Dose measurement on both patients and operators during neurointerventional procedures using photoluminescence glass dosimeters.

BACKGROUND AND PURPOSE: Although radiation skin injuries associated with interventional radiology have been known as a critical issue, there are few reports mentioning direct measurement of the entrance skin dose (ESD). Thus, the purpose of this study was to clarify the regional distributions of ESDs in neurointervention. MATERIALS AND METHODS: Using photoluminescence glass dosimeters (PLDs), we measured the ESDs in 32 patients with a median age of 61.5 years. Angiographic parameters, including exposure time, dose-area product (DAP), and the number of digital subtraction angiography (DSA) studies and frames, were recorded. The ESDs of operators were analyzed by the same method. RESULTS: The maximum ESD of 28 therapeutic procedures was 1.8 +/- 1.3 Gy. Although the averaged ESD on the right temporo-occipital region was higher than that in other regions, disease-specific patterns were not observed. Statistically positive correlations were found between the maximum ESD and exposure time (r = 0.5283, P = .005), DAP (r = 0.7917, P < .001), the number of DSA studies (r = 0.5636, P = .002), and the number of DSA frames (r = 0.8583, P < .001). As for operators, ESDs to the left upper extremity were significantly higher than those to other regions. However, most of the ESDs were <0.2 mGy. Lead protective garments reduced the exposure doses to approximately one half to one tenth. CONCLUSION: It was shown that the regional ESD could be measured by applying the PLD. This method should contribute to reducing the dose accumulation in patients as well as in operators.

Patient skin dose during neuroembolization by multiple-point measurement using a radiosensitive indicator.

BACKGROUND AND PURPOSE: Although neuroembolization has recently spread quickly, sufficient attention has not been focused on the associated radiation exposure. The purpose of this research was to evaluate the patient's entrance skin dose (ESD) during neuroembolizations in 6 institutions. MATERIALS AND METHODS: This study was approved by all of the 6 institutional review boards, and all of the patients gave informed consent. This study included a total of 103 consecutive neuroembolizations in the 6 institutions. Patient ESDs during the procedures were evaluated by using caps that had 44 radiosensitive indicators adherent to the surface. The patient ESDs were calculated from the color difference of the indicators. To check for effects on the scalp, clinical follow-up was performed at 1-2 days, 2 weeks, and 3 months after the procedure. RESULTS: The averages of total fluoroscopic time, total number of digital subtraction angiography frames, and dose area product were 67.1 +/- 41.6 minutes, 883 +/- 626, and 257 +/- 150 Gy x cm(2), respectively. The average maximum ESD for each patient was 1.9 +/- 1.1 Gy (range, 0.4-5.6 Gy; median, 1.5 Gy). The average maximum ESDs of each institution ranged from 1.0 to 2.4 Gy. Epilation was observed in 6 patients. CONCLUSIONS: The maximum ESDs during neuroembolizations exceed the thresholds for radiation skin injuries in some cases.

Asymptomatic hypoesthesia of the maxillary alveolar ridge in complete denture wearers.

This study was carried out to investigate the effect of compression induced by complete dentures on the function of the nerves underlying the dentures. The influence of compression induced by complete dentures on nerve function was analysed using current perception threshold (CPT) in 33 complete denture wearers aged 50-80 at Nihon University School of Dentistry (Matsudo, Japan). Based on the age range of the complete denture group, dentate subjects were selected as a control. Because the group characteristics (such as subject age, gender, body mass index) and oral mucosal thickness were not matched, a multiple regression analysis was used to adjust for the influence of heterogeneous characteristics on the CPT. Statistically significant differences were found between subject groups for the nasopalatine and the greater palatine nerve. The results of the study were that complete denture wearers experience asymptomatic hypoesthesia mainly affecting the nasopalatine and greater palatine nerves, but not the infraorbital nerve.

Percutaneous transluminal angioplasty for atherosclerotic stenoses of intracranial vessels.

