Blind image restoration algorithm based on improved sparse Bayesian low dose CT

Abstract

In China, moyamoya disease is one of the main causes of stroke events in children and adults. Early diagnosis and early treatment can prevent irreversible damage to nerve function and greatly improve the quality of life of patients. Based on the improved sparse Bayesian low-dose CT image blind restoration algorithm, moyamoya disease diagnosis and treatment has important application value guidance and evaluation Cheng, through the retrospective analysis of the clinical characteristics, imaging characteristics and treatment of 105 patients with moyamoya disease diagnosed by Blind image restoration algorithm based on improved sparse Bayesian low dose CT from April 2012 to November 2015 in a hospital in Hefei City, we think that CT angiography has important application value in the diagnosis and treatment of moyamoya disease, and we can draw a conclusion. Among these 105 patients, women are the majority. The ratio of male to female was 1:1.188, and the peak period was 30– 40 years old. There were 41 cases of ischemic stroke and 64 cases of hemorrhagic stroke. 29 patients underwent STA-MCA bypass, temporal muscle compression and dural reversal. Blind image restoration algorithm based on improved sparse Bayesian low dose CT was reexamined. The results of Blind image restoration algorithm based on improved sparse Bayesian low dose CT and DSA were the same. It can be seen that Blind image restoration algorithm based on improved sparse Bayesian low dose CT is a reliable method to diagnose moyamoya disease, which can be used as a preoperative guidance and postoperative evaluation of bypass vessel patency and collateral circulation formation.

Keywords

CT angiography moyamoya disease artery bypass

1 Introduction

Moyamoya disease, also known as abnormal vascular network of brain base, is a chronic progressive cerebrovascular occlusive disease with unknown etiology. The lesions mainly involved the ICA siphon of bilateral internal carotid artery and the proximal part of middle cerebral artery, resulting in chronic progressive stenosis or occlusion of the vascular lumen, which was related to the formation of the vascular network at the bottom of the brain. Moyamoya disease originated in Japan, the highest incidence in Japan. At present, there are more than 10000 patients. In recent years, the incidence of moyamoya disease in China has increased year by year [1]. According to incomplete statistics, there are more than 7000 patients with moyamoya disease in China, of whom women are biased. The prevalence of patients is more concentrated in adults. The initial symptom of adult moyamoya disease is cerebral hemorrhage. But the clinical symptoms of this disease are complex and varied, often accompanied by dizziness, mental decline, aphasia, etc... Therefore, it is often misdiagnosed as cerebral thrombosis or other mental disorders, which directly affects the treatment of the disease [2]. If patients don’t treat moyamoya disease in time, it may leave patients with different degrees of neurological dysfunction, and some even endanger their lives. In order to diagnose and treat moyamoya disease in time, there has been a consensus on the diagnosis method at home and abroad, which is to use multi-slice spiral CT angiography Technology [3].

With the updating of image detection equipment and the deepening of understanding of moyamoya disease, the number of people diagnosed with moyamoya disease is increasing. In clinical practice, blind image restoration algorithm based on improved sparse Bayesian low-dose CT has become an important method for diagnosis and treatment of moyamoya disease [4]. It can improve the diagnosis rate of moyamoya disease and the therapeutic effect of patients [5]. At the same time, through analysis, we can further study the pathological characteristics and pathogenesis of moyamoya disease, and provide theoretical basis for clinical diagnosis and treatment of moyamoya disease. Through the study on the diagnosis and treatment of 105 patients in a hospital in Hefei from April 2012 to November 2015, the application value and advantages of this method in the diagnosis and treatment of the disease were clarified. Therefore, it is of great significance to further promote the application of this method for the clinical diagnosis and treatment of this disease in China.

