Improvement in cerebral hemodynamic parameters and outcomes after superficial temporal artery-middle cerebral artery bypass in patients with severe stenoocclusive disease of the intracranial internal carotid or middle cerebral arteries

OBJECT

Both the older and the recent extracranial-intracranial (EC-IC) bypass trials for symptomatic carotid occlusion failed to demonstrate a reduction in stroke recurrence. However, the role of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in patients with symptomatic intracranial stenoocclusive disease has been rarely evaluated. The authors evaluated serial changes in various cerebral hemodynamic parameters in patients with severe stenoocclusive disease of the intracranial internal carotid artery (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR), treated by STA-MCA bypass surgery or medical treatment.

METHODS

Patients with severe stenoocclusive disease of the intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using the breath-holding index (BHI). Patients with impaired BHI (< 0.69) were further evaluated with acetazolamide-challenge technitium-99m hexamethylpropyleneamine oxime ((99m)Tc HMPAO) SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent TCD and SPECT at 4 ± 1 months and were followed up for cerebral ischemic events.

RESULTS

A total of 112 patients were included. This total included 73 men, and the mean age of the entire study population was 56 years (range 23-78 years). (99m)Tc HMPAO SPECT demonstrated impaired CVR in 77 patients (69%). Of these 77 patients, 46 underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenge (99m)Tc HMPAO SPECT repeated at 4 ± 1 months showed significant improvement in the STA-MCA bypass group. During a mean follow-up of 34 months (range 18-39 months), only 6 (13%) of 46 patients in the bypass group developed cerebral ischemic events, as compared with 14 (45%) of 31 patients receiving medical therapy (absolute risk reduction 32%, p = 0.008).

CONCLUSIONS

STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial stenoocclusive disease of the intracranial ICA or MCA results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

Abstract 74: Improvement in Cerebral Hemodynamic Parameters and Outcome after Superficial Temporal Artery- Middle Cerebral Artery Bypass in Patients with Severe Steno-occlusive Disease of Intracranial Carotid and Middle Cerebral Artery

Background and Objective: Older and the recent extracranial-intracranial (EC/IC) bypass trials for symptomatic carotid occlusion failed to demonstrate reduction in stroke recurrence. However, role of superficial temporal artery-middle cerebral artery (STA-MCA) bypass in patients with symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We evaluated serial changes in various cerebral hemodynamic parameters in patients with severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR), treated with STA-MCA bypass surgery or medical treatment.

Methods: Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using breath-holding index (BHI). Patients with impaired BHI (<0.69) were further evaluated with acetazolamide-challenged hexamethylpropyleneamine-oxime single-photon emission computed tomography (HMPAO-SPECT). STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent TCD and SPECT at 4±1 months and followed-up for cerebral ischemic events.

Results: A total of 112patients (73males, mean age 56yrs; range 23-78yrs) were included. HMPAO-SPECT demonstrated impaired CVR in 77 (69%) patients. Of them, 46 underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenged HMPAO-SPECT repeated 4±1months showed significant improvement in STA-MCA bypass group. During follow-up (mean 34months; range 18-39months), only 6/46 (13%) patients in bypass group developed cerebral ischemic events as compared to 14/31 (45%) cases on medical therapy (absolute risk-reduction 32%, p=0.008).

Conclusion: STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial steno-occlusive disease results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

Abstract T MP29: Impaired Vasodilatory Reserve on Acetazolamide-Challenged 99tc-hmpao-Spect is a Strong Predictor of Stroke Recurrence in Patients With Severe Steno-Occlusive Disease of Intracranial Carotid or Middle Cerebral Artery

Background: Intracranial stenosis carries an increased risk for cerebrovascular ischemia. In severe stenosis, cerebral autoregulation may be impaired due to inadequate cerebral vasodilatory reserve (CVR) & intracranial steal phenomenon (reversed-Robin Hood syndrome-RRHS). Identification of patients with inadequate CVR and RRHS may help in identifying high-risk patients.

Methods: In this prospective study, we included patients with symptomatic and severe stenosis of intracranial carotid (ICA) & middle cerebral artery (MCA). CVR was evaluated with transcranial Doppler (TCD) and breath-holding index (BHI) <0.69 determined inadequate CVR. RRHS was detected as transient velocity reduction in affected artery when flow increased in the reference artery. Patients with RRHS were further evaluated with acetazolamide-challenged 99Tc-HMPAO-SPECT.

Results: 126 patients (80 male, mean age 56yrs; range 23-78yrs) fulfilled our TCD criteria for inadequate CVR. HMPAO-SPECT showed impaired CVR in 84 (67%) patients. RRHS noted on TCD in 38 (45%) patients (median steal magnitude 14%; inter-quartile range, IQR 10) was confirmed by acetazolamide-challenged HMPAO-SPECT (median perfusion deficit 8%; IQR 13%) in 35 (92%) cases (sensitivity 82%, specificity 96% with positive predictive value 96%). A strong relationship between RRHS on TCD and SPECT was noted on ROC curve analysis (area under curve 0.93; 95% confidence interval 0.87-0.98;p<0.00001). Linear relationship was observed between impaired vasodilatory reserve and stroke recurrence during follow up (mean 35months; range 8 to 49months)- 56% in patients with RRHS versus 20% in patients with moderately impaired CVR versus 4% in patients with mildly impaired CVR (chi-square 18.42; df=2; p<0.001 for trend). RRHS on HMPAO-SPECT was an independent predictor of recurrent cerebral ischemic events (RR 1.9, 95%CI 1.2-4.2; p=0.03).

Conclusions: Among patients with severe intracranial stenosis, intracranial steal phenomenon is associated with high risk of cerebral ischemic events. Acetazolamide-challenged HMPAO-SPECT is reliable in the quantification of vasodilatory reserve for selecting a target group of patients for possible revascularization.

