Chung-Jung Lin

Toward the Era of a One-Stop Imaging Service Using an Angiography Suite for Neurovascular Disorders

Transportation of patients requiring multiple diagnostic and imaging-guided therapeutic modalities is unavoidable in current radiological practice. This clinical scenario causes time delays and increased risk in the management of stroke and other neurovascular emergencies. Since the emergence of flat-detector technology in imaging practice in recent decades, studies have proven that flat-detector X-ray angiography in conjunction with contrast medium injection and specialized reconstruction algorithms can provide not only high-quality and high-resolution CT-like images but also functional information. This improvement in imaging technology allows quantitative assessment of intracranial hemodynamics and, subsequently in the same imaging session, provides treatment guidance for patients with neurovascular disorders by using only a flat-detector angiographic suite—a so-called one-stop quantitative imaging service (OSIS). In this paper, we review the recent developments in the field of flat-detector imaging and share our experience of applying this technology in neurovascular disorders such as acute ischemic stroke, cerebral aneurysm, and stenoocclusive carotid diseases.

Application of color-coded digital subtraction angiography in treatment of indirect carotid-cavernous fistulas: Initial experience

Background: Parametric‐colored digital subtraction angiography using Tmax is almost a routine angiographic imaging procedure, currently. The current feasibility study is aimed to using the imaging to monitor treatment effects while embolizing indirect carotid‐cavernous fistulas (CCF). Methods: Ten patients with CCFs receiving embolization and 40 patients with normal circulation time were recruited. Their color‐coded DSAs were used to define the Tmax of selected intravascular ROIs. A total of 19 ROIs in the internal carotid artery (ICA) (cervical segment of ICA in AP view (I0), cavernous segment of ICA in AP view (I1), supraclinoid segment of ICA in AP view (I2) and cervical segment of ICA in lateral view (I0′), cavernous portion of ICA in lateral view (IA), supraclinoid portion of ICA in lateral view (IB)), ACA (first segment of anterior cerebral artery, second segment of anterior cerebral artery (A1, A2)), middle cerebral vein (MCA) first segment of MCA ((M1), second segment of MCA (M2)), frontal vein (FV), parietal vein (PV), superior sagittal sinus (SSS), sigmoid sinus (SS), internal jugular vein (JV), fistula, superior ophthalmic vein (SOV), inferior petrosal vein (IPS), and MCV were selected. Relative Tmax was defined as the Tmax at selected ROIs minus Tmax at I0 or I0′. An intergroup comparison between the normal and treatment groups and pre‐ and post‐treatment comparison of the peri‐therapeutic rTmax for the treatment group were performed. Results: rTmaxs for the normal group were as follows: Anterior‐posterior view: I1: 0.16, I2: 0.32, A1: 0.31, M1: 0.35, SSS: 6.16, SS: 6.56, and MCV: 3.86 seconds. Lateral view: IA: 0.05, IB: 0.20, A2: 0.53, M2: 0.95, FV: 4.84, PV: 5.12, IPS: 4.62, JV: 6.81, and MCV: 3.86 seconds. Before embolization, rTmax of the IPS, SS, and JV for the treatment group were shortened (p < 0.05). No rTmaxs for any arterial ROIs in the fistula group were significantly different. After embolization, the rTmaxs for all venous ROIs returned to normal except for two which were partially obliterated. Conclusion: This postprocessing method does not require extra radiation exposure and contrast media. It facilitates real‐time hemodyamic monitoring and may help determining the endpoint of embolization, which increases patient safety.

Peritherapeutic quantitative flow analysis of arteriovenous malformation on digital subtraction angiography

BACKGROUND Digital subtraction angiography (DSA) provides detailed hemodynamic information. However, the imaging interpretation is mainly based on the physicians experience and observation. We aimed to quantitatively study the peritherapeutic blood flow changes of a cerebral arteriovenous malformation (AVM) treated by embolization using optical flow estimation on DSA. METHODS A 37-year-old woman with an AVM in the right frontal lobe of her brain was enrolled. The optical flow method with a pixel-by-pixel measurement was applied to determine the blood flow in brain vessels on anterior-posterior and lateral DSA views before and after embolization. RESULTS A return toward normalization of blood flow as a result of embolization was determined semiquantitatively on the posttherapeutic DSA. CONCLUSIONS Optical flow analysis on DSA illustrated the potential of quantifying intracranial blood flows in patients with cerebral vascular disorders and the therapeutic effects.