2 Disease and related imaging diagnosis

Moyamoya disease is a comparatively rare cerebral vascular disease with specific features, mainly characterized by progressive thickening of the ICA terminal intima and narrowing of the lumen. The occlusion or stenosis of MCA and ACA was further performed. Finally the traditional artery of skull base formed collateral circulation similar to the smog, which can realize the compensatory blood supply. The disease development of moyamoya disease is relatively slow, and in most cases it is occult disease, therefore, it is often with clear clinical symptoms. In this situation, it leaded to neurological dysfunction of cerebral vascular disease [6]. moyamoya disease occurs mostly in Southeast Asia region, represented by Japan. However, in recent years, there is a high incidence in the world. The pathogenesis of moyamoya disease is quite complex, and the possible causes might be thrombosis, infection, vasculitis, and early onset atherosclerosis, etc... In clinical manifestation, the common moyamoya disease is divided into two types: ischemic type and hemorrhagic type [7]. The lack of blood type can be specifically classified as cerebral infarction and transient cerebral ischemia. The blood type is particularly common among adult, Current studies suggest that intracranial hemorrhage is more common in hemorrhage stroke, including three kinds of cerebral hemorrhage, cerebral ventricles hemorrhage and subarachnoid hemorrhage [8].

There is no cure for the treatment of moyamoya disease. Vascular reconstruction is often used to avoid hemorrhage and ischemia, and this kind of operation is divided into two kinds of vascular reconstruction directly and indirectly. Direct reconstruction adopts direct anastomosis of the intracranial and extracranial vascular, The most commonly used is the superficial temporal artery and the same side of the middle cerebral artery anastomosis, Indirect vascular reconstruction includes EMS, EDAMS, EDAS and other methods [9]. Although revascularization operation can be taken to relieve the hemorrhage of moyamoya disease to a certain extent, In particular, the combination of direct and indirect revascularization procedures can be more effective in controlling the disease. In this way, more ideal therapeutic effect will be achieved if we develop the corresponding individual treatment plan according to different patients [10]. Meanwhile, based on imaging, in-depth study of the pathogenesis of moyamoya disease can be carried out to understand the pathological development of the disease. Eventually through the statistical analysis of a large number of cases, we can develop more effective treatment and preventive measures.

At present, the diagnosis of moyamoya disease usually focuses on the analysis of blood vessel imaging and blood flow attention. The “gold standard” for diagnosis is digital subtraction angiography (DSA), which can directly observe the degree of vascular stenosis as well as collateral circulation of compensatory blood supply [11] Even if dense regularity has not yet appeared in the smoke-like vascular network, it is still able to carry out a more clear display through the DSA. Using DSA to analyze the imaging characteristics of moyamoya disease we detect that patients actually form the formation and distribution of abnormal vascular network in patients with cerebral bottom, and the formation of collateral circulation, Part of the patients will have an aneurysm, which will affect the posterior cerebral artery or the basilar artery. The prolongation of the cerebral blood circulation can lead to the delay of the development of the vein and sinus. The conventional DSA imaging technology would make it difficult to distinguish because of the overlapping of the cerebral blood vessels in the image. Therefore, 3D DSA should be extensively used [12].

The secondary brain injury caused by moyamoya disease can be reflected by CT technology. Multislice spiral CT has been more widely used on account of its more powerful background processing function and higher resolution. The working principle of Blind image restoration algorithm based on improved sparse Bayesian low dose CT is to carry out continuous thin layer scanning through spiral CT, and then to collect the three-dimensional information of the target blood vessel for a variety of recombination. In this way, we are able to observe and study the vascular structure from different angles and directions [13]. Commonly used Blind image restoration algorithm based on improved sparse Bayesian low dose CT after-treatment methods are MIP, VR, MPR, and CPR, etc., and different treatment methods have different characteristics. MIP image can be used to achieve the enhancement of the overlapping of the blood vessels, and the results obtained are very close to the DSA image. Due to this, the influence of human factors can be reduced when we determine the stenosis, length and position of the small vessels, which means we would get more objective results [14]. Overall speaking, DSA has the disadvantages such as invasive, radiation and so on, which limit its widespread use, on the other hand, Blind image restoration algorithm based on improved sparse Bayesian low dose CT has a strong sensitivity and specificity. Its operation is simple and fast with high reliability and good practicability. Therefore, it is more suitable for the diagnosis and treatment of moyamoya disease [15]. DSA has some obvious disadvantages, such as longer radiation time, which limits its widespread use. Moreover, Blind image restoration algorithm based on improved sparse Bayesian low dose CT is more convenient and accurate in the treatment of vascular reconstruction and postoperative observation. Therefore, the use of Blind image restoration algorithm based on improved sparse Bayesian low dose CT technology turns out to be more acceptable in the diagnosis and treatment of moyamoya disease. The value of Blind image restoration algorithm based on improved sparse Bayesian low dose CT technology in the diagnosis and treatment of moyamoya disease can be analyzed through the in-depth research on it [16]. The specific procedures of CT in the diagnosis and treatment guidance and follow-up of the smoke disease are as follows:

3 Materials and methods

The inclusion criteria this time are in accordance with key points of cerebrovascular disease diagnosis established by the Chinese Institute of Neuroscience in China, which means the imaging performance needs to be consistent with the diagnostic criteria developed by the Japan Moyamoya Disease Research Council and excludes head and neck infection, Down syndrome, sickle cell anemia, glycogen storage disease etc. 105 moyamoya disease patients diagnosed by Blind image restoration algorithm based on improved sparse Bayesian low dose CT from April 2012 to November 2015 in our hospital were taken as the research objects. Among them there were 48 male patients (45.7%) and 57 female patients(54.3%). The ratio of male to female was 1:1.18. These patients aged from 18– 69. The maximum age gap is 51 years old, and the average age is 34.8 years old. In 105 cases, 65 cases were examined by DSA. In this group, 14 patients have hypertension or high blood lipids. Among these 14 patients, 3 patients have diabetes and 2 have hyperthyroidism at the same time. All patients had no family history. From the statistics we can know that the average age of onset was 34.8 years old, among them patients aged from 30 to 40 have as many as 43.

All 105 cases were adults. Ischemic stroke was performed in 41 cases and hemorrhagic stroke was found in 64 cases. The main clinical manifestations were headache, dizziness, limb weakness or sudden awareness, vomiting,etc. Because the clinical manifestations of MMD are complex, it needs some time to be diagnosed in the first episode to the final clinical diagnosis. The first symptom was expressed by cerebral hemorrhage and cerebral ischemia, and its specific manifestations were shown in Table 2.

Table 1
Clinical data of moyamoya disease patients

Variable Numerical value Remarks

Age Average age 34.8

Max/min 69/18

Gender Male/female 48/57

Male to female ratio 1:1.18

Complication High blood pressure or high blood fat 14

Complicated with diabetes 3

Combined hyperthyroidism 2

Variable	Numerical value	Remarks
Age	Average age	34.8
	Max/min	69/18
Gender	Male/female	48/57
	Male to female ratio	1:1.18
Complication	High blood pressure or high blood fat	14
	Complicated with diabetes	3
	Combined hyperthyroidism	2

Table 2

Clinical symptoms of moyamoya disease patients (25 cases)

First symptoms	Male	Female
Cerebral ischemia
Cerebral infarction	13	11
TLA	6	5
Dizziness, epilepsy	2	4
Cerebral hemorrhage
Intracerebral hemorrhage	8	11
Simple ventricular hemorrhage	14	20
SAH	5	6
Total	48	57

Table 3

Reconstructive surgery(31cases)

STA-MCA bypass+EDMS			Temporal muscle sticking and dural turnover
Right	Left	Bilateral	2
11	17	1

The patient’s examination should be determined combined with laboratory examination, vascular ultrasound examination and imaging examination. Continuous imaging tracking in the process of diagnosis and treatment is also necessary to guide the clinical treatment. Laboratory examination involves liver and kidney function, blood glucose, blood lipids, etc., In addition to this; it also includes thyroid function, rheumatism series, the first four blood transfusion and anti nuclear antibody spectrum, etc... TCD examination uses the cerebral blood flow detector to check the majority of the blood vessels of Willis ring in the skull base, such as bilateral anterior cerebral artery, bilateral middle cerebral artery and branch, recording the data of PSV, MFV, EDV and PI of blood vessels. The most vital examination is imaging examination. All the 105 patients underwent CT plain scan and CT angiography, and GE Light speed VCT of 64 rows and 128 layers was adopted. The scanning parameters are 120KV, 500 mA. Layer thickness is 0.625 mm, and the field of view is 250 mm.SmartPrep software is used to determine the scanning delay time. It is noticeable that scan should be started after injecting contrast medium15– 20 s later to obtain the arterial phase images of intracranial vessels. Image after-processing uses ADW4.5 workstation. The maximum intensity projection (MIP), multi planar reconstruction (MPR), volume rendering (VR), curved planar reformation (CPR) and vascular analysis are respectively used for vascular remodeling. DSA examination uses the multi-functional digital imaging machine manufactured by Holland Philip Company to perform angiography of whole cerebral vessels. The total injection volume and flow rate of the vertebral artery and carotid artery are 4 ml/s and 6 ml. Image acquisition speed is 3 ∼ 8 frames /s, including the capillary phase, arterial phase and Venous sinus and other vascular images.