Abstract T MP26: Role of 99tc-hmpao Spect in the Assessment of Cerebral Hemodynamic Parameters After Superficial Temporal Artery- Middle Cerebral Artery Bypass in Patients With Severe Steno-Occlusive Disease of Intracranial Carotid and Middle Cerebral Artery

Background and Objective: Although superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery in patients with symptomatic carotid occlusion failed to demonstrate any benefit, its role in symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We evaluated changes in hemodynamic parameters in patients with severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) who underwent STA-MCA bypass for impaired cerebral vasodilatory reserve (CVR).

Methods: Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) evaluation and CVR assessment using breath-holding index (BHI). Patients with impaired BHI (<0.69) were further evaluated with acetazolamide-challenged 99Tc-HMPAO-SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. TCD and SPECT were repeated in all patients at 4±1 months and they were followed-up for cerebral ischemic events.

Results: Of the 126 patients (80 male, mean age 56yrs; range 23-78yrs) that fulfilled our inclusion criteria, 84 (67%) showed impaired CVR HMPAO-SPECT. Fifty (60%) of them underwent STA-MCA bypass while 34(40%) received best medical treatment. TCD and acetazolamide-challenged HMPAO-SPECT repeated 4±1 months after surgery showed significant improvement in STA-MCA bypass group. TCD BHI improved from a median (IQR) of -0.05 to 1.1 (p<0.001). Compared to 98% patients with impaired CVR on pre-operative SPECT, only 20% showed abnormal results on post-operative imaging (p<0.001). During follow-up (mean 35 months; range 8 to 49months), only 6/50 (12%) patients in bypass group developed cerebral ischemic events as compared to15/34 (44%) cases on medical therapy (absolute risk reduction 32%, p=0.006).

Conclusion: 99Tc-HMPAO SPECT with acetazolamide challenge is a reliable tool for the assessment of cerebral vasodilatory reserve in patients with severe steno-occlusive disease of intracranial ICA or MCA. STA-MCA bypass surgery in carefully selected patients results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

Internal cerebral vein asymmetry on follow-up brain computed tomography after intravenous thrombolysis in acute anterior circulation ischemic stroke is associated with poor outcome

BACKGROUND

Identifying early predictors of functional outcome after acute ischemic stroke (AIS) is important for planning rehabilitation strategies. Internal cerebral veins (ICV) drain deep parts of brain, run parallel to each other, and consistently seen on computed tomography angiography (CTA). Even minor asymmetry in their filling can be identified. We hypothesized that venous drainage would be impaired in patients with acute occlusion of internal carotid artery or middle cerebral artery. Because systemic thrombolysis can alter the vascular findings, we evaluated the relationship between ICV asymmetry on follow-up CTA and functional outcome.

METHODS

Consecutive AIS patients treated with intravenous thrombolysis between 2007 and 2010 were included. ICV asymmetry was assessed by 2 independent blinded stroke neurologists/neuroradiologists. Functional outcome was assessed by the modified Rankin Scale (mRS) at 3 months, dichotomized as good (0-1) and poor (2-6). Data were analyzed for predictors of functional outcome.

RESULTS

Of 2238 patients with AIS, 226 (10.1%) anterior circulation AIS patients received intravenous thrombolysis. The median age was 65 years (range 19-92), 44% were men, and median National Institutes of Health Stroke Scale (NIHSS) score was 16 points (range 4-32). Hypertension was the commonest risk factor in 173 (76.5%) patients, whereas 78 (34.5%) had atrial fibrillation. ICV asymmetry on follow-up CTA was assessed in 103 (45.5%) patients. Admission NIHSS score (odds ratio [OR] 1.07; 95% confidence interval [CI] 1.079-1.201, P = .046), change in NIHSS score during first 24 hours (OR .737; 95% CI .672-.807, P < .0001), and ICV asymmetry on follow-up CTA (OR 20.3; 95% CI 4.67-52.07, P < .0001) independently predicted poor outcome at 3 months.

CONCLUSIONS

ICV asymmetry on follow-up CTA after intravenous thrombolysis is an early predictor of poor functional outcome.

Early and continuous neurologic improvements after intravenous thrombolysis are strong predictors of favorable long-term outcomes in acute ischemic stroke

BACKGROUND

Intravenously administered tissue plasminogen activator (IV tPA) remains the only approved therapeutic agent for arterial recanalization in acute ischemic stroke (AIS). Considerable proportion of AIS patients demonstrate changes in their neurologic status within the first 24 hours of intravenous thrombolysis with IV tPA. However, there are little available data on the course of clinical recovery in subacute 2- to 24-hour window and its impact. We evaluated whether neurologic improvement at 2 and 24 hours after IV tPA bolus can predict functional outcomes in AIS patients at 3 months.

METHODS

Data for consecutive AIS patients treated with IV tPA within 4.5 hours of symptom onset during 2007-2011 were prospectively entered in our thrombolyzed registry. National Institutes of Health Stroke Scale (NIHSS) scores were recorded before IV tPA bolus, at 2 and 24 hours. Early neurologic improvement (ENI) at 2 hours was defined as a reduction in NIHSS score by 10 or more points from baseline or an absolute score of 4 or less points at 2 hours. Continuous neurologic improvement (CNI) was defined as a reduction of NIHSS score by 8 or more points between 2 and 24 hours or an absolute score of 4 or less points at 24 hours. Favorable functional outcomes at 3 months were determined by modified Rankin Scale (mRS) score of 0-1.

