Amide proton transfer and chemical exchange saturation transfer MRI differentiates between growing and non-growing intracranial meningiomas: a pilot study.

AIM: To differentiate between growing and non-growing intracranial meningiomas using magnetisation transfer ratio (MTR) values with amide proton transfer (APT) and chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI). MATERIALS AND METHODS: Seventeen patients with suspected intracranial meningiomas who underwent APT-CEST MRI from November 2020 to April 2021 were evaluated retrospectively. MTR values on APT-CEST imaging as well as conventional MRI features were evaluated. These parameters were compared in growing meningiomas versus non-growing meningiomas and the findings compared with previous MRI examinations. ROC curve analysis was also performed to determine the diagnostic cut-offs for MTR. RESULTS: The cohort comprised 10 patients with growing meningiomas (two men [20%], eight women [80%]; mean age [standard deviation (SD)]: 59.9 years [16]) and seven patients with non-growing meningiomas (seven women [100%]; mean age [SD]: 63.9 years [18.6]). Significant differences were found in MTR values (0.0198 ± 0.0003 versus 0.0131 ± 0.0002; p<0.0001) between the growing meningiomas and non-growing meningiomas groups, respectively. The receiver operating characteristic (ROC) curve analysis showed that MTR values clearly differentiated between growing and non-growing meningiomas. At an area under the ROC curve (AUC) threshold of 0.0151, diagnostic sensitivity, specificity, positive predictive value, and negative predictive values for MTR were 100%, 85.7%, 90.9%, and 100%, respectively. CONCLUSION: Patients with growing meningiomas could be discriminated from patients with non-growing meningiomas, using the MTR values on post-growth tumour APT-CEST imaging.

Osteoporotic changes of subchondral trabecular bone in osteoarthritis of the knee: a 3-T MRI study.

SUMMARY: Subchondral trabecular bone structure was analyzed in knee osteoarthritis (OA) patients using 3-T MRI to investigate structural features of subchondral trabecular bone of knee OA. With OA progression, osteoporotic changes were observed in the lateral joint, showing a higher correlation than sclerotic changes in the medial joint. INTRODUCTION: To investigate structural features of subchondral trabecular bone of knee osteoarthritis (OA). METHODS: Sixty knees with KL grade 0-4 (all female) were examined. Fast imaging employing steady-state acquisition-cycled phases (FIESTA-c) and FatSat Spoiled gradient recalled acquisition in the steady state (SPGR) images were acquired by 3-T MRI. At four sites (the medial femur, medial tibia, lateral femur, and lateral tibia), subchondral trabecular bone structure was analyzed by FIESTA-c imaging, cartilage area was measured by SPGR imaging, and their correlation was analyzed. In addition, the subjects were classified into four groups from the cartilage area measured by SPGR imaging, and subchondral trabecular bone structure in each group was compared. RESULTS: As cartilage area decreased in the medial joint, bone volume fraction and trabecular thickness in the medial tibia increased, and bone volume fraction, trabecular thickness, number, and connectivity in the lateral femur and lateral tibia decreased (r ≥ 0.4 or ≤-0.4, p ≤ 0.001). Compared to medially, the changes laterally showed a higher correlation. When the medial-lateral ratio of trabecular thickness in the tibia was determined, it had the highest correlation coefficient (r=-0.7, p < 0.001). These changes were not significantly detected in the early stage. CONCLUSIONS: To more sensitively detect OA changes in subchondral trabecular bone structure, a focus on osteoporotic changes in the lateral joint and the medial-lateral ratio would be useful. Detectability of early OA remains unknown, but based on a strong correlation with the degree of OA progression, trabecular structural analysis of subchondral bone may be a useful parameter to evaluate OA severity and evaluate treatment.

In vivo structural analysis of subchondral trabecular bone in osteoarthritis of the hip using multi-detector row CT.

