Comparison between low-dose and standard-dose multidetector CT in patients with suspected chronic sinusitis

OBJECTIVE: This study was designed to compare low- and standard-dose multidetector CT (MDCT) findings in patients with suspected chronic sinusitis. SUBJECTS AND METHODS. Fifty patients underwent MDCT at 10 and 150 effective mAs. The low-dose MDCT protocol delivered a radiation dose of 0.047 mSv in men and 0.051 mSv in women, whereas the standard-dose MDCT protocol delivered a radiation dose of 0.70 mSv in men and 0.76 mSv in women. Scans of the right and left sides of sinonasal cavities were reviewed by three radiologists, with each physician reviewing a scan twice over an interval of more than 2 weeks. The reviewers were asked to evaluate the scans for eight mucosal and two bone abnormalities. We calculated the number of discrepancies in observed abnormalities between pairs of reviewers, among all three reviewers, and between findings on scans acquired with the two radiation doses. RESULTS: The mean number of discrepancies in observed abnormalities on scans acquired with different radiation doses ranged from 0 to 5.2. Discrepancies between pairs of reviewers ranged from 1.0 to 12.8 for low-dose scans and from 1.0 to 13.0 for standard-dose scans. Discrepancies among all reviewers ranged from 1.0 to 10.3 for low-dose scans and from 1.0 to 8.7 for standard-dose scans. In analyzing cases of significant discrepancies in observations, we found greater variation between pairs of reviewers and among all three reviewers than between findings obtained with different dose levels. CONCLUSION: Dose reduction played a far less important role in discrepancies of detected abnormalities than did the human element of reviewer observation. Given this finding and the fact that low-dose MDCT delivers a radiation dose that is no higher than that delivered by a four-view radiographic examination, low-dose MDCT should be considered the imaging method of choice in patients with suspected chronic sinusitis.     

Imaging evaluation of adult spinal injuries: emphasis on multidetector CT in cervical spine trauma

As computed tomography (CT) technology has evolved, multidetector CT has become an integral part of the initial assessment of many injured patients, and the spine is easily included in the total body screening performed in patients with severe blunt polytrauma. Despite all the advantages of multidetector CT, clearing the spine in which injury is suspected continues to be a daily challenge in clinical practice. The purpose of this review is to present the evidence and the controversies surrounding the practice of imaging in patients suspected of having spine injury. The discussion is centered on the increasing reliance on multidetector CT in the work-up of these patients but also considers the important contributions of clinical trials to select patient for appropriate imaging on the basis of risk and probability of injury. Available protocols, injury classification systems, and issues awaiting future research are addressed.     

CT在颈椎损伤中的诊断价值

目的：探讨CT扫描在颈椎损伤中的诊断价值。方法：回顾性分析32例颈椎损伤的CT与平片检查资料。结果：骨折28例（其中6例伴脱位）,单纯脱位4例,合并伤10例。结论：CT对颈椎损伤的检出率明显高于平片,能清晰显示其损伤的细节,并对判断失稳及椎管狭窄的程度均有重要价值。     

Comparison of low-dose and standard-dose helical CT in the evaluation of pulmonary nodules

The purpose of this study was to investigate the diagnostic accuracy of low-dose helical computed tomography by comparing the number of nodules detected at low- and standard-dose CT. The prospective study included 25 patients who were referred to CT scan for the assessment of pulmonary metastases. All patients underwent CT examinations at both standard- (200 mA, 120 kV, collimation 5 mm, table feed 10 mm per rotation) and low-dose (50 mA, 120 kV, collimation 5 mm, table feed 10 mm per rotation). The number of nodules detected at each protocol was recorded. The size of the nodules was measured electronically and categorized as <3, 3–4.9, 5–6.9, 7–9.9, and ≥10 mm. Finally, the nodules detected at only standard- or low-dose CT were assessed for the underlying causes of discrepancy. In 25 patients, 533 nodules were detected at standard-dose, whereas 518 nodules were observed at low-dose CT. There were no statistically significant differences in the number of nodules detected at standard- or low-dose CT (p>0.05). Four hundred ninety-one (87.7%) nodules were detected at both standard- or low-dose CT, 42 (7.5%) nodules were observed only at standard-dose CT, and 27 (4.8%) nodules were seen only at low-dose CT. The sensitivity of low-dose CT was 92.5% for all nodules, 88.1% for nodules <5 mm, and 97.4% for nodules ≥5 mm. No significant image artifact interfering with nodule detection was observed at low-dose CT. The low-dose CT protocol used in this study provided images of adequate quality; thus, it can be used reliably in the detection or exclusion of pulmonary nodules. Electronic Publication     