RESULTS

Of 2460 AIS patients admitted during the study period, 263 (10.7%) received IV tPA within the time window; median age was 64 years (range 19-92), with 63.9% being men, a median NIHSS score of 17 points (range 5-35), and a median onset-to-treatment time of 145 minutes (range 57-270). Overall, 130 (49.4%) thrombolyzed patients achieved an mRS score of 0-1 at 3 months. The female gender, age, and baseline NIHSS score were found to be significantly associated with CNI on univariate analysis. On multivariate analysis, NIHSS score at onset and female gender (odds ratio [OR]: 2.218, 95% confidence interval [CI]: 1.140-4.285; P=.024) were found to be independent predictors of CNI. Factors associated with favorable outcomes at 3 months on univariate analysis were younger age, female gender, hypertension, NIHSS score at onset, recanalization on transcranial Doppler (TCD) monitoring or repeat computed tomography (CT) angiography, ENI at 2 hours, and CNI. On multivariate analysis, NIHSS score at onset (OR per 1-point increase: .835, 95% CI: .751-.929, P<.001), 2-hour TCD recanalization (OR: 3.048, 95% CI: 1.537-6.046; P=.001), 24-hour CT angiographic recanalization (OR: 4.329, 95% CI: 2.382-9.974; P=.001), ENI at 2 hours (OR: 2.536, 95% CI: 1.321-5.102; P=.004), and CNI (OR: 7.253, 95% CI: 3.682-15.115; P<.001) were independent predictors of favorable outcomes at 3 months.

CONCLUSIONS

Women are twice as likely to have CNI from the 2- to 24-hour period after IV tPA. ENI and CNI within the first 24 hours are strong predictors of favorable functional outcomes in thrombolyzed AIS patients.

Cerebral Hyperperfusion Syndrome After Superficial Temporal Artery-middle Cerebral Artery Bypass for Severe Intracranial Steno-occlusive Disease: A Case Control Study

BACKGROUND:

Intracranial stenoses carry increased risk for cerebral ischemia. We perform external carotid-internal carotid (EC-IC) artery bypass in our patients with severe stenosis of the intracranial internal carotid (ICA) or middle cerebral artery (MCA) with impaired cerebral vasodilatory reserve (CVR).

OBJECTIVE:

To evaluate cerebral hemodynamics and cerebral hyperperfusion syndrome (HPS) in patients who develop focal neurological deficits after EC-IC bypass surgery.

METHODS:

Patients with severe intracranial ICA or MCA stenosis and impaired CVR on transcranial Doppler (TCD) derived breath-holding index (BHI) were evaluated with acetazolamide-challenged technetium-99m hexamethylpropyleneamineoxime–single-photon emission computed tomography (SPECT). EC-IC bypass surgery was offered to patients with impaired CVR on SPECT. Close monitoring was performed in patients developing focal neurological deficits within 7 days of surgery.

RESULTS:

Of 112 patients with severe intracranial ICA/MCA stenosis, 77 (69%) showed impaired CVR and 46 (41%) underwent EC-IC bypass. Transient neurological deficits within 7 days of surgery developed in 8 (17%). HPS was confirmed by CT perfusion and/or SPECT in 7 cases. A strong correlation was observed between HPS and preoperative TCD-BHI values (0%, 6.3%, and 41% in patients with BHI 0.3-0.69, 0-0.3 and &lt;0, respectively; P = .012). HPS patients showed more than a 50% increase in MCA flow velocity on TCD (compared with preoperative values) on the operated side (63.3% vs 3.3% on control side, P &lt; .001). Meticulous control of blood pressure and hydration led to rapid and complete resolution of neurological deficits in all cases.

CONCLUSION:

Symptomatic cerebral HPS is common in the early postoperative period after EC-IC bypass surgery. Early diagnosis and appropriate management might prevent the complications of this syndrome.

Persistence of hyperdense middle cerebral artery sign on follow-up CT scan after intravenous thrombolysis is associated with poor outcome

BACKGROUND

The rates and extent of recovery in acute ischemic stroke (AIS) patients treated with intravenous tissue plasminogen activator (IV-tPA) remain highly variable. Hyperdense middle cerebral artery sign (HMCAS) on pretreatment unenhanced computerized tomography (CT) of the brain represents the presence of thrombus, often associated with severe neurological deficits and poor clinical outcome at 3 months. However, HMCAS is reliable only in AIS patients managed conservatively. In patients treated with systemic thrombolysis, HMCAS may disappear (representing clot dissolution) or persist (persisting clot) on the follow-up CT scan of the brain. We aimed at evaluating whether disappearance or the persistence of HMCAS on follow-up CT scan of the brain can predict the final outcome at 3 months.

METHODS

Data from consecutive AIS patients treated with IV-tPA, in a standardized protocol, from January 2007 to March 2010 were included in the prospective thrombolysis registry at our tertiary care center. For this evaluation, posterior circulation stroke was excluded. HMCAS was assessed on admission as well as follow-up CT by 2 independent stroke neurologists, blinded to the patient data or outcomes. Functional outcomes assessed by the modified Rankin Scale (mRS) at 3 months were dichotomized as good (mRS score 0-1) and poor (mRS score 2-6). The data were analyzed for the early predictors of poor functional outcome with SPSS version 19 for Windows.

RESULTS

Of the total of 2,238 patients admitted during the study period, 226 (11%) with anterior circulation AIS treated with intravenous thrombolysis were included. Median age of the patients was 65 years (range 19-92), 63% were males and they had a median National Institutes of Health Stroke Scale (NIHSS) score of 16 points (range 4-32). HMCAS was observed on admission CT scan in 109 (48.2%) patients and persisted on follow-up CT in 52 (47.7%) of them. Overall, 108 (47.8%) patients achieved poor functional outcome at 3 months. Admission NIHSS score (OR per 1-point increase = 1.241; 95% CI = 1.151-1.337, p < 0.0005), lesser change in NIHSS score at 24 h (OR per 1-point reduction = 0.730; 95% CI = 0.666-0.800, p < 0.0005) and persistence of HMCAS on follow-up CT scan (OR = 3.352; 95% CI = 1.991-11.333, p = 0.039) were associated with poor outcome at 3 months.

CONCLUSION

Persistence of HMCAS on the follow-up CT scan of the brain in acute ischemic stroke patients treated with IV-tPA can be used as an early predictor of poor functional outcome.