OBJECTIVE: With developments in clinical computed tomography (CT), in vivo analysis of patients' bone microstructure has become increasingly possible. We analyzed the subchondral trabecular bone of hip osteoarthritis (OA) patients using multi-detector row CT (MDCT) to closely examine the structural changes that occur as OA progresses. DESIGN: 47 female hip joints were studied: 20 with OA secondary to hip dysplasia (11 advanced OA, nine early-moderate OA), seven with hip dysplasia without OA, and 20 normal. The images' maximal spatial resolution was 280 × 280 × 500 µm. Regions of interest (ROIs) were the subchondral trabecular bones of the acetabulum and femoral head. Measurement parameters were bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), structure model index (SMI), trabecular bone pattern factor (TBPf), Euler's number, and degree of anisotropy (DA). Relationships between joint space volume and these parameters were analyzed. RESULTS: With decreasing joint space, Tb.Th and BV/TV increased, and Tb.Sp, Tb.N, SMI, TBPf, and DA decreased significantly. The microstructures were significantly different between the early to advanced OA groups and the normal and dysplasia groups; there was no significant difference between the normal and dysplasia groups. CONCLUSIONS: Changes of subchondral trabecular bone structure in OA could be evaluated using MDCT, despite imperfect spatial resolution and limited accuracy. Trabecular bone thickening and associated structural changes may be closely related to OA. Changes were observed in early to advanced OA, but not in dysplasia. This method may help to further elucidate OA pathogenesis, determine the therapeutic strategy, and evaluate therapy.

Usefulness of an artificial neural network for a beginner to achieve similar interpretations to an expert when examining myocardial perfusion images.

This study examined whether using an artificial neural network (ANN) helps beginners in diagnostic cardiac imaging to achieve similar results to experts when interpreting stress myocardial perfusion imaging (MPI). One hundred and thirty-eight patients underwent stress MPI with Tc-labeled agents. An expert and a beginner interpreted stress/rest MPI with or without the ANN and the results were compared. The myocardium was divided into 5 regions (the apex; septum; anterior; lateral, and inferior regions), and the defect score of myocardial blood flow was evaluated from 0 to 4, and SSS, SRS, and SDS were calculated. The ANN effect, defined as the difference in each of these scores between with and without the ANN, was calculated to investigate the influence of ANN on the interpreters' performance. We classified 2 groups (insignificant perfusion group and significant perfusion group) and compared them. In the same way, classified 2 groups (insignificant ischemia group and significant ischemia group) and compared them. Besides, we classified 2 groups (normal vessels group and multi-vessels group) and compared them. The ANN effect was smaller for the expert than for the beginner. Besides, the ANN effect for insignificant perfusion group, insignificant ischemia group and multi-vessels group were smaller for the expert than for the beginner. On the other hand, the ANN effect for significant perfusion group, significant ischemia group and normal vessels group were no significant. When interpreting MPI, beginners may achieve similar results to experts by using an ANN. Thus, interpreting MPI with ANN may be useful for beginners. Furthermore, when beginners interpret insignificant perfusion group, insignificant ischemia group and multi-vessel group, beginners may achieve similar results to experts by using an ANN.

Accuracy of pre- and postcontrast 3D time-of-flight MR angiography in patients with acute ischemic stroke: correlation with catheter angiography.

BACKGROUND AND PURPOSE: 3D time-of-flight (TOF) MR angiography (MRA) is insensitive to slow flow; however, the use of MR imaging contrast agents helps to visualize slow-flow vessels and avoids overestimation of vascular occlusion. The purpose of this study was to correlate pre- and postcontrast 3D TOF MRA with the results of conventional angiography during endovascular reperfusion therapy and to determine the accuracy of postcontrast 3D TOF MRA. MATERIALS AND METHODS: Thirteen patients who underwent endovascular reperfusion therapy for acute ischemic stroke were retrospectively analyzed. MR imaging techniques included single-slab 3D TOF MRA with and without contrast, as well as perfusion-weighted imaging. Angiography during reperfusion therapy was used as a standard of reference. Affected arteries were divided into segments either proximal or distal to the lesion, and pre- and postcontrast MRA signals were graded as absent, diminished or narrowed, or normal. RESULTS: In 2 of 5 patients with arterial stenosis and 6 of 8 patients with complete occlusion, MRA signal intensity proximal to each lesion was absent, indicating a proximal pseudo-occlusion on precontrast MRA. Postcontrast MRA demonstrated an arterial signal intensity proximal to the stenotic or occlusive lesions in all 13 patients. Arterial signal intensity distal to the occlusion was identified on postcontrast MRA in 7 of 8 patients having complete occlusion, and the extent of occlusion on postcontrast MRA was similar to results of conventional angiography. CONCLUSION: In this small series, postcontrast 3D TOF MRA more accurately delineated the extent of stenotic or occlusive arterial lesions than precontrast MRA.