Cervical spine trauma: evaluation by multidetector CT and three-dimensional volume rendering

Multidetector-row computed tomography (CT) offers important advantages over conventional imaging modalities in the evaluation of the post-trauma cervical spine. It allows for faster scanning times, critical for triaging post-trauma patients as well as for eliminating motion artifacts, and allows for thinner collimation and the ability to achieve an isotropic data set which can be reformatted in any plane without loss of spatial resolution. In addition, three-dimensional volume-rendered reconstructions of images obtained using multidetector scanners can provide additional information in defining extent of injury, allowing neurosurgeons to see the fractures in any plane, simulating intraoperative views. 3D multidetector-row CT represents an advance in CT technology and can help ensure rapid, accurate evaluation of cervical spine injuries. Electronic Publication     

螺旋CT颈椎低剂量扫描及重建的临床价值评价

目的:探讨螺旋CT颈椎低剂量扫描及重建的临床价值及其可行性。方法:将需行颈椎椎体扫描的患者30例,随机分为常规剂量组和低剂量组,其中常规剂量组(CDG)10例,低剂量组(LDG)20例;并选择同期行椎间盘扫描患者20例作为对照组(CG),记录辐射剂量、有效剂量,原始图像及重建图像均传输至PACS系统,由2位经验丰富的放射科医师对图像质量进行评分;测量椎体周围肌肉及背景(空气)的CT值。采用F检验进行统计分析。结果:LDG的容积CT剂量指数(CTDIv-ol)为6.5 mGy,剂量长度积(DLP)为(98.21±2.47)mGycm,有效剂量(ED)为(0.53±0.01)mSv;CDG的CTDIvol为19.1 mGy,DLP为(287.84±27.94)mGycm,ED为(0.53±0.01)mSv;CG的CTDIvol为26.5 mGy,DLP为106.0 mGycm,ED为0.57 mSv。统计分析发现,CDG与LDG、CDG与CG的DLP差异有统计学意义(P=0.000);LDG与CG的DLP差异无统计学意义(P=0.326)。CDG与LDG、CDG与CG的ED差异有统计学意义(P=0.000);LDG与CG的ED差异无统计学意义(P=0.326)。椎体扫描低剂量组的辐射剂量少于常规剂量组。LDG原始图像得分为(4.48±0.24)分;CDG的原始图像得分为(4.60±0.23)分;CG图像得分为(4.51±0.19)分。组间比较椎间盘的图像评分差异无统计学意义(P0.05),LDG的图像得分均高于4分。LDG的肌肉组织及背景(空气)CT值的标准差(SD肌肉=6.1;SD背景=20.5)均大于CG(SD肌肉=3.2;SD背景=13.9)和CDG(SD肌肉=5.8;SD背景=2.3)。结论:采用螺旋CT行颈椎椎体扫描并重建具有可行性。优化参数可以明显减少辐射剂量。与单纯椎间盘扫描相比,该检查方法并没有增加患者的辐射剂量,而提供的信息却大大增加,因此更具有临床价值。     

A new low-dose CT examination compared with standard-dose CT in the diagnosis of acute sinusitis