Abstract 3286: Persistently Reduced Venous Drainage After Intravenous Thrombolysis is Associated With Poor outcome in Acute Anterior Circulation Ischemic Stroke

Background- Significant numbers of acute ischemic stroke (AIS) patients recover with timely-administered intravenous tissue plasminogen activator (IV-TPA). However, rates and extent of recovery remain variable. Considering scarce and costly resources, early identification of reliable predictors for functional outcomes is important for planning rehabilitation strategies. We hypothesized that venous drainage would be impaired on the side of cerebral hypoperfusion due to acute occlusion of internal carotid or middle cerebral artery. The 2 internal cerebral veins (ICV) drain the deep parts of hemispheres and run backward to form great cerebral vein. Since ICVs are consistently seen on CT angiography (CTA), parallel and run very close to each other, even minor asymmetry in their filling can be easily diagnosed. ICV asymmetry in pre-TPA CTA can change in patients achieving arterial recanalization, rendering it less useful for predicting the long-term outcomes. Thus, we aimed at evaluating whether the presence of ICV asymmetry on follow-up CTA can predict the final outcome.

Methods- Data from consecutive AIS patients treated with IV-TPA, in a standardized protocol, from Jan2007 to March2010 were included in a prospective registry at our tertiary center. In this study, we excluded posterior circulation strokes. Significant proportion AIS patients undergo CTA on day 2 after IV-TPA to assess the status of arterial patency. ICV asymmetry was assessed by 2 independent stroke neurologists/ neuroradiologists, blinded to patient data or outcomes. Functional outcomes were assessed by modified Rankin Scale (mRS) at 3-months, dichotomized as good outcome (mRS 0-1) and poor outcome (mRS 2-6). Data were analyzed for the early predictors of function outcome.

Results- Of the total of 2238 patients admitted during the study period, 226 (10.1%) with anterior circulation AIS treated with intravenous thrombolysis were included. Median age was 65yrs (range 19-92), 63% males and median National Institute of Health Stroke Scale (NIHSS) 16points (range 4-32). Hypertension was the commonest vascular risk factor in 144 (76%) while 63 (33%) patients suffered from atrial fibrillation (AF). Overall, 108 (47.8%) patients achieved poor functional outcome at 3-months. ICV asymmetry could be assessed only in 103 (45.5%) patients on their follow up CTA films. Admission NIHSS score (OR1.08;95%CI 1.001-1.157,p=0.048) and ICV asymmetry on follow-up CT scan (OR 23.9;95%CI 5.15-63.99,p <0.0001) were associated with poor outcome at 3-months.

Conclusion- Presence of the asymmetry of internal cerebral veins on the follow up CT angiography in acute ischemic stroke patients treated with IV-TPA can be used as an early predictor of poor functional outcome.

Abstract 3267: Persistence of Hyperdense Middle Cerebral Artery Sign on Follow-up CT Scan is Associated with Poor Outcome in Ischemic Stroke Patients Treated with Intravenous Thrombolysis

Background- Early identification of reliable predictors of functional outcomes is important for planning rehabilitation strategies in patients with acute ischemic stroke (AIS). Hyperdense middle cerebral artery sign (HMCAS) on unenhanced computerized tomography (CT) of the brain represents presence of thrombus, often associated with poor outcome at 3-months. In thrombolyzed cases, HMCAS may disappear or persist on the follow-up CT scan. We evaluated whether persistence of HMCAS on follow-up CT predicts functional outcome at 3-months.

Methods- Consecutive AIS patients treated with intravenous thrombolysis between 2007 and 2010 were included. HMCAS was assessed on admission as well as follow-up CT by 2 independent readers, blinded to patient data and outcomes. Data were analyzed for early predictors of poor functional outcome at 3months (modified Rankin scale 2-6points).

Results- Of the total of 2238 patients admitted during the study period, 226 (10.1%) with anterior circulation AIS treated with intravenous thrombolysis were included. Median age of the IV-TPA treated patients was 65yrs (range 19-92), 63% males and median National Institute of Health Stroke Scale (NIHSS) 16points (range 4-32). HMCAS was observed on admission CT scan in 109 (48.2%) patients and persisted on follow-up CT in 52 (47.7%) of them. Overall, 108 (47.8%) patients achieved poor functional outcome at 3-months. Older age (OR 1.024;95%CI0.999-1.048), admission NIHSS score (OR1.08;95%CI 1.03-1.14,p=0.002) and HMCAS on follow-up CT scan (OR 10.25;95%CI 4.05-25.99,p <0.0001) were associated with poor outcome at 3-months.

Conclusion- Persistence of HMCAS on the follow up CT scan in AIS patients receiving intravenous thrombolysis is an early predictor of poor functional outcome at 3-months.

Extraction of brain tumor from MR images using one-class support vector machine

A novel image segmentation approach by exploring one-class support vector machine (SVM) has been developed for the extraction of brain tumor from magnetic resonance (MR) images. Based on one-class SVM, the proposed method has the ability of learning the nonlinear distribution of the image data without prior knowledge, via the automatic procedure of SVM parameters training and an implicit learning kernel. After the learning process, the segmentation task is performed. The proposed technique is applied to 24 clinical MR images of brain tumor for both visual and quantitative evaluations. Experimental results suggest that the proposed query-based approach provides an effective and promising method for brain tumor extraction from MR images with high accuracy.