Quantification of Lung Perfusion Blood Volume by Dual-Energy CT in Patients With and Without Chronic Obstructive Pulmonary Disease.

Purpose: In chronic obstructive pulmonary disease (COPD), pulmonary vascular alteration is one of the characteristic features. Recently, software has been used for the quantification of lung iodine perfusion blood volume (iPBV) using dual-energy CT, allowing objective evaluation. The purpose of this study was to evaluate the quantification of lung PBV with and without COPD. Materials and Methods: This study was approved by the Institutional Review Board. Sixty-two subjects who had undergone a respiratory function test within one month underwent dual-energy CT angiography. The subjects were divided into two groups: with (n = 14) and without (n = 48) COPD. We evaluated the quantification of lung iPBV in the early phase and late phase using Syngo softwarepost contrast. Associations between lung iPBV and respiratory function (forced expiratory volume in 1 second/forced vital capacity; FEV1/FVC) and the percentage area of emphysema (%LAA-950) were also evaluated. Results: In the early phase, lung iPBV values were 20.1 ± 5.5 and 30.6 ± 7.6 Hounsfield Unit (HU) in those with and without COPD, respectively, with a significant difference between them (p < 0.0001). In the late phase, the values were 12.3 ± 3.7 and 15.3 ± 4.6 HU, respectively, with no significant difference (p = 0.051). However, this could be noticed as a trend. In the early phase, there was a weak significant correlation between lung iPBV value and FEV1/FVC (R = 0.26, p = 0.047). There were significant and moderate negative correlations between lung iPBV value and %LAA-950 in early and late phases (R = -0.57, p = 0.0002; R = -0.45, p = 0.005, respectively). Conclusions: Quantification of lung iPBV reflects reduced pulmonary perfusion in patients with COPD. It may be useful for objective evaluation of the pulmonary blood flow in patients with COPD.

Efficacy and safety of systemic chemotherapy and intra-arterial chemotherapy with/without radiotherapy for bladder preservation or as neo-adjuvant therapy in patients with muscle-invasive bladder cancer: a single-centre study of 163 patients.

INTRODUCTION: Patients with muscle-invasive bladder cancer (MIBC) often undergo various preoperative treatments to improve survival; however, their efficacy and safety remain unclear. MATERIALS AND METHODS: The anti-tumour effects and adverse events were evaluated in 163 MIBC patients who received systemic chemotherapy (SC, n = 34), intra-arterial chemotherapy (IAC, n = 50), or combined IAC and radiotherapy (IAC + R, n = 79). RESULTS: Pathological complete responses were observed in 17.6%, 22.0%, and 43.0% of patients in the SC, IAC, and IAC + R groups, respectively, with respective 5-year overall survival rates of 42.0%, 46.7%, and 50.3%. Multivariate analysis showed that successful IAC + R protocol administration was a significant predictor for survival (hazard ratio = 0.16, p = 0.028). The incidence of severe adverse events was higher in the IAC + R group (36.7%) than in the SC (9.8%) and IAC groups (16.0%). CONCLUSIONS: IAC + R was useful for patients with MIBC. Successful completion and optimal patient selection were important for this treatment strategy.

Untreated Graves' disease patients without clinical ophthalmopathy demonstrate a high frequency of extraocular muscle (EOM) enlargement by magnetic resonance.

12 of 17, a significant frequency (71%), of untreated Graves' disease patients with no clinical ophthalmopathy showed extraocular muscle (EOM) enlargement by Magnetic Resonance Imaging (MRI). Enlargement was bilateral in 41% and unilateral in 29% in these patients. Apparent enlargements of EOM were also detected, by MRI, in all of 11 Graves' disease patients with clinical ophthalmopathy, bilateral in 73% and unilateral in 27% of patients in this group. Both group showed the inferior rectus muscle as the most frequently involved (56% and 77% respectively). In 16 patients without autoimmune thyroid disorders or ophthalmopathy who served as normal controls, only 2 of these patients (12%) demonstrated mild EOM enlargement. The severity and patterns of EOM enlargement revealed no correlation with abnormalities in serum thyroid function tests or serum thyroidal autoantibodies. In conclusion, a high frequency of Graves' disease patients without clinical eye signs or symptoms harbor EOM abnormalities, as demonstrated by MRI. This suggests that present clinical examination methods are insufficient to diagnose varying degrees of ophthalmopathy in patients with autoimmune thyroid disorders who do not initially present with clinical ophthalmopathy.