According to the clinical characteristics and examination results of different patients, we select target therapy for them individually. Surgical treatment and medical treatment. The specific conditions of surgical reconstruction are as follows:

The selected 31 cases of patients underwent surgical reconstruction surgery, 29 cases of successful STA-MCA +EDMS bypass surgery, were left in 17 cases, 11 cases on the right side; surgery were 1 cases at an interval of 7 months; the other 2 patients with intraoperative cut the dura mater was not found the right cortex blood vessel are only for temporal muscle sticking and dural turnover.

Another part of the blood group of patients with cerebral stroke patients also carried out the removal of hematoma of the brain and bone valve decompression and ventricular puncture drainage and other surgical treatment of symptomatic treatment; the rest of the patients only medical treatment of symptomatic conservative treatment.

4 Results

Through the analysis of the imaging results of CT plain scan and Blind image restoration algorithm based on improved sparse Bayesian low dose CT (see Fig. 3) before operation we can know The location of the lesion, patient involvement, whether extracranial collateral circulation, and the superficial temporal artery and middle cerebral artery ipsilateral cortical branches of walking and diameter were evaluated for the follow up treatment. As to CT plain scan, there are only 17 patients’ plain scanning showed normal among 41 patients with ischemic stroke. 24 patients have multiple cerebral infarctions, and infarction lesions are mainly located in the basal ganglia region, frontal lobe or semi oval center. There are as many as 64 cases of ischemic stroke. Among them, 34 cases showed ventricular hemorrhage, 11 cases of subarachnoid hemorrhage and 19 cases of intracerebral hemorrhage in the cerebral ventricles or simple intracerebral hematoma.

Fig. 1

Imaging characteristics of patients with Moyamoya disease.

Fig. 2

Diagnostic flow chart of cerebral stroke caused by MMD (Blind image restoration algorithm based on improved sparse Bayesian low dose CT).

Fig. 3

Preoperative imaging evaluation.

Moyamoya disease was found in all 105 cases, among which 86 cases were bilateral lesions and other 19 cases were unilateral lesions. 32 out of 105 were also found with posterior cerebral artery disease. Through the reconstruction of VR and MIP image as well as the enhancement of the original fault image, we could detect tortuous and messy vascular network mainly distributed in the periphery of the Willis ring at the bottom of the brain. Vessel wall incrassation was found in 12 patients based on CPR imaging, vascular analysis and primitive tomography, accompanied with calcified plaque and soft calcified plaque. In 105 cases, 4 branches of the internal carotid artery were the entire lesion, and 3 of them were occlusion and 1 was stenosis. The stenosis showed fine whole process and rough tube wal. In 23 cases, the external carotid artery supplied blood to the brain. The main manifestation was thickening of frontal or parietal branch of superficial temporal artery, which entered the brain through the cranial suture to supply blood based on the consistency with pial vessels. Secondly was the middle cerebral artery. 18 cases were aneurysm, which were located in the anterior communicating artery, the end of the basilar artery, the P1 segment of the posterior cerebral artery and the proximal segment of the posterior cerebral artery.

①∼② show the location and range of lesions; ③∼④ showed posterior circulation and external carotid artery compensatory; ding176 with left posterior cerebral artery aneurysm; ding177 showed superficial temporal artery and middle cerebral artery cortical branch and diameter.

After comparing and analyzing the results of DSA examination and Blind image restoration algorithm based on improved sparse Bayesian low dose CT examination in 65 cases (Fig. 4), we found that the results of these two methods are consistent. Therefore, in terms of examination of preoperative imaging, the imaging of DSA and Blind image restoration algorithm based on improved sparse Bayesian low dose CT used for evaluation of patients with moyamoya disease before operation are almost the same.

Fig. 4

Comparison between DSA and Blind image restoration algorithm based on improved sparse Bayesian low dose CT.