Temporal lobe changes following radiation therapy: imaging and proton MR spectroscopic findings

Radiation therapy for nasopharyngeal carcinoma affects the temporal lobes. This paper characterizes proton MR spectroscopic findings of the temporal lobes and correlates them with imaging changes. Single-voxel proton MR spectroscopic examinations were acquired from 13 healthy adult volunteers (25 spectra) and 18 patients (28 spectra). All patients had biopsy-confirmed nasopharyngeal carcinoma and were previously treated with radiation therapy. Six patients (33%) had a single treatment and 12 (67%) patients had two treatments. Point resolved spectroscopy (PRESS) method was used (TR = 3,000 ms, TE = 135 ms) and data processed automatically using the LCModel software package for metabolite quantification. Voxel size and geometry were adapted to the lesion to reduce skull-base lipid contamination. The metabolites were quantitated relative to water signal. For each location, an additional non-water-suppressed reference scan in fully relaxed conditions was performed. The imaging findings were divided into four categories: I, normal; II, edema only; III, contrast-enhancing lesions; and IV, cystic encephalomalacia. The N-acetyl-aspartate levels were reduced in 27 (96%) spectra. Choline was increased in 3 (11%), normal in 4 (14%), and reduced in 21 (75%) spectra. The creatine level was normal in 8 (29%) spectra and reduced in 20 (71%) spectra. Imaging showed 4 (14%) spectra with category-I imaging findings; 5 (18%) spectra with category-II findings; 15 (54%) spectra with category-III findings; and 4 (14%) spectra with category-IV findings. Magnetic resonance spectroscopy showed reduced N-acetyl-aspartate in radiation-induced temporal lobe changes. Creatine levels were relatively more stable. Choline levels may be increased, normal, or reduced. Imaging findings ranged from normal to contrast-enhancing lesions and cystic encephalomalacia.

Cerebellopontine angle involvement by nasopharyngeal carcinoma

OBJECTIVE

This article describes a series of patients with nasopharyngeal carcinoma involvement of the cerebellopontine angle and discusses the clinical significance of this entity.

SETTING

Tertiary referral center.

STUDY DESIGN

Retrospective case study.

PATIENTS

Patients who were diagnosed with nasopharyngeal carcinoma with clinical features of cerebellopontine involvement by tumor.

INTERVENTIONS

Cerebellopontine involvement by tumor confirmed by computed tomography, magnetic resonance imaging, or both.

RESULTS

Patients with this entity either had advanced disease or had been treated previously for advanced nasopharyngeal carcinoma. They had varied clinical features attributable to cerebellopontine involvement, such as sensorineural deafness, dizziness, facial palsy, and facial numbness.

CONCLUSIONS

Cerebellopontine angle involvement by nasopharyngeal carcinoma is a difficult entity, both from the diagnostic and therapeutic points of view. In high-risk patients, particularly in patients who were previously treated for advanced nasopharyngeal carcinoma, a high index of suspicion for nasopharyngeal carcinoma involvement of the cerebellopontine angle is warranted when they experience unexplained neurootologic symptoms such as sensorineural hearing loss, dizziness and facial palsy.

Radiology of the retropharyngeal space

The retropharyngeal space extends from the skull base to the T4 vertebral level and contains the retropharyngeal nodes superiorly and fatty tissue elsewhere. This space is important as it is a potential route for the spread of infection and malignancy. This pictorial essay outlines the anatomy of the retropharyngeal space and illustrates the various disease processes that may be seen in region.Chong, V. F. H., Fan, Y. F. (2000). Clinical Radiology55, 740-748.

Radiation-induced temporal lobe changes: CT and MR imaging characteristics

OBJECTIVE

This article documents the CT and MR imaging characteristics of patients with temporal lobe changes after radiation therapy for nasopharyngeal carcinoma. These characteristics may serve to differentiate radiation-induced changes from intracranial tumor recurrence.

MATERIALS AND METHODS

We reviewed the imaging records of 1916 patients with nasopharyngeal carcinoma examined over a 5-year period. Forty-seven patients (2.5%) had temporal lobe changes. Thirty-four patients underwent CT (55 examinations), and 26 patients underwent MR imaging (32 examinations). Thirteen patients underwent CT and MR imaging. These studies were independently analyzed according to imaging technique and were categorized as follows: location of lesions, characteristics of gray or white matter changes, and patterns of late changes.

RESULTS

On CT, 12 patients (35%) had unilateral temporal lobe changes, and 22 patients (65%) had bilateral temporal lobe changes. The following patterns were noted: ill-defined contrast enhancement in 27 patients (79%); solid enhancement in six patients (18%); and ring enhancement in one patient (3%). On MR imaging, 11 patients (42%) had unilateral lesions, and 15 patients (58%) had bilateral lesions. Simultaneous gray and white matter lesions were noted in 17 patients (65%), and nine patients (35%) had lesions localized to the gray matter. Three patients (6%) had cerebral atrophy, and two patients (4%) had encephalomalacia.

CONCLUSION

The temporal lobes show characteristic CT and MR imaging features after radiation injury. Familiarity with these changes may assist in differentiating temporal lobe changes from progressive nasopharyngeal carcinoma.

Malignancy of the temporal bone and external auditory canal

A retrospective study of 18 patients with malignant tumors of the external auditory canal and temporal bone was undertaken to gain an Asian perspective of this rare disease. Of these patients, 15 (83%) had squamous cell carcinoma (SCC) and 61% had stage T3 tumors at presentation. The mean age was 56 years (range 38-82 years). Seven (39%) of the 18 patients had radiation-associated tumors (RATs), and all had undergone radiotherapy for treatment of nasopharyngeal carcinoma. The 1-year cumulative recurrence for the RAT group was 100%, but there was no recurrence in the non-RAT group (P = 0.001). In malignancies of the external auditory canal and temporal bone, a different classification and staging system for patients with RATs may be warranted to better guide treatment strategies.

Malignancy of the Temporal Bone and External Auditory Canal

A retrospective study of 18 patients with malignant tumors of the external auditory canal and temporal bone was undertaken to gain an Asian perspective of this rare disease. Of these patients, 15 (83%) had squamous cell carcinoma (SCC) and 61% had stage T3 tumors at presentation. The mean age was 56 years (range 38-82 years). Seven (39%) of the 18 patients had radiation-associated tumors (RATs), and all had undergone radiotherapy for treatment of nasopharyngeal carcinoma. The 1-year cumulative recurrence for the RAT group was 100%, but there was no recurrence in the non-RAT group ( P = 0.001). In malignancies of the external auditory canal and temporal bone, a different classification and staging system for patients with RATs may be warranted to better guide treatment strategies.

