CT angiography was normal. Electromyography showed absence of motor unit potentials in arm and leg muscles without evidence for accompanying neuropathy. We made a diagnosis of sepsis-associated encephalopathy and critical illness myopathy. Because of the deep coma and the diff use and severely abnormal aspect of the white matter—both associated with poor outcome—dis continuation of treatment was discussed, but we recommended to continue treatment. On the ninth postoperative day the patient opened her eyes in response to painful stimuli, but there was still no motor response. Follow-up NCCT showed no improvement of the white matter abnormalities. In the following weeks the condition of the patient gradually improved and 4 weeks after the re-laparotomy she had regained full consciousness. When the patient was discharged from the ICU her muscle strength had gradually improved with movements against gravity now possible. At that time brain MRI was normal except for a small number of white matter lesions (fi gure). The patient was transferred to a rehabilitation centre 6 weeks after the initial onset of septic shock. At that point she was able to walk short distances. At last follow-up on Aug 19, 2012, she had regained independence in activities of daily living and was living at home. Sepsis-associated encephalopathy is a severe complication of sepsis and is associated with poor outcome. The reported incidence ranges from 9% to 71% because of variations in the defi nition. A recent study in an ICU showed that patients with sepsis secondary to intestinal infections are prone to develop septic encephalopathy, with Escherichia coli and Enterococcus faecium among the most frequently cultured bacteria. The exact pathogenesis of sepsis-associated encephalopathy remains unclear; disruption of the blood-brain barrier and mitochondrial dysfunction are probably involved. Imaging of the brain can show atrophy and periventricular white matter lesions. The diff use and severe white matter abnormalities like those we observed in our patient are rare and have been associated with poor outcome. This case shows that severe encephalopathy with extensive white matter lesions can be a reversible condition. Clinicians should realise that the fi rst signs of improvement of the clinical condition could still be observed beyond 7 days after onset.

Brain CT perfusion provides additional useful information in severe traumatic brain injury

BackgroundThe role of brain CT perfusion (CTP) imaging in severe traumatic brain injury (STBI) is unclear. We hypothesised that in STBI early CTP may provide additional information beyond the non contrast CT (NCCT). MethodsSubset analysis of an ongoing prospective observational study on trauma patients with STBI who did not require craniectomy and deteriorated or failed to improve neurologically during the first 48h from trauma. Subsequently to follow-up NCCT, a CTP was obtained. Additional findings were defined as an area of altered perfusion on CTP larger than the abnormal area detected by the simultaneous NCCT. Patients who had additional finding (A-CTP) were compared with patients who did not have additional findings (NA-CTP). ResultsStudy population was 30 patients [male: 90%, mean age: 38.6 (SD 16.9), blunt trauma: 100%; prehospital intubation: 6 (20%); lowest GCS before intubation: 5.1 (SD 2.0); mean ISS: 30.5 (SD 8.3); mean head and neck AIS: 4.4 (SD 0.8). Days in ICU: 10.2 (SD 6.3). Intracranial pressure (ICP) monitored in 12 (40%). Mean highest ICP in mmHg: 30.1 (SD14.1). There were five (17%) deaths. Findings of NCCT: primarily diffuse axonal injury (DAI) pattern in seven (23%), primarily haematoma in ten (33%), and primarily intracerebral contusion in nine (30%). CTP was performed 24.9 (SD 13) hours from trauma. There were 18 (60%) patients in the A-CTP group and 12 (40.0%) in NA-CTP. The A-CTP group was older (41.7 (SD16.9) vs 27.7 (SD 12.8): P<0.02) and showed on admission NCCT presence of cerebral contusion and absence of DAI. The degree of hypoperfusion was found to be severe enough to be in the ischaemic range in eight patients (27%). CTP altered clinical management in three patients (10%), who were diagnosed with massive and unsurvivable strokes despite minimal changes on NCCT. ConclusionWhen compared to NCCT, CTP provided additional diagnostic information in 60% of patients with STBI. CTP altered clinical management in 10% of patients.