Endovascular Management of Post-Irradiated Carotid Blowout Syndrome

Purpose To retrospectively evaluate the clinical and technical factors related to the outcomes of endovascular management in patients with head-and-neck cancers associated with post-irradiated carotid blowout syndrome (PCBS). Materials and Methods Between 2000 and 2013, 96 patients with PCBS underwent endovascular management. The 40 patients with the pathological lesions located in the external carotid artery were classified as group 1 and were treated with embolization. The other 56 patients with the pathological lesions located in the trunk of the carotid artery were divided into 2 groups as follows: group 2A comprised the 38 patients treated with embolization, and group 2B comprised the 18 patients treated with stent-graft placement. Fisher’s exact test was used to examine endovascular methods, clinical severities, and postprocedural clinical diseases as predictors of outcomes. Results Technical success and immediate hemostasis were achieved in all patients. The results according to endovascular methods (group 1 vs 2A vs 2B) were as follows: technical complication (1/40[2.5%] vs 9/38[23.7%] vs 9/18[50.0%], P = 0.0001); rebleeding (14/40[35.0%] vs 5/38[13.2%] vs 7/18[38.9%]), P = 0.0435). The results according to clinical severity (acute vs ongoing PCBS) were as follows: technical complication (15/47[31.9%] vs 4/49[8.2%], P = 0.0035); rebleeding (18/47[38.3%] vs 8/49[16.3%], P = 0.0155). The results according to post-procedural clinical disease (regressive vs progressive change) were as follows: alive (14/21[66.7%] vs 8/75[10.7%], P<0.0001); survival time (34.1±30.6[0.3–110] vs 3.6±4.0[0.07–22] months, P<0.0001). Conclusion The outcomes of endovascular management of PCBS can be improved by taking embolization as a prior way of treatment, performing endovascular intervention in slight clinical severity and aggressive management of the post-procedural clinical disease.

Imaging quality and diagnostic reliability of low-dose computed tomography lumbar spine for evaluating patients with spinal disorders

BACKGROUND CONTEXT Computed tomography (CT) scans of the lumbar spine (CTLS) have demonstrated a higher level of accuracy than plain films and have been used to assess patients with spinal disorder when magnetic resonance imaging is not available. Nevertheless, radiation exposure remains a serious safety concern. Iterative reconstruction (IR) decreases the CT radiation dose for diagnostic imaging. However, the feasibility of using IR in CTLS is unclear. PURPOSE To evaluate the imaging quality and diagnostic reliability of CTLS with IR. STUDY DESIGN A prospective study. PATIENT SAMPLE All patients from outpatient departments who suffered from spinal disorders and were referred for CTLS. OUTCOME MEASURES In acquired CT images, the signal-to-noise ratio (SNR) of the dural sac (DS), intervertebral disc (IVD), psoas muscle (PM), and L5 vertebral body, the contrast-to-noise ratio between the DS and IVD (D-D CNR), and the subjective imaging qualities were compared across groups. Interobserver agreement was evaluated with kappa values. METHODS Patients receiving low radiation CTLS were divided into three groups. A 150 mAs tube current with 120 kVp tube voltage was used with Group A and a 230 mAs tube current with 100 kVp tube voltage with Group B. Intended end radiation exposure was 50% less than that of the control group. Tube modulation was active for all groups. The images of the two low-radiation groups were reconstructed by IR; those of the control group by filtered back-projection (FBP). RESULTS The SNRs of the DS, IVD, PM, BM, and D-D CNR of Group A were not inferior to those of the control group. All SNRs and D-D CNRs for Group B were inferior to those of the control group. Except for that of the facet joint, all subjective imaging ratings for anatomic regions were equivalent between Groups A and B. Interobserver agreement was highest for the control group (0.72-0.88), followed by Group A (0.69-0.83) and B (0.55-0.83). CONCLUSIONS Fifty percent tube current reduction combined with IR provides equivalent diagnostic accuracy and improved patient safety when compared with conventional CTLS. Our results support its use as a screening tool. With the tube modulation technique, further adjustments in weighting IR and FBP algorithms based on body mass index become unnecessary.