Facial lymphadenopathy in nasopharyngeal carcinoma

AIMS

This paper reports the findings of facial nodal metastasis in nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

The film records of 1916 patients with histologically confirmed NPC seen over a 5-year period were reviewed.

RESULTS

Eight facial nodes were demonstrated in three (0.2%) patients. There were three buccinator, two malar, two infraorbital and one mandibular nodes.

CONCLUSION

Facial nodal metastasis in NPC is unusual, but may be seen at presentation or during recurrence.

Imaging the sphenoid sinus: pictorial essay

This paper focuses on the spectrum of sphenoid sinus lesions that may be seen radiologically and the mapping of disease extent. Imaging plays a central role in the assessment of sphenoid sinus disease. Although primary sphenoid sinus disease is uncommon, this sinus is nevertheless affected secondarily by a variety of pathological processes.

Radiology of the nasopharynx: pictorial essay

The nasopharynx, located just below the central skull base, is a difficult area to evaluate clinically. Endoscopic examination provides useful information but cannot delineate submucosal disease. Benign lesions of the nasopharynx are relatively uncommon. They include Thornwaldt cyst, juvenile angiofibroma, haemangioma, haemangiopericytoma, Kimura's disease, branchial cleft cyst, oncocytoma, amyloidoma, and non-ossifying fibromyxoid tumours. The most common malignant lesions are carcinomas and lymphomas. Other malignant neoplasms such as adenocystic carcinomas are rarely seen. The purpose of the present pictorial review is to highlight the salient normal anatomy of the nasopharynx and the spectrum of pathological anatomy.

Meningeal infiltration in recurrent nasopharyngeal carcinoma

Permeative infiltration of the meninges appears to be a distinct form of recurrent nasopharyngeal carcinoma (NPC). The present report of eight patients with recurrent NPC illustrates meningeal infiltration following basal foramina extension. Seven of the eight patients (88%) showed jugular foramen involvement. Three patients had concomitant infiltration of the foramen magnum. There was one patient showing spread through the foramen lacerum. Only four (50%) of these patients had clinically detectable tumour in the nasopharynx, while the other half showed deep submucosal recurrence with endoscopically unremarkable findings. Permeative meningeal infiltration appears to be a distinct form of NPC recurrence. It is important to recognize this phenomenon so as to optimize the treatment options.

Nasopharyngeal carcinoma: review of how imaging affects staging

Imaging plays an important role in the staging of carcinoma of the nasopharynx. Accurate staging is necessary as the treatment is directly dependent on stage. Clinical examination provides information on mucosal involvement but is unable to determine the deep extension or presence of skull base invasion or intracranial spread. The 1997 International Union Against Cancer (UICC) and American Joint Committee on Cancer (AJCC) staging manuals were a collaborative project that provided a unified classification for nasopharyngeal carcinoma (NPC). The majority of staging can be identified only on imaging and not by clinical examination. The intent of this article is to provide information on the specific imaging findings that will directly affect the stage and treatment of NPC.

Magnetic resonance imaging of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor that shows distinct distributions into geographical and into well-defined high-risk ethnic groups. Radiation therapy is the mainstay of treatment, and imaging plays a central role in tumor mapping and post-treatment follow-up. Magnetic resonance imaging is better than computed tomography in demonstrating tumor extent, tumor recurrence, and postradiation complications. However, differentiating postradiation changes from tumor recurrence may be difficult using magnetic resonance imaging. Mucosal recurrence is best detected with endoscopy.

Temporal lobe necrosis following radiation therapy for nasopharyngeal carcinoma: 1H MR spectroscopic findings

PURPOSE

To observe the patterns of radiation-induced temporal lobe necrosis (TLN) following radiation therapy for nasopharyngeal carcinoma (NPC).

METHODS AND MATERIALS

Twenty-five proton magnetic resonance spectroscopic (1H MRS) examinations were acquired from 13 healthy adult volunteers for comparison with data from the patient population. There were 18 patients (28 spectra) with radiologic evidence of TLN and all patients were confirmed cases of NPC treated with radiation therapy. Six patients (33%) had a single treatment while 12 (67%) patients had two treatments. All 1H MRS examinations were performed on a 2-T whole body system (Bruker) using the point-resolved spectroscopy (PRESS) method with TE = 135 ms, TR = 3000 ms, and data processed automatically using the LCModel software package for metabolite quantification.

RESULTS

The N-acetyl-aspartate (NAA) levels were reduced in all except one spectrum (96%). Choline (Cho) was increased in 3 (11%), normal in 4 (14%), and reduced in 21 (75%) spectra. The creatine (Cr) level was normal in 8 (29%) spectra and reduced in 20 (71%) spectra. In four patients with normal imaging findings 1H MRS was abnormal.

CONCLUSION

1H MRS can characterize radiation-induced TLN. Spectra with increased Cho can be mistaken for neoplasm. Spectroscopy can also identify metabolic derangement before imaging.

Radiology of the orbital apex

The orbital apex, formed by the superior orbital fissure and optic canal, is the cross-road between the orbit and the intracranial structures. Pathological processes may extend intracranially via the superior orbital fissure and vice versa. In addition to intrinsic soft tissue lesions, various pathological processes may involve the surrounding osseous anatomy. Malignant lesions arising from adjacent structures or from haematogeneous metastasis may also infiltrate this region.

Parotid gland involvement in nasopharyngeal carcinoma

PURPOSE

This study documents the imaging findings of parotid gland involvement in nasopharyngeal carcinoma (NPC).