A low-dose CT of the paranasal sinuses was designed with few, thin sections, non-uniform intersection gaps, low milliampere settings and avoidance of direct radiation to the eye lens. The low-dose CT was prospectively compared with standard-dose CT in patients with suspicion of acute sinusitis. Forty-seven patients were examined with low-dose CT immediately after standard-dose CT. The effective dose and the lens dose were calculated and compared. Using standard-dose CT as a gold standard the sensitivity and specificity of low-dose CT was calculated for each sinus group. The effective dose and the lens dose of the low-dose CT were reduced to, respectively, 3 and 2% of the standard-dose CT. The diagnostic yield of the low-dose CT with regard to acute sinusitis was good with a high specificity (≥96%) for all sinus groups. The sensitivity was also high (≥95%) except for the frontal sinus where the sensitivity was 83%. Low-dose CT offers considerable dose reduction and should be the standard for imaging patients with suspected acute inflammatory paranasal disease. Electronic Publication     

Application of multidetector CT in skeletal trauma

Multidetector computed tomography (MDCT) has improved our ability to image patients with skeletal trauma. The chief advantages of this technology include the extremely rapid scan times, the ability to produce very-high-quality multiplanar reformations, and the ability to reprocess raw data quickly and easily. Unlike soft tissue imaging, CT of bony structures requires high spatial resolution. Each joint in the body presents a unique challenge, and guidelines for imaging of each of the major joints is discussed throughout this article. In general, use of the thinnest slice width and a bone-reconstruction algorithm maximizes image quality. Imaging of larger joints such as the shoulder and hip requires slightly thicker slices to ensure reasonable image quality, particularly if surface rendering is to be performed. The demonstration of fracture line extension to articular surfaces is a key function of imaging, and image postprocessing is an integral component of high-resolution joint imaging. The introduction of MDCT has enabled submillimeter slice widths, ensuring unparalleled joint visualization in multiple planes from a single scan acquisition.     

Screening for cervical spine trauma with helical CT: experience with 676 cases

Purpose: CT scanners with helical capability are commonplace. Evaluation of multiple trauma patients using this technique is fast, and easily performed as part of the radiological evaluation. Our purpose was to ascertain the clinical effectiveness of cervical spine screening with helical CT in a large sample population of multitrauma patients. Materials and methods: A retrospective review was carried out using screening helical CT scans from multitrauma patients referred to the Massachusetts General Hospital emergency department. The radiographic diagnosis was evaluated and tallied along with the clinical diagnosis and outcome for each patient included in the study. Results: Six hundred seventy-six patients conformed to the inclusion criteria. In this series, 59 true-positive, 616 true-negative, 1 false-negative, and no false-positive findings were encountered. These data result in a sensitivity of 98.3 %, a specificity of 100 %, and an accuracy of 99.9 %. Conclusions: Screening helical CT in the evaluation of trauma patients has a high diagnostic accuracy, and is sensitive and specific in diagnosing clinically relevant fractures of the cervical spine.     

Efficacy of limited CT for nonvisualized lower cervical spine in patients with blunt trauma

Records of 100 patients with blunt injury and nonvisualization of C7 and T1 on cross-table lateral and swimmer's views were reviewed to evaluate the usefulness of limited computed tomographic (CT) scans in “clearing”¹ the lower cervical vertebrae of injury. CT was deemed necessary and performed in all of these cases because the lower cervical spine could not be evaluated clinically or with plain radiographs. Ninety-seven of these 100 patients had normal findings on CT and only three patients showed cervical spine fractures. All three had isolated and stable fractures. Two of these patients had “clay-shoveler” fractures at C6 and C7, respectively, and one had a single laminar fracture at C7. All three patients were conservatively treated. This study emphasizes the value of clinical correlation in the evaluation of cervical spine trauma. When deemed necessary in symptomatic patients, CT is useful to exclude skeletal injury in the lower cervical spine thus avoiding delay in the patient's workup and unnecessary hospitalization, and expediting patient discharge. Lack of pain and neurological findings in nonintoxicated, conscious, and alert patients is generally not associated with significant soft tissue or skeletal injury.     