SUMMARY: To study the efficacy and long-term outcome of percutaneous transluminal angioplasty (PTA) with/without stent placement for intracranial atherosclerotic stenoses, we reviewed our treated cases retrospectively. Between May 1992 and October 2003, PTA with/without stents was performed in 64 intracranial and skull base vessels in 62 patients, including 24 middle cerebral arteries, 16 internal carotid arteries, 13 vertebral arteries, and 11 basilar arteries. PTA was technically successful in 55 vessels (86%). However, four vessels (6%) failed to achieve satisfactory dilatation. We encountered five periprocedural strokes as symptomatic complications, for a mortality rate of 4.7% and a morbidity rate of 3.1%. All the patients with stent placements survived angioplasty without any complication. In the clinical follow-up available for one week to 11.5 years (mean, 4.7 years), there were three strokes related to the treated vessels. The annual stroke rate in the affected territory was estimated at 1.2% per year. According to these results, PTA for intracranial atherosclerotic stenoses seems to be a beneficial therapy for immediate anatomical results and long-term stroke prevention. Stent-assisted PTA could help patients achieve successful dilatation and avoid complications.

Stenting for atherosclerotic stenosis of the intracranial or skull base cerebral arteries. Effectiveness and problems.

SUMMARY: Since May 1992, we have performed percutaneous transluminal angioplasty (PTA) or stenting 70 times for 65 lesions in 62 patients with atherosclerotic stenosis of the intracranial or skull base cerebral arteries. Stenting was carried out nine times for nine lesions in nine cases. Stenting was performed on patients with an average age of 62. The patients were eight men and one woman. The stenotic lesions involved the internal carotid artery (petrous portion) in four cases, the internal carotid artery (cavernous portion) in two cases, the internal carotid artery (supraclinoid portion) in one case, the middle cerebral artery (M1) in one case, and the vertebral artery (V4) in one case. The degree of stenosis ranged from 70% to 99%, with a mean of 80%. A stent for coronary arteries was used in all cases. After PTA was carried out in four cases, their initial extension was inadequate, and dissection was performed in five cases after PTA. As for the results of the treatment, subarachnoid haemorrhage occurred in one case due to perforation by the guidewire, and a major deficit was accepted. During the operation, asymptomatic cerebral infarction by distal embolism occurred in one case. Although obstruction of the lesion occurred three months after treatment in one case, symptoms did not appear. Stents used for atherosclerotic stenosis of the intracranial or skull base cerebral arteries still do not have sufficient performance. Although the stenting had problems, such as a prolonged patent, in the present condition, it was effective in terms of recovery from complications due to PTA.

Angiographical change of guglielmi detachable coils. Treated cerebral aneurysm in acute stage.

SUMMARY: Acute angiographical changes for preventing acute rebleeding on GDC treated cerebral aneurysms were evaluated. From December 2000 to November 2002, 48 total aneurysms in 44 consecutive patients with acute SAH. Acute angiographical evaluations were carried out in 46 aneurysms, including 42 ruptured and 4 unruptured aneurysms. Two cases were excluded because of poor medical condition. In this series, there were no rebleeding cases in acute stage. In the initial embolization for the 46 aneurysms, CO was achieved in eight aneurysms, NR in 15 aneurysms and BF in 23 aneurysms. Acute angiographical observations showed progressive thrombosis in 17 aneurysms (37%). No changes were observed in remaining 29. No recanalization was observed in this series. Only one case of BF, inside the aneurysm bleb was still observed during follow up. Additional embolization was carried out. Progressive thrombosis was frequently observed in GDC treated cerebral aneurysms during acute stage. This angiographical finding seems to show prevention of rebleeding, which is considered important for the management of GDC treatment in acutely ruptured cerebral aneurysm.

Retreatment of cerebral aneurysms after guglielmi detachable coil embolization.

SUMMARY: Of 175 patients with 181 aneurysms initially treated with Guglielmi Detachable Coils (GDC), 25 were retreated. All retreatments except one were performed on previously ruptured aneurysms. Thirteen aneurysms were retreated because of recurrence, and 12 aneurysms were retreated to complete initial insufficient embolization. Sixteen patients underwent re-embolization and 9 patients were operated upon surgically. No complications related to the retreatment were experienced. We consider that repeat embolization should be attempted before considering surgical treatment in case that additional therapy is required. However, it is difficult to retreat aneurysms having wide necks. In regard to surgical clipping, aneurysms without a coil in the neck are easier to treat with primary clipping, whereas aneurysms with a coil mass in the neck are difficult to surgical clip. We have never used temporary clipping and coil extraction if the distance between the coil and the parent artery was wider than 2 mm. Emerging new embolic agents or devices and technical improvement might decrease the need for retreatment and increase long-term efficacy after endovascular treatment.