METHOD

This study reviewed the film records of 1,916 patients with NPC seen over a 5 year period. There were 27 (1.4%) patients with parotid involvement. There were 27 CT and 4 MR studies, and the pattern of involvement was categorized into the following groups: (1) parotid nodal involvement; (2) parotid invasion from extracapsular cervical nodal spread; (3) direct invasion by NPC; and (4) diffusely infiltrated gland not related to (2) or (3).

RESULTS

In the subset of 27 patients, parotid nodal involvement was seen in 11 (41%) patients. Ten (37%) patients had cervical extranodal spread into the parotid gland. Three patients (11%) showed direct invasion by NPC, and another three patients (11%) showed an isolated and diffusely infiltrated parotid gland.

CONCLUSION

Metastatic NPC may involve parotid nodes. The parotid gland may also be involved by extracapsular spread from enlarged cervical nodes or infiltrated directly by the primary lesion in the nasopharynx.

The suprahyoid neck: normal and pathological anatomy

The suprahyoid neck can be divided into fascia-bound spaces. These spaces, which are readily demonstrated on computed tomography (CT) and magnetic resonance imaging (MRI), form the anatomical framework for generating differential diagnosis and assessing disease extent. By correlating the radiological features with clinical information, the diagnostic possibilities of demonstrated lesions could be narrowed down considerably. Multiple space involvement is common in inflammatory and neoplastic processes and the full extent of these lesions should be outlined to facilitate surgical or radiotherapy planning.

Temporal bone tumours in patients irradiated for nasopharyngeal neoplasm

Radiation-associated tumours are rare complications of radiotherapy. This study seeks to highlight and discuss the clinically challenging problem of radiation-associated tumours (RATs) in the temporal bones of seven patients previously irradiated for nasopharyngeal neoplasm. Seven patients (six males and one female) with radiation-associated temporal bone tumours are presented (five squamous cell carcinomas, one osteogenic sarcoma and one chondrosarcoma). The initial nasopharyngeal disease for which radiotherapy was indicated was nasopharyngeal carcinoma (six patients) and nasopharyngeal lymphoma (one patient). The latency period between radiotherapy and presentation of temporal bone tumours ranged from five years to 30 years with a mean of 12.9 years. All the patients underwent surgical tumour resection. Three patients had post-operative radiotherapy and one patient underwent pre- and post-operative chemotherapy. Two patients died from the disease within three months of treatment with one patient surviving 36 months at the time of writing. One patient died from an unrelated medical condition three months after surgery. With refinement in radiotherapy techniques and the resultant increase in patient survival, there may be more patients with radiation-associated tumours in the future. It remains imperative for clinicians to be vigilant when patients previously irradiated for nasopharyngeal carcinoma present with otological symptoms as the key to the successful management of this condition lies in the early detection and expedient treatment of this difficult disease.

Pictorial review: radiology of the sphenoid bone

The sphenoid bone is located in the central skull base and forms part of the floor of the anterior and middle cranial fossae. The optic foramen, superior orbital fissure, foramen rotundum, foramen ovale and foramen spinosum are found within this complex bone. These foramina form important transition zones between intracranial and extracranial structures. Imaging plays a central role in delineating lesions within the sphenoid bone and the associated fissures and neural foramina. The purpose of this pictorial review is to highlight the pertinent normal and pathological anatomy of the sphenoid bone.

Carcinoma of the nasopharynx

Nasopharyngeal carcinoma (NPC) is an intriguing disease that shows a distinct geographical distribution with well-defined, high-risk ethnic groups. This neoplasm exhibits strong associations with the Epstein-Barr virus, dietary and genetic factors. Radiation therapy is the mainstay of treatment and imaging plays a central role in tumor mapping and radiation therapy planning. NPC provides an excellent model for the study of normal and pathological anatomy of the skull base. It also provides an excellent model in the study of consequences of radiation therapy.

Computed tomographic and magnetic resonance imaging findings in paranasal sinus involvement in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) may spread to the paranasal sinuses. This retrospective study describes the features of paranasal sinus involvement in NPC on computed tomography (CT) and magnetic resonance imaging (MRI). One hundred and fourteen patients with histologically proven NPC underwent staging with both CT and MRI. Maxillary sinus infiltration was demonstrated on MRI in 10 patients; sphenoid sinus infiltration in 24 patients; and, ethmoid sinus involvement in 4 patients. CT could separate inflammatory changes from tumour in all maxillary sinuses but is less helpful in the sphenoid and ethmoid sinuses. Contrast-enhanced MRI could differentiate tumour from inflammatory changes in all sinuses. Using MRI as the standard, the rates of CT separating tumour from inflammation are: maxillary sinus (100%), sphenoid sinus (43%) and ethmoid sinus (25%). Histological confirmation of tumour involvement in the paranasal sinuses is not available. It is important to separate sinusitis from tumour infiltration as prognosis and treatment planning may be affected.

Comparison of CT and MRI features in sinusitis

OBJECTIVE

To correlate the features of inflammatory changes in the paranasal sinuses on magnetic resonance imaging (MRI) with computed tomography (CT).

METHODS AND PATIENTS

One hundred and fourteen patients with histologically proven nasopharyngeal carcinoma (NPC) were staged with both CT and MRI. All CT and MRI images of patients with mucosal thickening but no tumour involvement of the sinuses were retrospectively analysed.

RESULTS

There were inflammatory changes in 36 maxillary, 21 sphenoid and 16 ethmoid sinuses. These changes include mucosal thickening, retention cysts, retained secretions, inspissated secretions and dystrophic calcification. MRI is superior to CT in separating thickened mucosa, retained secretions and retentions cysts.

CONCLUSION

It is important to appreciate CT changes of sinusitis and the corresponding spectrum of MRI features.

Functional endoscopic sinus surgery (FESS): what radiologists need to know

The place of coronal computed tomography (CT) in the assessment of patients prior to functional endoscopic sinus surgery (FESS) is well established. The ability to accurately correlate radiological and surgical anatomy enhances precision and safety during FESS. This pictorial essay reviews the conceptual anatomical framework that forms the basis of FESS.