Fracture detection in the cervical spine with multidetector CT: 1-mm versus 3-mm axial images

BACKGROUND AND PURPOSE: Multidetector CT imaging of the cervical spine performed with submillimeter collimation allows for the production of excellent quality multiplanar reformations and reconstructed axial images at any chosen section thickness. Currently there is no consensus on what images need to be reviewed for accurate diagnosis of cervical spine fractures. Our study assesses whether 1-mm axial images provide any diagnostic advantage over 3-mm images in detection of cervical spine fractures when read in conjunction with multiplanar reformations.MATERIALS AND METHODS: The dataset consisted 50 cases of CT of the cervical spine and included 25 consecutive cases of cervical spine fractures and 25 matched normal CTs. Axial images were reconstructed at 1- and 3-mm thicknesses, and the sagittal and coronal reformations between 2- and 3-mm thicknesses. Four radiologists reviewed all 50 of the cases twice, once at 1 mm and once at 3 mm. Reads were separated by 3 months.RESULTS: There were 39 fractures in total, consisting of 29 clinically significant and 10 insignificant fractures. Thirty-three fractures were missed in 400 reads. Twenty-one misses were at 3 mm (sensitivity, 86%), and 12 misses at 1 mm (sensitivity, 92%; P = .228). Ten of 33 misses were of clinically significant fractures, 6 misses at 1 mm and 4 at 3 mm (P = .52). Twenty-three of 33 misses were of clinically insignificant fractures, 6 at 1 mm and 17 at 3 mm (P = .006).CONCLUSION: For detection of clinically important fractures, there is no significant difference between 1- and 3-mm axial images when read in conjunction with multiplanar reformations.

Multidetector CT imaging of the cervical spine performed with submillimeter collimation allows for the production of excellent quality multiplanar reformations and reconstructed axial images at any chosen section thickness. The large image dataset and the ability to reconstruct a vast number of images leads to issues with data storage and time needed to review the examination. Currently there is no consensus on what images need to be reviewed for accurate diagnosis of cervical spine fractures. The standard in our institution is to read 1-mm axial images with sagittal and coronal reformations. The purpose of our study was to assess whether 1-mm axial images provide any diagnostic advantage over 3-mm images in the detection of cervical spine fractures when read in conjunction with multiplanar reformations, thereby providing objective data in the formulation of guidelines for the assessment of cervical spine CTs.     

Optimised low-dose multidetector CT protocol for children with cranial deformity

Objective

To present an optimised low-dose multidetector computed tomography (MDCT) protocol for the study of children with cranial deformity.

Methods

Ninety-one consecutive MDCT studies were performed in 80 children. Studies were performed with either our standard head CT protocol (group 1, n?=?20) or a low-dose cranial deformity protocol (groups 2 and 3). Group 2 (n?=?38), initial, and group 3 (n?=?33), final and more optimised. All studies were performed in the same 64-MDCT equipment. Cranial deformity protocol was gradationally optimised decreasing kVp, limiting mA range, using automatic exposure control (AEC) and increasing the noise index (NI). Image quality was assessed. Dose indicators such us CT dose index volume (CTDIvol), dose-length product (DLP) and effective dose (E) were used.

Results

The optimised low-dose protocol reached the following values: 80 kVp, mA range: 50–150 and NI?=?23. We achieved a maximum dose reduction of 10-22 times in the 1- to 12-month-old cranium in regard to the 2004 European guidelines for MDCT.

Conclusion

A low-dose MDCT protocol that may be used as the first diagnostic imaging option in clinically selected patients with skull abnormalities.

Key Points

? MDCT is a very useful tool in the study of skull lesions ? Low-dose MDCT minimises child exposure to ionising radiation while maintaining image quality ? Low-dose MDCT should be considered as the first imaging option in selected patients     

Comparison of multidetector CT angiography and MR imaging of cervical artery dissection