Perfusion-weighted MRI of spinal dural arteriovenous fistula.

A 72-year-old woman was admitted with rapidly progressive paraplegia and sphincter disturbance. T2-weighted images of the thoracic spine showed intramedullary high signal with flow voids suggesting dilated medullary veins. Conventional spinal angiography demonstrated a dural arteriovenous fistula draining into perimedullary veins. Perfusion-weighted MRI demonstrated a prolonged mean transit time and increased blood volume in the high-signal area. The loss of normal perfusion gradient and venous hypertension and were thought to produce these differences. The time-to-peak was almost identical in the high-signal and isointense areas, although the bolus of contrast medium arrived earlier in the former. Arteriovenous shunting was thought to cause faster inflow. These changes may have resulted in increased blood volume in the spinal cord. The high signal has been attributed to oedema due to venous congestion, but there has been no histological confirmation. Perfusion MRI in this case supports this hypothesis.

Intraoperative angiography in the surgical treatment of cerebral arteriovenous malformations and fistulas.

BACKGROUND: The role of intraoperative angiography in the surgical treatment of cerebrovascular malformations remains controversial. The authors report on their experiences with intraoperative angiography in a series of 20 cases with cerebrovascular malformation to determine whether the use of intraoperative angiography has a favorable impact on the surgical treatment of cerebrovascular malformations. METHODS: Intraoperative angiography was performed in the surgical resection of arteriovenous malformation in 18 patients and in the surgical obliteration of arteriovenous fistula in 2 patients. The incidence of unexpected findings, such as residual nidus, demonstrated by intraoperative angiography was determined. FINDINGS: High-quality subtraction images were obtained by intraoperative angiography in every case and the findings prompted an additional procedure in 1 case that displayed an unexpected residual nidus (5.6%). There were no complications from the intraoperative angiography procedure. INTERPRETATION: Intraoperative assessment of technical results prior to wound closure offers the neurosurgeon the opportunity to resect or obliterate a vascular malformation completely, obviating a second operation.

Angiographic Follow-up of Embolization Using Guglielmi Detachable Coils for Cerebral Aneurysms.

SUMMARY: The purpose of this study is to evaluate the mid or long-term angiographical stability of Guglielmi Detachable Coils (GDC) after embolization for cerebral aneurysms. Between march 1997 and november 2001, 164 aneurysms, including 116 ruptured and 48 unruptured aneurysms, were treated using GDC at Mito National Hospital. Cerebral angiograms over one month after embolization were obtained in 111 aneurysms, including 71 ruptured and 40 unruptured aneurysms.At the time of initial GDC embolization of the 71 ruptured aneurysms, complete occlusion was achieved in 31 aneurysms, neck remnant in 18 aneurysms, and body filling in 22 aneurysms. Morphological changes were observed in 26 aneurysms (37%) in follow-up. Progressive thrombosis was obtained in 12 out of 71 aneurysms, no changes were shown in 45, and recanalizations occurred in 14. In the initial embolization of the 40 unruptured aneurysms, complete occlusion was achieved in 15 aneurysms, neck remnant in five and body filling in 20 aneurysms respectively. Morphological changes were observed in 12 aneurysms (30%), in which 12 aneurysms showed progressive thrombosis and 28 aneurysms were unchanged. There were significant differences of the longterm angiographical stability between ruptured and unruptured aneurysms. Rigorous follow-up angiography is mandatory when complete aneurysm occlusion is not achieved in ruptured aneurysms.

Dose measurement for patients and physicians using a glass dosemeter during endovascular treatment for brain disease.

It has been reported that exposure of patients and physicians to radiation from interventional radiological procedures cannot be disregarded. Direct measurement of patient exposure used to be difficult due to possible interference by the detector with the observation of X ray images. Recently, a dosemeter system consisting of small-sized glass chips and a reader which adopts pulsed UV laser stimulation has been developed. Owing to its small size, radiolucency and physical characteristics, direct monitoring of surface dose has become feasible. Dose measurement for patients and physicians during neurointervention was done using the photoluminescence glass dosemeter system. The dose-response of the dosemeter was almost linear over a broad dose range, but its energy dependency was rather high without a filter, the use of which is recommended by the manufacturer to compensate for energy dependency. Variation of sensitivity of about 20% was observed for effective energies of 45-60 keV which are used in neurointervention. In spite of this shortcoming, the photoluminescence glass dosemeter system was judged to be a convenient means for monitoring dose during neurointervention.