Intraprocedure aneurysm rupture in embolization: Clinical outcome with imaging correlation

Background: Intraprocedural aneurysm rupture (IPAR) is the most feared complication of embolization for intracranial aneurysms. Here we report the immediate and long‐term imaging outcomes of IPAR during embolization and the correlation with clinical outcomes. Methods: Of the 376 consecutive patients harboring 412 intracranial aneurysms who had underwent endovascular coil embolizations in the past 9 years, 10 patients (2.7% per patient, 2.4% per aneurysm) had IPAR. There were two men and eight women, with an age range of 40–71 years (mean: 52 years). Imaging findings, including immediate cerebral angiography, brain computed tomography (CT), and follow‐up CT, were analyzed. Final clinical patient outcome was evaluated by modified Rankin scale (mRS). Results: The causes of the IPARs were coil protrusion (n = 7), microcatheter perforation (n = 2), or they were spontaneous (n = 1). Nine cases involved previously ruptured aneurysms, while one was unruptured; aneurysmal location of the IPARs was the anterior (n = 5) or posterior (n = 4) communicating artery or the anterior cerebral artery (n = 1). Angiographic cerebral hemodynamic compromise was observed in four patients and associated with poor clinical outcomes. Immediate CT showed contrast media and/or intracranial hemorrhage expansion in all the patients. Cerebral tissue loss due to ischemia and/or hemorrhagic occurred in six patients with more than 3 months of follow‐up. On more than a 3‐month clinical outcome, six patients presented with good recoveries (mRS: ≤ 2). One patient exhibited a moderate disability (mRS: 4), and three patients died (mRS: 6). Conclusion: IPAR is an uncommon complication and usually occurs during the advancement of the coil into the aneurysm sac. Angiographic hemodynamics is an important indicator to determine the outcome of the IPAR. Brain CT demonstrates the progression of the IPAR and the cerebral tissue loss resulting from ischemic or hemorrhagic events.

Stent-assisted coil embolization of intracranial aneurysms: A single center experience

Background: Endovascular detachable coil embolization has become an important method in the management of intracranial aneurysms. However, coil embolization alone may fail to treat some wide‐neck aneurysms. Herein, we report our experience with and outcome of stent‐assisted coil embolization (SACE) of intracranial aneurysms. Methods: Over a 5‐year period, a total of 59 patients diagnosed with 63 intracranial aneurysms underwent SACE. Of the total 63 aneurysms, 6 aneurysms were treated by SACE as a salvageable procedure because of coil instability after detachment. There were 17 men and 42 women enrolled in the study, with ages ranging from 24 to 86 years (mean: 60 years). We retrospectively assessed the clinical data, aneurysm characteristics, and angiographic and clinical outcomes of all patient cases. Results: The mean aneurysm size was 9.4 mm, and the mean neck size was 5.5 mm. Clinical and angiographic follow‐up exceeding 6 months were available in 51 and 40 patients, respectively. The mean clinical follow‐up time was 28 months (range: 6–49 months). Successful stent deployment was found in 60 aneurysms (95%). Midterm total or subtotal angiographic aneurismal occlusion was obtained in 56 aneurysms (89%), with further thrombosis of the aneurismal sac occurring in 4 (10%). Stable coiling aneurysm was found in 24 (78%), aneurysm recurrence was observed in 5 (13%), and permanent procedural morbidity was observed in two patients (3.4%). During the follow‐up period, there were no hemorrhagic events and no stent displacement. Conclusion: Despite a modest procedural complication rate, and some evidence of aneurismal recurrence, SACE was proved to be both effective and safe in managing wide‐neck intracranial aneurysms. Our results also demonstrated the midterm durability and stability of aneurysm treated by SACE. Furthermore, SACE can be a salvageable procedure in cases with coil instability after detachment.