Radiology of the parapharyngeal space

The parapharyngeal space (PPS) is a central space in the deep neck. Intrinsic lesions within this space are limited. Other spaces in the neck are closely related to the PPS and the direction of displacement of this space often suggests the origin of a lesion. The morphology of a lesion, together with the site of origin, helps in narrowing the diagnostic possibilities. The behaviour of the PPS often helps to determine whether a lesion is an intrinsic abnormality or whether it arises from a neighbouring space. Such information is crucial in the planning of surgical approach and the placement of drains.

Hypoglossal nerve palsy in nasopharyngeal carcinoma

The carotid space and the last four cranial nerves are at risk when nasopharyngeal carcinoma (NPC) recurs or spreads posterolaterally. The objective of this study is to document the features of hypoglossal nerve infiltration and the appearance of the paralysed tongue. We reviewed hypoglossal nerve palsy in 16 patients with NPC. The following features were analysed: tumour morphology (submucosal spread), hypoglossal canal erosion, perineural infiltration or intracranial spread, other lower cranial nerve palsies, and appearance of the tongue. These findings were correlated with clinical records. All 16 patients had tumour recurrence following radiation therapy. In 7 patients (44 %), recurrence was submucosal. Hypoglossal canal involvement was seen in 12 patients (75 %). Isolated hypoglossal nerve palsy was noted in 5 patients (31 %) and 7 patients (44 %) had posterior cranial fossa tumour spread. Posterior displacement of the tongue was consistently well seen. In conclusion, tumour recurrence should be suspected in the presence of hypoglossal nerve palsy even when endoscopic findings are negative. Posterior displacement of the tongue, which has not been emphasised in the literature, is an easily recognisable sign and may indicate early hypoglossal nerve palsy.

Radiology of the jugular foramen

The jugular foramen, a complex bony canal, transmits vessels and nerves from the posterior cranial fossa through the skull base into the carotid space. It is inaccessible to clinical examination and radiology plays a central role in evaluating this region. Familiarity with the normal anatomy of this area will help in the formulation of differential diagnosis and the assessment of disease extent. Both intracranial and extracranial lesions may affect the jugular foramen in addition to intrinsic abnormalities. Normal variants and artefacts seen on magnetic resonance imaging (MRI) should not be mistaken for pathological processes.

The retropharyngeal space: route of tumour spread

The retropharyngeal space is a potential route for the spread of infection and malignancy. We present patients with squamous cell carcinoma of the larynx and tongue with superior contiguous spread along the retropharyngeal space resulting in skull base erosion. The fascia defining the retropharyngeal space is attached to the skull base and pathological processes can extend superiorly to destroy the skull base.

Temporal lobe necrosis in nasopharyngeal carcinoma: pictorial essay

Nasopharyngeal carcinoma (NPC) shows a high frequency of skull base erosion and intracranial spread. This tumour is usually treated with radiation therapy. The medial and inferior portions of both temporal lobes are included within the radiation portals. These areas are therefore potential sites of radiation-induced necrosis. It is important to recognize this complication and separate it from intracranial tumour recurrence because the treatments of these entities are different.

Pedicular stress fracture in the lumbar spine

Spondylolisthesis with or without spondylolysis is common in the lumbar spine. Associated fracture in the pedicle ('pediculolysis') is unusual. The margins of pedicular stress fractures, like spondylolysis, usually appear sclerotic. A patient with a pedicular stress fracture with minimal marginal sclerosis suggesting an injury of recent onset is presented here. There was associated bilateral spondylolysis. The findings in this patient suggest that established pediculolysis probably represents a stress fracture that has failed to heal.

Pterygopalatine fossa and maxillary nerve infiltration in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) may infiltrate the pterygopalatine fossa (PPF) and the maxillary nerve. This study illustrates involvement of the maxillary nerve in the PPF with perineural spread to the cavernous sinus.

METHODS

One hundred and fourteen patients with proven NPC were studied using magnetic resonance imaging (MRI) and computed tomography (CT). The images were retrospectively reviewed for PPF infiltration and maxillary nerve involvement.

RESULTS

Seventeen (15%) patients showed infiltration of the PPF. Four patients had maxillary nerve involvement and a perineural spread to the cavernous sinus. Of the 17 patients with PPF infiltration, 8 (47%) patients showed hypoesthesia in the distribution of the infraorbital nerve. All 4 patients with contrast-enhancement of the maxillary nerve exhibited infraorbital neuropathy.

CONCLUSION

Infiltration of the maxillary nerve in the PPF with intracranial spread is uncommon but should be suspected in patients with infraorbital neuropathy. This is important as it affects both prognosis and radiation treatment planning.

Detection of recurrent nasopharyngeal carcinoma: MR imaging versus CT

PURPOSE

To compare the use of magnetic resonance (MR) imaging and computed tomography (CT) in detection of recurrent nasopharyngeal carcinoma.

MATERIALS AND METHODS

Forty-five sets of CT and MR images were obtained in 34 patients. The images were placed in three categories: (a) clinically or radiologically abnormal findings in patients who underwent biopsy (n = 16), (b) clinically normal and radiologically borderline findings in patients who were followed up clinically and radiologically (n = 10), and (c) clinically and radiologically normal findings in patients who were monitored only clinically (n = 19). All images were read by two observers independently.

RESULTS

There were nine positive and seven negative biopsy results. All patients in the latter two categories had normal findings at followup. CT had a sensitivity of 45% and 67% and a specificity of 64% and 70% for each of the two observers. MR imaging had a sensitivity of 56% (for both observers) and a specificity of 78% and 83%. The kappa test for interobserver concordance was 0.53 for CT and 0.66 for MR imaging.

CONCLUSION

Both modalities have relatively low sensitivity and moderate specificity in detection of tumor recurrence and in distinguishing recurrence from post-radiation therapy changes.