29 patients underwent STA-MCA bypass + temporal muscle sticking + dural turnover postoperative respectively at different time period of repeated Blind image restoration algorithm based on improved sparse Bayesian low dose CT (specific see Fig. 5), VR, MIP image can clearly show the graft patency, some patients also showed a new formation of collateral circulation; 1 cases in second days after the re-examination of CT scan that bypass side lobe acute large area cerebral infarction in 1 cases, third days and 51 year old male patient with postoperative loss of left upper limb muscle strength, no MRI review of the infarct after symptomatic treatment, clinical symptoms gradually improved, the postoperative hyperperfusion caused by. In addition because of the surgical treatment of cerebral hemorrhage patients in 1 cases of 69 year old female patient with rupture into ventricle drainage system to increase postoperative bleeding and death after basal ganglia hemorrhage, the remaining patients were found bleeding gradually absorbed, clinical symptoms gradually improved.

Fig. 5

Postoperative imaging evaluation.

➆∼➉ show the same patients with bone and subtraction of VR image and MIP image, ⑪∼⑫ show the other patients with subtraction VR and MIP images, two patients underwent right STA-MCA bypass surgery +EDMS, bridge vessels clear, unobstructed, second patients with surgical lateral collateral circulation is rich.

5 Discussion

Moyamoya disease is mainly manifested as the stenosis or even occlusion of the internal carotid artery (ICA) of supraclinoidal portion and the branches of Willis ring. The incidence peak is before 10 years old and from 30 to 40 years old. Therefore, it can be divided into two types of children and adults in clinical. The incidence rate of adult is higher than that of children, and the incidence rate of female is higher than that of male. The study of the case in our hospital this time takes adults as the research objects instead of children. The specific clinical manifestations are: epilepsy, cerebral infarction, headache and other ischemic symptoms, As the age increases, the blood vessels will also be changed. When the age is above 25 years old, the clinical symptoms caused by sudden cerebral hemorrhage are conscious disturbance, speech disorder and so on. From the case analysis of this group we detected that 48 were male and 57 were female in a total of 105 cases. The ratio of male to female was 1:1.188. The number of female patients was slightly higher than that of male patients.

Adult-type moyamoya disease is often shown as hemorrhagic stroke, and a quite small number of patients have ischemic stroke. It is reported that incidence of cerebral hemorrhage in adults is approximately 68%. Women accounted for the majority. The clinical manifestations are ventricular hemorrhage, intra-cerebral hematoma or subarachnoid hemorrhage. Among them cerebral ventricular hemorrhage is the most common and subarachnoid hemorrhage is comparatively rare. Cerebral infarction focus of ischemic moyamoya disease often occurs in basal ganglia region, frontotemporal area and lateral ventricle. A few are in the occipital lobe. In this group of cases, 41 cases are ischemic type, accounted for 39% of the total number of cases, among which. 24 cases are cerebral infarction. 64 are cerebral hemorrhage, accounted for 61% of the total number of cases, With the main ventricle hemorrhage, accounting for 34 cases.

The diagnosis of moyamoya disease should meet the following three imaging criteria. The first criterion is stenosis or occlusion of internal carotid artery end (ICA), anterior cerebral artery (ACA) and proximal of middle cerebral artery (MCA). The second criterion is the abnormal vascular networks in the vicinity of the basilar artery occlusion. The last criterion is the bilateral invasion. If it is unilateral lesion, patients with typical clinical manifestations and angiographic manifestations can be diagnosed as unilateral moyamoya disease disease on the basis of the exclusion of other causes [17]. According to different stages of performance, Suzuki divided brain angiography into 6 periods. Most patients in this group were in the period of 2∼4 [18]. In the diagnosis of moyamoya disease, it is easy to confuse with the moyamoya disease syndrome, because the moyamoya disease imaging performance of the two is highly similar [19]. The syndrome is characterized by extreme stenosis or occlusion at the end of the internal carotid artery, and abnormal blood vessels will appear in the front and back of the cerebral arteries, usually accompanied by hyperthyroidism, arteriosclerosis, s’ Down syndrome and other diseases. Compared to the moyamoya disease, moyamoya disease syndrome is rare, and there are some differences between the two in pathology [20]. Through the study of the cases in the group we know that the adoption of Blind image restoration algorithm based on improved sparse Bayesian low dose CT for diagnosis can help us to clearly assess the patient imaging. Through comparative analysis of DSA imaging results we can also conclude that the image evaluation results of the two are consistent.