Differences of three-dimensional trabecular microstructure in osteopenic rat models caused by ovariectomy and neurectomy.

We investigated the differences in three-dimensional microstructure of bone in cases of osteopenia caused by two different procedures: ovariectomy (ovx) and sciatic neurectomy (nx). Thirty-nine 8-week-old female Lewis rats were divided into two groups: (1) ovx and sham operation; and (2) nx and sham operation. At 12 weeks of age these rats were killed to sample the right tibiae. The samples were scanned using microcomputed tomography to obtain metric parameters such as bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp), and nonmetric parameters such as structure model index (SMI), trabecular bone pattern factor (TBPf), and degree of anisotropy (DA). The changes in all microstructural parameters were significant in both the ovx and nx groups, with those of BV/TV, Tb.Th, Tb.Sp, and SMI more significant in the ovx group than in the nx group, in comparison to their respective controls. The significantly higher coefficient of variance for Tb.Th across the entire analyzed area of the individual samples indicated that the trabecular thinning occurred heterogenously and that the microstructural deterioration induced by ovx and nx appeared to be locally accelerated, so as to induce perforation and disappearance of trabeculae. The DA increased significantly in the ovx rats, whereas it decreased in the nx rats. The appearance of microstructural deterioration differed between the two osteopenic models. The three-dimensional (3D) images from the nx rats showed flake-like trabeculae, whereas the ovx rats exhibited a diffuse disappearance of trabeculae, especially in the central part of the tibia, but with a preservation of shape for those trabeculae that were retained. The reduction in cortical area was more significant in the nx group. nx and ovx resulted in significant changes in bone microstructure, showing perforation and removal of trabeculae due to locally accelerated bone resorption. The 3D microcomputed tomography images demonstrated the different microstructural changes that occurred in the ovx and nx groups. Loading during bone resorption increased the anisotropy, whereas immobilization increased the isotropy. In addition, immobilization had a more significant effect on the cortical area.

Contribution of trabecular and cortical components to the mechanical properties of bone and their regulating parameters.

To evaluate the mechanical contributions of the spongiosa and cortex to the whole rat vertebra, we developed a finite element analysis (FEA) system linked to three-dimensional data from microcomputed tomography (micro-CT). Twenty-eight fifth lumbar vertebrae (L-5) were obtained from 10-month-old female rats, comprised of ovariectomized (ovx, n = 6), sham operated (n = 7), and alfacalcidol-treated after ovx (0.1 microg/kg [n = 8] and 0.2 microg/kg [n = 7]) groups. The trabecular microstructure of L-5 was measured by micro-CT. Yield strength at the tissue level (YS), defined as the value at which 0.034% of all elements reached yield stress, was calculated by the FEA. Then, the ultimate compressive load of each specimen was measured by mechanical testing. The YS of the whole bone (YSw) showed a significant correlation with ultimate load (r = 0.91, p < 0.0001). The YS values of the isolated spongiosa (YSs) and cortex (YSc) were calculated in models with varying amounts of trabecular or cortical bone mass. The mechanical contribution of the spongiosa showed a nonlinear relationship with bone mass, and ovx reduced the mean mechanical contribution of the spongiosa to the whole bone by 13% in comparison to the sham group. YSs had a strong relationship with trabecular microstructure, especially with trabecular bone pattern factor (TBPf) and structure model index (SMI), and YSc had a strong relationship with cortical bone volume. The structural parameters most strongly related to YSw were BV/TV and TBPf. Our micro-FEA system was validated to assess the mechanical properties of bone, including the individual properties of the spongiosa and cortex, in the osteoporotic rat model. We found that the mechanical property of each component had a significant relationship with the respective bone mass, volume, or structure. Although trabecular microstructure has a significant relationship with bone strength, in ovx bone with deteriorated trabecular microstructure, the strength depended mainly on the cortical component.

The relationship of trabecular and cortical bone mineral density to spinal fractures.

RATIONALE AND OBJECTIVES: The relationships between trabecular, cortical, or integral bone mineral densities (BMD) to spontaneous vertebral fractures was investigated. METHODS: In 360 Japanese women, ranging from 20 to 83 years of age, vertebral trabecular and cortical BMD were measured using quantitative computed tomography (QCT). Among 46 oophorectomized women, BMD was measured using QCT and dual-energy x-ray absorptiometry (DXA). RESULTS: For patients in their sixth and seventh decades, those with fractures could be differentiated from those without fractures by measuring their trabecular BMD using QCT. Cortical BMD of women with fractures and trabecular BMD more than 80 mg/mL was significantly lower than that of women without fractures and trabecular BMD less than 70 mg/mL. CONCLUSIONS: Trabecular BMD can be a good predictor of spinal fracture. Cortical BMD may be important in cases with decreased trabecular BMD.