BACKGROUND AND PURPOSE: Conventional angiography has been historically considered the gold standard for the diagnosis of cervical artery dissection, but MR imaging/MR angiography (MRA) and CT/CT angiography (CTA) are commonly used noninvasive alternatives. The goal of this study was to compare the ability of multidetector CT/CTA and MR imaging/MRA to detect common imaging findings of dissection.MATERIALS AND METHODS: Patients in the data base of our Stroke Center between 2003 and 2007 with dissections who had CT/CTA and MR imaging/MRA on initial work-up were reviewed retrospectively. Two neuroradiologists evaluated the images for associated findings of dissection, including acute ischemic stroke, luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap. The readers also subjectively rated each vessel on the basis of whether the imaging findings were more clearly displayed with CT/CTA or MR imaging/MRA or were equally apparent.RESULTS: Eighteen patients with 25 dissected vessels (15 internal carotid arteries [ICA] and 10 vertebral arteries [VA]) met the inclusion criteria. CT/CTA identified more intimal flaps, pseudoaneurysms, and high-grade stenoses than MR imaging/MRA. CT/CTA was preferred for diagnosis in 13 vessels (5 ICA, 8 VA), whereas MR imaging/MRA was preferred in 1 vessel (ICA). The 2 techniques were deemed equal in the remaining 11 vessels (9 ICA, 2 VA). A significant preference for CT/CTA was noted for VA dissections (P < .05), but not for ICA dissections.CONCLUSION: Multidetector CT/CTA visualized more features of cervical artery dissection than MR imaging/MRA. CT/CTA was subjectively favored for vertebral dissection, whereas there was no technique preference for ICA dissection. In many cases, MR imaging/MRA provided complementary or confirmatory information, particularly given its better depiction of ischemic complications.

Dissection of the extracranial arteries accounts for 10%–25% of strokes in young and middle-aged patients.¹ It may be spontaneous or traumatic and can cause a variety of clinical presentations, including stroke, headache, neck pain, tinnitus, Horner syndrome, and cranial neuropathies.^1-4 Dissections are typically diagnosed on the basis of a combination of the clinical presentation, imaging studies (conventional angiography, CT/CT angiography [CTA], MR imaging/MR angiography [MRA], and sonography), and exclusion of other arterial disease, particularly atherosclerosis.^1,2,5 In patients with mild or atypical symptoms, noninvasive imaging may facilitate earlier diagnosis and prevent embolic ischemic complications with the use of antithrombotic therapy.^3,6Conventional angiography has historically been considered the gold standard for dissection diagnosis, but it has limitations, which include its cost and invasiveness.^1,7,8 Although the angiographic appearance of dissection is often characteristic, it does not assess the vessel wall for intramural hematoma; because of this feature, dissections in unusual locations or with atypical morphology may be misclassified or attributed to other processes. MR imaging/MRA and CT/CTA have emerged as viable alternatives for both diagnosis and follow-up of dissection.^9-15 In general, the 2 techniques have different strengths and weaknesses. Diffusion-weighted MR imaging is a powerful technique for detecting acute stroke,¹⁶ which may then lead to increased scrutiny of the upstream arterial tree. Axial T1-weighted fat-suppressed images can detect the methemoglobin of the intramural hematoma within the false lumen, a finding referred to as a crescent sign.^9,13 Multidetector CT/CTA has enabled routine acquisition of thinner sections with rapid imaging times, facilitating multiplanar and volume reconstructions. Additionally, it is more widely available (especially at night), has fewer contraindications, and provides greater spatial resolution than MR imaging/MRA. However, the use of ionizing radiation in the relatively young population of patients with dissection is potentially concerning, especially given the often frequent follow-up studies in these patients.Only 1 study to date has compared CT/CTA with MR imaging/MRA for evaluation of dissection, retrospectively reviewing 7 internal carotid dissections and showing CTA to be marginally more effective in the identification of the dissected vessel.¹¹ To our knowledge, this current study is the largest comparative series of cervical artery dissection imaged with both tomographic techniques. Given the higher spatial resolution of CT/CTA, we hypothesized that CT/CTA may be particularly suited to visualize dissections within the smaller vertebral arteries. Additionally, we hypothesized that in a series of known dissections, CT/CTA would be more sensitive to identify specific imaging features associated with dissections.     