The first one is technology advantage. DSA is commonly recognized as the gold standard for the diagnosis of moyamoya disease. However, due to the large trauma, high cost and other reasons, its wide application has been restricted. Blind image restoration algorithm based on improved sparse Bayesian low dose CT can complete a large coverage of the continuous scan in a short time; in addition, it is particularly suitable for the critically ill emergency patients on account of its simple operation, lower price, and small wound. Blind image restoration algorithm based on improved sparse Bayesian low dose CT vertical resolution is comparatively high, and it is able to display all the arteries in the brain. At the same time, it has a powerful computer post-processing function. VR (volume rendering) three-dimensional reconstruction image can perform the multi-angle and multi-direction rotation with the bone or after the bone-subtraction to observe the twisted and overlapping blood vessels and the three-dimensional relationship with adjacent structures. The threshold value can be adjusted according to the specific needs, or the target blood vessel can be selectively displayed through the technology of VR blood vessel growth. Finally internal carotid artery system and vertebral basilar artery system can be clearly displayed on the whole or in parts through MPR (multi-planar reconstruction), MIP (maximum intensity projection), CPR (curved planar reformation), vascular analysis and other technologies. At the same time, the original axial images can also be observed in the blood vessel wall and so on.

The second one is diagnostic value of moyamoya disease. The main value of Blind image restoration algorithm based on improved sparse Bayesian low dose CT for the diagnosis of the disease is explained as follows. It shows stenosis or occlusion of the internal carotid artery and middle artery or anterior artery of brain. It also indicates the scope of involvement. Based on Blind image restoration algorithm based on improved sparse Bayesian low dose CT, we can tell that whether the tube wall is associated with plaque formation, morphology and properties of plaque, whether to combine with aneurysm and other vascular malformations. Besides, with the help of Blind image restoration algorithm based on improved sparse Bayesian low dose CT we can also observe abnormal vascular network and its distribution in the base of skull base. We are able to understand the associated brain tissue damage by contrasting the original fault images.

In accordance with the different stages developed by Suzuki, the treatment of moyamoya disease is also different. The use of Blind image restoration algorithm based on improved sparse Bayesian low dose CT can accurately assess the branches of superficial temporal artery and middle cerebral artery and the relationship with surrounding structures. Meanwhile, diameter can be measured (a direct reconstruction and anastomosis can be carried out only when the vascular diameter is above 0.8 mm). If the superficial temporal artery is not up to the request, we can also choose ipsilateral occipital artery to replace. In the course of operation, Blind image restoration algorithm based on improved sparse Bayesian low dose CT can be used to evaluate the surgical incision, the size of the bone flap and the separation range of superficial temporal artery, reducing surgical trauma to the greatest extent. We need to understand the collateral formed in the brain to prevent intra-operative damage. After the operation, the blood vessels can be shown in the whole course obviously with no stenosis or occlusion. It is easy to handle, combined with low radiation dose technology it can be used for the patient’s follow-up for many times. In this group of cases, Blind image restoration algorithm based on improved sparse Bayesian low dose CT was adopted to analyze and evaluate the preoperative, intra-operative and postoperative imaging, which has played a positive role in guiding the whole treatment.

6 Conclusions

In conclusion, Blind image restoration algorithm based on improved sparse Bayesian low dose CT can not only can diagnose moyamoya disease, but also reflect the vascular stenosis or occlusion and extent, skull base hyperplasia of abnormal vascular network distribution, collateral etc., to provide guidance for the treatment plan, and can be used for postoperative follow-up evaluation of vascular bypass patency and new collateral circulation formation. Blind image restoration algorithm based on improved sparse Bayesian low dose CT as an effective tool for evaluating cerebral blood vessels, has broad application prospects in the diagnosis, treatment guidance and postoperative follow-up of patients with moyamoya disease.

Footnotes

Acknowledgments

The study was supported by “Low-dose reconstruction algorithm of medical CT image blind restoration based on Bayesian compressive sensing, China (Grant No. 16JCYBJC28800)”.

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