Association between anthropometric measures and spinal bone mineral density.

RATIONALE AND OBJECTIVES: The relationship of vertebral bone mineral density (BMD) to various anthropometric factors, including body weight and height, vertebral volume, and muscle area was examined. The sex- and menopause-related differences in these relationships also were studied. METHODS: Both cortical and trabecular BMD were measured using quantitative computed tomography (QCT). Integral BMD was measured using dual x-ray absorptiometry (DXA) in 74 men and in 96 premenopausal and 155 postmenopausal women. The psoas muscle area was measured using CT images. Vertebral volume was determined using CT images and CT topography. RESULTS: Bone mineral density had the strongest relationship with age in postmenopausal women. Trabecular BMD was correlated with muscle area and vertebral volume in premenopausal women, but not in postmenopausal women. The correlation of trabecular BMD with various anthropometric factors in men was stronger than that in women. Dual x-ray absorptiometry-BMD was found to be more affected by bone volume than was QCT-BMD. CONCLUSIONS: The association of anthropometric factors with BMD differs in men and women, as well as in premenopausal and postmenopausal women.

The aurora sign: an ultrasonographic sign suggesting parenchymal lung disease.

The objective of this study was to clarify the cause and clinical significance of a large number of ring-down artefact (RA) observed on the dorsal side of the right hepatic lobe on abdominal ultrasound (US). 2000 abdominal US examinations were evaluated to investigate the frequency and number of RA behind the right lobe of the liver. In this study, RA observed by subcostal or intercostal US were described as the "aurora sign" when they were numerous. US findings were correlated with high resolution CT or three-dimensional CT of the right lung base. Experimental study was also performed to investigate the mechanism of the aurora sign. The results were as follows. (1). Aurora sign was noted in 43 patients. In 37 of these 43 patients (86.0%), chest CT or plain radiography revealed diffuse interstitial changes in the right lower lung field. Three-dimensional CT of the lung and the experimental model revealed that the aurora sign derived from the irregularity of air spaces immediately below the pleura associated with interstitial pulmonary disorders. (2). One or more bands of RA were observed in 907 of the 2000 patients (45.4%). Of 177 patients with fatty liver, RA was observed in 14 (7.9%), while of the 1823 patients with no fatty liver, RA was observed in 893 (49.0%). The frequency of RA was significantly different (p<0.001) between the patients with and without fatty liver. In conclusion, parenchymal lung disease should be suspected when the aurora sign is noted on the dorsal side of the right hepatic lobe. However, RAs are rare in patients with fatty liver.

Case report: the "aurora sign"--a new sonographic sign of pneumatosis cystoides intestinalis.

Pneumatosis cystoides intestinalis (PCI) is a rare condition characterized by multiple gas-filled cysts of varying size within the intestinal wall. Although the characteristic findings on plain abdominal radiograph, computed tomography (CT), and barium enema have been well described, the sonographic findings have not. We recently encountered a case of PCI in which abdominal sonography disclosed a unique finding. We were able to reproduce the finding experimentally and have coined it the "aurora sign".

Clinical significance of a solitary hot spot in the skull.

Retrospective evaluation of bone scintigrams over the last 10 years was performed to determine the incidence of a solitary hot spot in the skull, examine its significance in patients with and without extra-skeletal malignancy, and determine if location along the suture lines is clinically significant or not. Review of the reports of bone scintigrams in 9968 patients yielded 37 (0.37%) patients with a solitary hot spot in the skull. In the group of 27 patients with extra-skeletal malignancy, the hot spot was secondary to metastasis in four patients and of a non-metastatic origin in 15. In the remaining eight patients, the cause was indeterminate. Two of the four metastatic foci were located along the suture lines. In another group of 10 patients without extra-skeletal malignancy, the cause was non-metastatic in eight patients and indeterminate in two. No significant differences between the scintigraphic features (intensity of uptake, location and relationship with sutures) of metastatic and non-metastatic foci were noted. We conclude that a solitary hot spot in the skull is rare and is predominantly benign in nature. However, in patients with known extra-skeletal malignancy, approximately 21% are secondary to a solitary bone metastasis of the skull. Location of a hot spot along the suture lines may not always be a normal variation and can represent a solitary bone metastasis.