Automated Cerebral Infarct Volume Measurement in Follow-up Noncontrast CT Scans of Patients with Acute Ischemic Stroke

Cerebral infarct volume as observed in follow-up CT is an important radiologic outcome measure of the effectiveness of treatment of patients with acute ischemic stroke. However, manual measurement of CIV is time-consuming and operator-dependent. The purpose of this study was to develop and evaluate a robust automated measurement of the CIV. The CIV in early follow-up CT images of 34 consecutive patients with acute ischemic stroke was segmented with an automated intensity-based region-growing algorithm, which includes partial volume effect correction near the skull, midline determination, and ventricle and hemorrhage exclusion. Two observers manually delineated the CIV. Interobserver variability of the manual assessments and the accuracy of the automated method were evaluated by using the Pearson correlation, Bland-Altman analysis, and Dice coefficients. The accuracy was defined as the correlation with the manual assessment as a reference standard. The Pearson correlation for the automated method compared with the reference standard was similar to the manual correlation (R = 0.98). The accuracy of the automated method was excellent with a mean difference of 0.5 mL with limits of agreement of -38.0-39.1 mL, which were more consistent than the interobserver variability of the 2 observers (-40.9-44.1 mL). However, the Dice coefficients were higher for the manual delineation. The automated method showed a strong correlation and accuracy with the manual reference measurement. This approach has the potential to become the standard in assessing the infarct volume as a secondary outcome measure for evaluating the effectiveness of treatment.

Early Parenchymal Contrast Extravasation Predicts Subsequent Hemorrhage Progression, Clinical Deterioration, and Need for Surgery in Patients With Traumatic Cerebral Contusion

This study aimed to identify early radiologic signs that are predictive of hemorrhage progression and clinical deterioration in patients with traumatic cerebral contusion. We hypothesized that contrast extravasation (CE) and blood-brain barrier disruption might be associated with hemorrhage progression, brain edema, and clinical deterioration in these patients. Twenty-two patients with traumatic cerebral contusion (diagnosed on initial noncontrast head computed tomography [CT]) who initially did not require surgical intervention were enrolled in this study. Contrast-enhanced and perfusion CT scans were performed within 6 hours of injury, and follow-up noncontrast CT scans were performed at 24 hours and 72 hours. In each noncontrast CT scan, the volumes of the contusion hemorrhage and edema were calculated using computerized planimetric techniques. The initial Glasgow Coma Scale, hemorrhage progression, clinical deterioration, and the need for subsequent surgery were recorded. The early radiologic findings were compared with these parameters and functional outcome at 6 months to identify predictive radiologic signs. CE was present in 9 of 22 patients (41%) and was highly associated with hemorrhage progression (p < 0.05), clinical deterioration (p < 0.01), and need for subsequent surgery (p < 0.01). In addition, patients with CE had a greater volume of edema at 24 hours (p < 0.01) and 72 hours (p < 0.01) than those who did not have CE. However, CE was not found to be associated with poor outcome. Early parenchymal CE is associated with hemorrhage progression, cerebral edema, clinical deterioration, and need for subsequent surgery. These patients should be monitored closely, and early surgery may be needed if deterioration occurs. Further elucidation of the pathophysiology is needed to formulate effective treatment for these high-risk patients.

Contrast Extravasation on Computed Tomography Angiography Predicts Clinical Outcome in Primary Intracerebral Hemorrhage

Several retrospective studies suggested that contrast extravasation on CT angiography predicts hematoma expansion, poor outcome, and mortality in primary intracerebral hemorrhage. We aimed to determine the predictive value of contrast extravasation on multidetector CT angiography for clinical outcome in a prospective study. In 160 consecutive patients with spontaneous intracerebral hemorrhage admitted within 6 hours of symptom onset, noncontrast CT and multidetector CT angiography were performed on admission. A follow-up noncontrast CT was done at 24 hours. Multidetector CT angiography images were analyzed to identify the presence of contrast extravasation. Clinical outcome was assessed by modified Rankin Scale on discharge and at 90 days. A total of 139 patients with primary intracerebral hemorrhage were included in the final analysis. Contrast extravasation occurred in 30 (21.6%) patients. The presence of contrast extravasation was associated with increased hematoma expansion (P<0.0001), in-hospital mortality (P=0.008), prolonged hospital stay (P=0.006), poor outcome on discharge (P=0.025), increased 3-month mortality (P=0.009), and poor clinical outcome (P<0.0001). In multivariate analysis, contrast extravasation was a promising independent predictor (OR, 10.5; 95% CI, 3.2-34.7; P<0.0001) for 90-day poor clinical outcome followed by the presence of intraventricular hemorrhage (OR, 3.4; 95% CI, 1.5-7.7; P=0.003) and initial hematoma volume (OR, 1.0; 95% CI, 1.0-1.1; P=0.013). The presence of contrast extravasation on multidetector CT angiography in patients with hyperacute-stage intracerebral hemorrhage is an independent and strong factor associated with poor outcome. Any patient with intracerebral hemorrhage with such sign on multidetector CT angiography should be monitored intensely and treated accordingly.