[Serial angiographical changes of a ruptured dissecting vertebral aneurysm].

A 54-year-old woman presented a subarachnoid hemorrhage from a ruptured dissecting aneurysm on the right vertebral artery. A right vertebral angiogram revealed a fusiform dilatation distal to the right posterior inferior cerebellar artery and "pseudo lumen" was observed in a delayed arterial phase. Conservative treatment was carried out, and the patient condition gradually improved. An angiographical examination for planned endovascular treatment 46 days after the onset, revealed the normalization of the formerly dilated caliber of the right vertebral artery with only a minor luminal irregularity. However, 83 days after the onset, right vertebral angiogram showed reappearance of the fusiform dilatation. The right vertebral angiogram obtained 204 days after the onset showed that the dilated segment of the dissecting aneurysm had become normalized to a slight degree. The serial angiographical changes of the dissecting site might have been due to regression and organization following transient thrombosis of intramural hematoma. Such drastic changes within a short period have not been reported yet. In conclusion, careful repeated follow-up is recommended in monitoring aneurysmal formation during the early to chronic phase after rupture of a dissecting aneurysm. The repetition of angiography is important, because later, if angiography has been performed only once, aneurysmal dilatation may be overlooked. One has to be aware of such changes, because such changes may alter the clinician's decision about treatment, as they did in our case.

Revascularization Using an Extracorporeal Pump for the Treatment of Cerebral Embolism in the Acute Stage. For Protection of the Brain Tissue from Irreversible Change due to Cerebral Embolism.

SUMMARY: Object. For patients with cerebral embolism, we are using an extracorporeal pump to rev ascularize the more peripheral brain tissues far from the thrombus, proceeding the microcatheter beyond the thrombus, and dissolving the thrombus during a satisfactory time as required. Methods. As the critical cerebral blood flow is thought to be below 30 mlllOOglmin, in the case of middle cerebral artery occlusion at the Ml portion, over 15mllmin. of arterial blood is necessary to protect the brain tissue from irreversible change. One thousand and eight hundred mmHg (about 2 atoms) of pump pressure is necessary to send l5mllmin. of blood through the microcatheter (110 cm, FastTrucker 18, Boston). It was confirmed by laboratory and clinical data that hemolysis of the pump action is not sufficient to aggravate kidney function. Conclusion. This method enables the protection of brain tissues from irreversible change after cerebral embolism, and extends the time sufficiently for thrombolysis.

The embolization of ruptured aneurysms in acute stage.

SUMMARY: We have treated 93 ruptured aneurysms with Guglielmi Detachable Coils (GDC) in acute period. Seventy-three patients (78%) were independent on discharge. Among the patient of Hunt and Hess Grade I, II and III, 59 patients (88%) were independent. Acute re-rupture occurred in two elderly patients with insufficient embolization and two patients experienced rerupture in the follow up period. Symptomatic vasospasm was reported in 17.6% of patients. The permanent morbidity rate is 4.4% and one patient died (1.5%). Although the long-term results remain to be determined, embolization with GDC is a safe and promising treatment for acutely ruptured aneurysms.

Rupture of Aneurysms during and after Embolization with Guglielmi Detachable Coils.

SUMMARY: Between March, 1997 and June, 2000, 104 aneurysms, including 75 ruptured and 29 unruptured aneurysms, were treated with Guglielmi detachable coils by 120 embolizations in our institution. Intraprocedual perforation occurred in four cases, representing 3.3% of the embolizations. Subsequently, two cases deteriorated, and the other two cases recovered completely without any deficit. Aneurysmal perforations mostly occurred in acutely ruptured aneurysms, small aneurysms less than 4 mm, anterior communicating artery aneurysms, or first coil delivery. Rebleedings in the acute period of subarachnoid hemorrhage occurred in four cases of partial occlusion due to aneurysmal morphology, such as a wide neck or an irregular shape. Rebleedings in the chronic period occurred in two cases, one of which rebled two months after partial occlusion, and the other of which rebled 27 months after nearly total occlusion. No subarachnoid hemorrhages documented from previously unruptured aneurysms occurred after embolizations. Insufficient embolization for ruptured aneurysms cannot prevent rebleeding, and partially occluded aneurysms and recurring aneurysms in the follow-up period require immediate re-treatment.