Transarterial detachable coil embolization of direct carotid-cavernous fistula: Immediate and long-term outcomes

Background: Transarterial embolization is a standard method for management of direct carotid‐cavernous fistula (DCCF). The purpose of this study was to report our experiences, and immediate and long‐term outcomes of endovascular embolization of DCCFs by using detachable coils (DCs). Methods: Over 8 years, 24 patients with 25 DCCFs underwent endovascular DC embolization. There were 15 men and nine women; age ranged from 8 to 82 years (mean, 39 years). Immediate and long‐term angiographic as well as clinical outcomes after endovascular DC embolization were retrospectively analyzed. The number and the length of DCs used to occlude the fistula were also evaluated. Results: Eighteen DCCFs were successfully occluded by single‐session endovascular embolization with preservation of the parent artery. Retreatments by transvenous (n = 5) and/ or transorbital routes (n = 3) had to be performed in seven patients because of residual fistula (n = 4) or recurrent fistula (n = 4) occurring within 3 weeks after embolization. The average numbers and length of coils to occlude the fistulas were 14 (range, 2–31) and 189 cm (range, 16–756 cm), respectively. Four patients had small residual fistulas with spontaneous thrombosis on follow‐up angiography. Three patients had transient cranial nerve impairment of the third (n = 1) or sixth (n = 2) nerve. There was no significant procedure‐related neurological complication. The follow‐up period was 3–48 months (mean, 19 months) Conclusion: Endovascular DC embolization of DCCFs was proved both efficacious and safe in managing high‐flow fistulas with sustained angiographic and clinical effects, particularly in those DCCFs with small fistula track and/or cavernous sinus. However, retreatment via various routes may be necessary in some patients because of residual or recurrent fistulas.

Transarterial Onyx embolization of intracranial dural arteriovenous fistulas: A single center experience

Background: Transarterial embolization of intracranial dural arteriovenous fistulas (DAVFs) is usually associated with inadequate embolization. The purpose of this study was to report our experience of transarterial Onyx embolization of intracranial DAVFs with an emphasis on treatment outcome with this new embolic agent in different types of DAVFs. Methods: In the past 3 years, a total of 14 intracranial DAVFs have been treated by transarterial Onyx embolization. Among these, there were nine males and five females, aged from 30 years to 82 years (mean = 62 years). We retrospectively analyzed the injection volume and time of Onyx embolization as well as outcomes in different types of DAVFs. Results: The locations of the DAVFs were sigmoid sinus (n = 6), tentorium (n = 3), sinus confluence (n = 2), transverse–sigmoid sinus (n = 1), sigmoid sinus–jugular bulb (n = 1) and the superior petrous sinus (n = 1). The mean volume and time of Onyx injection were 3.4 mL and 28 minutes, respectively (Cognard type I: 4.9 mL, 40 minutes; type II: 4.5 mL, 34 minutes; type III: 2.2 mL, 21 minutes; type IV: 2 mL, 22 minutes). Total fistula occlusion was achieved in six out of seven patients of type III and type IV DAVFs, and in four out of seven patients of type I and type II DAVFs. Nine patients had total resolution of their symptoms, whereas partial regression occurred in five patients. No significant periprocedural complication was found. Mean clinical follow‐up period was 16 months. Conclusion: Transarterial Onyx embolization of intracranial DAVFs is safe and effective. This technique is particularly useful in type III and type IV DAVFs with a high cure rate, and lower volume of Onyx as well as a short injection time.

Transarterial Embolization of Traumatic Carotid-cavernous Fistulae by Gugliemi Detachable Coils: A Seven-year Experience

We report our experience with transarterial embolization of traumatic carotid-cavernous fistulae (TCCFs) by using Gugliemi detachable coil (GDC). From 2000 to 2007 at our institution, 11 patients with 12 TCCFs underwent transarterial GDC embolization because of failure to occlude fistulae by detachable balloon with preservation of the parent artery. The cause of the failure to occlude the fistula by detachable balloon was small fistula tract (n=9) and/or tortuous parent artery (n=3) or repeated balloon puncture by bony fragment (n=1). All TCCFs were successfully occluded by a single session transarterial GDC embolization. The average number of coils were eight (range, two-16) with an average length of 104 cm (range, 12–283 cm). No statistically significant procedure-related neurological complication or recurrent TCCF was observed in any of the patients. Transarterial GDC embolization is a useful method in the treatment of TCCFs, particularly in those TCCFs with small fistula tract or small CS.