Persistent renal enhancement after intra-arterial versus intravenous iodixanol administration

To examine the clinical significance of persistent renal enhancement after iodixanol administration. We retrospectively studied 166 consecutive patients who underwent non-enhanced abdominopelvic CT within 7 days after receiving intra-arterial (n=99) or intravenous (n=67) iodixanol. Renal attenuation was measured for each non-enhanced CT scan. Persistent renal enhancement was defined as CT attenuation>55 Hounsfield units (HU). Contrast-induced nephropathy (CIN) was defined as a rise in serum creatinine>0.5 mg/dL within 5 days after contrast administration. While the intensity and frequency of persistent renal enhancement was higher after intra-arterial (mean CT attenuation of 73.7 HU, seen in 54 of 99 patients, or 55%) than intravenous contrast material administration (51.8 HU, seen in 21 of 67, or 31%, p<0.005), a multivariate regression model showed that the independent predictors of persistent renal enhancement were a shorter time interval until the subsequent non-enhanced CT (p<0.001); higher contrast dose (p<0.001); higher baseline serum creatinine (p<0.01); and older age (p<0.05). The route of contrast administration was not a predictor of persistent renal enhancement in this model. Contrast-induced nephropathy was noted in 9 patients who received intra-arterial (9%) versus 3 who received intravenous iodixanol (4%), and was more common in patients with persistent renal enhancement (p<0.01). Persistent renal enhancement at follow-up non-contrast CT suggests a greater risk for contrast-induced nephropathy, but the increased frequency of striking renal enhancement in patients who received intra-arterial rather than intravenous contrast material also reflects the larger doses of contrast and shorter time to subsequent follow-up CT scanning for such patients.

Perfusion CT Imaging Follows Clinical Severity in Left Hemispheric Strokes

Objective: The purpose of this study was to assess how imaging findings on admission perfusion CT (PCT) and follow-up noncontrast CT (NCT), and their changes over time, correlate with clinical scores of stroke severity measured on admission, at discharge and at 6-month follow-up. Methods: Fifty-two patients with suspected hemispheric acute ischemic stroke underwent a PCT within the first 24 h of symptom onset and a follow-up NCT of the brain between 24 h and 3 months after the initial stroke CT study. NIH Stroke Scale (NIHSS) scores were recorded for each patient at admission, discharge and 6 months; modified Rankin scores were determined at discharge and 6 months. Baseline PCT and follow-up NCT were analyzed quantitatively (volume of ischemic/infarcted tissue) and semiquantitatively (anatomical grading score derived from the Alberta Stroke Program Early CT Score). The correlation between imaging volumes/scores and clinical scores was assessed. Analysis was performed for all patients considered together and separately for those with right and left hemispheric strokes. Results: Significant correlations were found between clinical scores and both quantitative and semiquantitative imaging. The volume of the acute PCT mean transit time lesion showed best correlation with admission NIHSS scores (R² = 0.61, p < 0.001). This association was significantly better for left hemispheric strokes (R² = 0.80, p < 0.001) than for right hemispheric strokes (R² = 0.39, p = 0.131). Correlation between imaging and NIHSS scores was better than correlation between imaging and modified Rankin scores (p = 0.047). The correlation with discharge clinical scores was better than that with 6-month clinical scores (p = 0.012). Conclusions: Baseline PCT and follow-up NCT volumes predict stroke severity at baseline, discharge and, to a lesser extent, 6 months. The correlation is stronger for left-sided infarctions. This finding supports the use of PCT as a surrogate stroke outcome measure.