Magnetic resonance imaging of rounded atelectasis.

This study describes the magnetic resonance imaging (MRI) findings of rounded atelectasis (RA) and compares them with computed tomography (CT) findings. The study sample comprised 15 cases of RA in which both MRI and CT were performed. The signal intensity of RA was higher than that of muscle and lower than that of fat on T1-weighted images, and similar to or lower than that of fat on T2-weighted images. The atelectatic mass homogeneously enhanced after gadopentetate dimeglumine administration. Structures within and surrounding the RA were clearly depicted on MRI. The pulmonary vessels and bronchi converging toward the area of atelectasis (comet tail sign) were better demonstrated by sagittal or oblique sagittal MRI in six cases. RA and thickened pleurae were more clearly separated on T2-weighted images compared with CT. An infolded visceral pleura was demonstrated as a low-signal-intensity line in seven cases, and a small amount of entrapped pleural effusion was noted in one case. Although MRI should not be performed in all cases of suspected RA, it is useful, especially in delineating the internal structure of RA, such as the infolded visceral pleura.

Anterior mandibular repositioning in a patient with temporomandibular disorders: a clinical and tomographic follow-up case report.

A 42 year old female with temporomandibular disorders (TMD) was treated by anterior mandibular repositioning which was followed-up clinically and tomographically. The authors tomographically reconfirmed the mandibular repositioning and discovered a type of condyle remodeling which they had not seen previously. Although clinical signs and symptoms of TMD were removed and the condyle was centered tomographically by the anterior repositioning, the MRI image indicated the disk was displaced anteriorly and laterally. The results suggest that image analysis of temporomandibular joint (TMJ) is beneficial and careful application of the treatment for anterior repositioning is recommended.

[Findings of MR and MR cholangiopancreatography in acute cholecystitis].

We retrospectively reviewed magnetic resonance cholangiopancreatography (MRCP) of 25 patients with acute cholecystitis based on clinical, sonographic and surgical findings. Intramural high signal intensity on MRCP was demonstrated in 22 of the 25 patients (88%), and pericholedochal high signal intensity was observed in 6 of the 25 patients (24%). Pericholecystic or perihepatic fluid was demonstrated in 6 of the 25 patients (24%). Gallbladder stones were identified in all 21 patients (100%) by sonography, in 19 of the 21 (90%) by MRCP and in 11 of 18 patients by CT (CT was not performed in other 3 patients). Common bile duct calculi were detected in all 6 patients (100%) by MRCP, in 2 of the 6 (33%) by sonography, and in 5 of the 6 (50%) by CT with confirmation of surgical finding or endoscopic retrograde cholangiography (ERC). MRCP had a high accuracy in diagnosing acute cholecystitis with the finding of intramural high signal intensity. MRCP is an excellent method to evaluate acute biliary disease and may replace CT and ERC in the preoperative evaluation of acute cholecystitis.

Fate of aorta and clinical outcomes in patients with chronic type B aortic dissection: over 20-year experience.

AIM: In type B double-barrel aortic dissection (AD), the fate of the affected aorta, causes of death, and very long-term clinical outcomes have not been completely elucidated. The purpose of this study was to clarify the fate of the affected aorta and long-term clinical outcomes in patients with type B AD during the chronic phase. MEHODS: One hundred and four patients were entered into this study, and regular follow-up CT studies (mean; 87.6 months) were performed. Also, clinical data including AD-related events (including aneurysm formation, rupture, ischemia, and re-dissection), AD-related deaths, and long-term survival were retrospectively reviewed. RESULTS: Forty-six of 104 patients (44.2%) had one more AD-related event during the follow-up period. The actuarial event-free rates for any AD-related events of all patients were 95±2%, 75±5%, 53±6%, and 13±7% at 1, 5, 10, and 20 years, respectively. Initial aortic diameter ≥40 mm and blood flow in the false lumen were significant risk factors for AD-related events in univariate and multivariate analysis. CONCLUSION: In type B chronic aortic dissection, the affected aortas have a high incidence of AD-related events during the follow-up period. Prophylactic surgery or endovascular treatment for patients at high risk may reduce the AD-related events.