低剂量与常规剂量16排螺旋CT扫描泌尿系结石的对比研究

目的 探讨根据体重指数(BMI)大小采用不同低剂量螺旋CT检查泌尿系结石的可行性.方法 对2009年9月至2010年2月本院100例临床拟诊泌尿系结石的患者,其中50例进行螺旋CT常规剂量(120 kV、240 mA)扫描,另外50例根据体重指数大小分别采用120、80和50 mA行低剂量扫描,其他扫描条件与常规剂量组相同.以临床诊断结果为标准,对比分析2种方法诊断泌尿系结石的敏感性、准确性和阳性预测值.结果 常规剂量组和低剂量组的剂量长度乘积(DLP)分别为(726.58±45.67)和(251.12±73.87)mGy·cm,CT剂量指数(CTDIvol)分别为18.95和6.65 mGy,两组辐射剂量差异有统计学意义(t=31.78,P＜0.01).低剂量扫描检查结石的敏感性为97.1%、准确性为94.0%、阳性预测值为94.3%,与常规剂量扫描组(97.3%、96.0%、97.3%)相比,差异无统计学意义(P＞0.05).结论 根据患者的体重指数采用不同的低剂量检查泌尿系结石是可行的,获得的图像质量可以满足临床诊断要求.

Abstract：

Objective To explore the feasibility to diagnose ureterolithiasis by 16-multidetector spiral computed tomography (16-MDCT) at different low doses based on body mass index (BMI).Methods A total of one hundred patients from 2009 Sep to 2010 Feb suspected of ureterolithiasis were randomly divided into 2 equal groups undergoing 16-MDCT at standard-dose (120 kV, 240 mA) or lowdose (120, 80, and 50 mA, respectively) based on the body mass index (BMI).Taking the clinical diagnosis as the standard, the sensitivity level, specificity level, and positive predictive value of these groups were compared.Results The dose length product ( DLP ) of the low-dose CT group and the average CT dose index (CTDIvol ) were 18.95 and 6.65 mGy, respectively.There was significant difference between the two groups ( t = 31.78, P ＜ 0.01 ).The sensitivity level, specificity level, and positive predictive value of the low-dose group were 97.1% , 94.0% , and 94.3% , respectively, all not significantly different from those of the standard-dose groups (97.3% , 96.0% , and 97.3% , respectively,P ＞0.05).Conclusions It is feasible to diagnose ureterolithiasis by low-dose 16-MDCT based on BMI with the obtained image quality meeting the clinical diagnostic requirements.     

MR imaging in cervical spine trauma

Continual improvements in MR imaging, technology and MR imaging-compatible monitoring and fixation devices have allowed the incorporation of this relatively new imaging modality into standard algorithms for cervical spine trauma assessment. The ability of MR imaging to define the type of spinal cord injury, the cause and severity of spinal cord compression, and the stability of the spinal column is unmatched. The heavy reliance of the spinal surgeon on MR imaging for decisions regarding the type of therapy, the timing, the approach of surgical intervention, and for predicting patient outcome attests to the usefulness of this modality.     

急性颈椎外伤的MRI诊断

目的 分析急性颈椎外伤的MRI征象,评价MRI在急性颈椎外伤诊断中的价值及限度。方法收集急性颈椎外伤150例,均有MRI检查和X线平片,15例有CT片,采用14个参数进行分析记录。结果150例中MRI检出骨折51个,小关节脱位30个,椎体脱位35个;外伤性椎间盘突出40个,硬膜外血肿2例;脊髓损伤69例;脊髓受压迫20例;前、后纵韧带损伤21例;棘间韧带和黄韧带损伤15例;椎前血肿或水肿30例;椎旁和背侧软组织损伤40例;X线平片发现椎体骨折55个,椎体脱位35个;小关节脱位35例,附件骨折25个,椎前软组织肿胀20例。15例CT均发现骨折,小关节脱位,椎管狭窄。结论MRI在显示脊髓、韧带、椎间盘和软组织损伤方面优于CT和X线平片。MRI能全面反映颈椎各种损伤的病理特征,为评估颈椎稳定性提供充分的依据;MRI和X线片的骨折检出率没有明显差异,CT应该用于复杂的颈椎骨折检查。     

Impact of MRI to clear the cervical spine after a negative CT for suspected spine trauma

Emergency Radiology - To describe the clinical presentation of trauma patients receiving a negative cervical spine MRI (CSMRI) after cervical spine CT (CSCT) without acute findings and calculate...