Contrast Extravasation on CT Predicts Mortality in Primary Intracerebral Hemorrhage

Recent studies of intracerebral hemorrhage (ICH) treatments have highlighted the need to identify reliable predictors of hematoma expansion. The goal of this study was to determine whether contrast extravasation on multisection CT angiography (CTA) and/or contrast-enhanced CT (CECT) of the brain is associated with hematoma expansion and increased mortality in patients with primary ICH. All patients with primary ICH who underwent CTA and CECT, as well as follow-up noncontrast CT (NCCT) before discharge/death from January 1, 2003, to September 30, 2005, were retrospectively identified. One neuroradiologist reviewed admission and follow-up NCCT for hematoma size and growth. A second neuroradiologist independently reviewed CTA and CECT for active contrast extravasation. Univariate and multivariate logistic regression analyses were performed to evaluate the significance of clinical and radiologic variables in predicting 30-day mortality, designated as the primary outcome. Hematoma growth was considered as a secondary outcome. Of 56 patients, contrast extravasation was seen in 17.9% of patients on initial CTA and in 23.2% of patients on initial CECT following CTA. Univariate analysis showed that the presence of extravasation on CT, large initial hematoma size (>30 mL), the presence of "swirl sign" on NCCT, the Glasgow Coma Scale and ICH scores, and international normalized ratio were associated with increased mortality. On multivariate analysis, only contrast extravasation on CT (P = .017) independently predicted mortality. Contrast extravasation on CT (P < .001) was also an independent predictor of hematoma growth on multivariate analysis. Active contrast extravasation on CT in patients with primary ICH independently predicts mortality and hematoma growth.

Alberta Stroke Program Early CT Scoring of CT Perfusion in Early Stroke Visualization and Assessment

Qualitative CT perfusion (CTP) assessment by using the Alberta Stroke Program Early CT Score (ASPECTS) allows rapid calculation of infarct extent for middle cerebral artery infarcts. Published thresholds exist for noncontrast CT (NCCT) ASPECTS, which may distinguish outcome/complication risk, but early ischemic signs are difficult to detect. We hypothesized that different ASPECTS thresholds exist for CTP parameters versus NCCT and that these may be superior at predicting clinical and radiologic outcome in the acute setting. Thirty-six baseline acute stroke NCCT and CTP studies within 3 hours of symptoms were blindly reviewed by 3 neuroradiologists, and ASPECTS were assigned. Treatment response was defined as major neurologic improvement when a > or =8-point National Institutes of Health Stroke Scale improvement at 24 hours occurred. Follow-up NCCT ASPECTS and 90-day modified Rankin score (mRS) were radiologic and clinical reference standards. Receiver operating characteristic curves derived optimal thresholds for outcome. Cerebral blood volume and NCCT ASPECTS had similar radiologic correlations (0.6 and 0.5, respectively) and best predicted infarct size in the absence of major neurologic improvement. A NCCT ASPECT threshold of 7 and a cerebral blood volume threshold of 8 discriminated patients with poor follow-up scans (P < .0002 and P = .0001) and mRS < or =2 (P = .001 and P < .001). Only cerebral blood volume predicted major neurologic improvement (P = .02). Interobserver agreement was substantial (intraclass correlation coefficient, 0.69). Cerebral blood volume ASPECTS sensitivity, specificity, positive predictive value, and negative predictive value for clinical outcome were 60%, 100%, 100%, and 45%, respectively. No patients with cerebral blood volume ASPECTS <8 achieved good clinical outcome. Cerebral blood volume ASPECTS is equivalent to NCCT for predicting radiologic outcome but may have an additional benefit in predicting patients with major neurologic improvement.

Occlusive vascular disease in asphyxiated newborn infants

Six full-term severely asphyxiated newborn infants underwent evaluation with digital intravenous angiography. All infants were comatose and flaccid and had seizures, depressed brainstem function, and signs of intracranial hypertension. An initial brain CT scan revealed diffuse hypodensities and compressed ventricles. Follow-up noncontrast CT scans showed areas of increased attenuation. Digital intravenous angiography demonstrated venous sinus thrombosis in five infants, two of whom also had arterial thrombosis, and hypervascularity in the sixth infant. Our data document that occlusive vascular disease is a prominent feature of severe perinatal asphyxia.