Justification of CT examinations in young adults and children can be improved by education,guideline implementation and increased MRI capacity

Objective:

To determine whether the justification of CT examinations performed on young patients can be improved by various interventions and whether these have an effect on the total number of CTs performed.

Methods:

Specific interventions—education, guideline implementation and increased MRI capacity—were introduced at the Oulu University Hospital, Oulu, Finland, following a previous study demonstrating unjustified use of CT examination in young patients. In the present study, the justification of 177 CT examinations of the lumbar and cervical spine, head, abdomen, nasal sinuses and trauma performed on patients aged under 35 years in 2009 was analysed retrospectively by looking at requests and corresponding patient files. The indications of the examinations were compared with the referral guidelines recommended by the European Commission. Results from our previously published similar study carried out before the interventions were used as a reference.

Results:

The proportion of justified CT examinations increased from 71% (141/200) in 2005 to 87% (154/177) in 2009 (p<0.001), and in the lumbar spine group from 23% (7/30) to 81% (22/27) (p<0.001). In the case of most of the unjustified examinations, MRI could have been performed instead. The total number of CT examinations carried out on young patients decreased by 7% (p=0.012) and in the lumbar spine group by 79% (p<0.001).

Conclusion:

The implemented interventions decreased the number of CT examinations performed on young patients, and the justification of the examinations improved significantly.

Advances in knowledge:

This study demonstrates that it is possible to reduce the number of various CT examinations and to improve their justification in young patients by regular education, guideline implementation and increased MRI capacity.By definition, a medical exposure is justified when the benefit to the patient is greater than the expected harm. In diagnostic imaging, justification inevitably includes consideration of any and all of the alternative procedures possibly available that require no or less exposure to ionising radiation [1,2]. Authoritative sources suspect that a considerable proportion of radiological examinations are inappropriate [3]. It is known that knowledge of radiation dose and related risks is poor among both physicians and radiologists, and risks are often underestimated [4–6]. The International Commission on Radiological Protection has emphasised that education, training and practice play a crucial role in improving the professionalism of justification [3].CT examinations are an essential part of current diagnostic radiology practice. The radiation exposure and dose from CT for both individuals and population are among the highest in diagnostic radiology. Although the risk from ionising radiation caused by a CT examination to a single individual is small, the concern is related to the current rapid increase in CT use [7,8]. In 2008, CT represented approximately 10% of all ionising radiation-based imaging globally, but delivered approximately 43% of the total collective dose [9]. In many European countries, CT-induced dose accounts for the largest proportion of the collective effective dose: approximately 68% in the UK, 59% in Norway, 58% in Finland and 60% in Germany [10–13]. The risk of potential radiation damage is higher in patients aged approximately 35 years or younger, owing to longer life expectancy and a possibly increased number of repeat examinations [14]. Developing organs are also more sensitive to radiation than those that are fully mature [15–17].We previously published a study demonstrating unjustified use of CT examinations in young patients at the Oulu University Hospital, Oulu, Finland, where 77% of CT examinations of the lumbar spine, 37% of the abdomen and 36% of the head were unjustified in 2005 [18]. After these results, we introduced various interventions involving provision of education, distribution of guidelines and increased MRI capacity. This study is therefore a re-audit, closing the audit loop [19]. Studies demonstrating the effects of different interventions on justification are sparse. The aim of the present study is to determine whether the justification of various CT examinations carried out on young patients has improved 4 years after the primary survey and whether the interventions applied have had an effect on the total number of CT examinations performed.     

成年人CT扫描中辐射剂量和诊断参考水平的探讨

目的 通过全国范围内CT辐射剂量的调查,了解成年人辐射剂量的现状,进而探讨成年人CT的诊断参考水平不符,需要根据我国的实际建立自己的DRL。方法 2015年9月至2016年3月在全国30个省、自治区、直辖市调查168家医院,其中三级和二级医院各约占一半。随机调查年度状态检测合格的168台CT,包括了临床应用中普遍使用的品牌和型号。每台CT收集头颅、鼻窦、颈部、胸部、腹部、盆腔、腰椎、尿路造影、冠状动脉CT血管造影（CTA）、颅脑CTA、颈部CTA和胸腹CTA共12个检查项目、每个项目10个随机病例。以容积CT剂量指数（CTDI_vol）和剂量长度乘积（DLP）作为剂量参量,每个检查项目的所有数据按照大小排序,取25%、50%和75%位数,其中75%位数为参考水平。所得剂量数值与国际相关放射防护组织发布的DRL进行比较。结果 共收集16 244个标准体型成年病例的剂量数据,经逐一检查剔除274个无效数据,剩余15 970个病例数据。全国范围内不同的CT使用单位,同一检查项目的CTDI_vol、DLP和扫描期项都有很大差异。与国际放射防护组织发布的数据相比,不同检查项目的诊断参考水平的差异程度各不相同,颅脑诊断水平与参考值相当、胸部腹部较低。剂量指数值最大的几种检查项目为头颅、冠状动脉CTA、颅脑CTA和鼻窦。尿路造影的CTDI_vol虽然仅为20 mGy,但DLP却高达2 620 mGy·cm。结论 我国现有的CT剂量水平与国际相关组织发布的诊断标准水平（DRL）不符,需要根据我国的实际建立自己的DRL。     

Computed tomography for cervical spine trauma. The impact of MDCT on fracture detection and dose deposition

A multidetector computed tomography (MDCT) was installed in our department. Referral rates, examination protocols and detection rates of abnormal findings in CT examinations for cervical spine trauma 6 months before and 6 months after MDCT installation were compared to look for changes in practice. Retrospective analysis of all CT cervical spine examinations in patients with multiple trauma over two contiguous 6-month periods: from July 2003 to December 2003 (helical CT) and from January 2004 to June 2004 (MDCT). Variables recorded were number of CT examinations performed, scan plane coverage and traumatic abnormalities detected. Phantom dosimetry measurements for cervical spine examination in both helical CT and MDCT were compared. One hundred and fifty four patients underwent cervical spine CT during these periods. Helical CT period: of 91 patients undergoing CT cervical spine examination for trauma, 65 (71%) were complete cervical examinations and 26 (29%) were level-specific examinations. Eight patients (9%) had cervical spine fracture, six of which were apparent on radiographs. Dose estimations for thyroid, lens and breast were 24.76, 1.86 and 0.21 mGy, respectively, for complete cervical spine examinations. MDCT period: of 63 patients who underwent CT cervical spine examination for trauma, 61 (97%) were complete examinations and 2 (3%) were level-specific examinations. Six patients (11%) had cervical spine fracture, three of which were apparent on radiographs. Dose estimations for thyroid, lens and breast were 75.8, 9.7 and 0.7 mGy, respectively, for complete cervical spine examinations, which were notably higher than those for helical CT. After installation of MDCT, clinical requests for complete examination of the cervical spine following trauma increased. This changing trend resulted in a significantly higher radiation dose to thyroid, lens and breast.     

淮安市CT检查致成年受检者的剂量水平及其影响因素调查研究

目的调查淮安市CT检查所致成年受检者的剂量水平,探讨本地CT诊断参考水平(DRLs)。方法选取全市45台CT,对医院信息、设备信息、扫描参数、辐射剂量表征量等信息进行调查。使用经验公式估算CT检查所致成年受检者的有效剂量。采用非参数秩和检验分析辐射剂量水平在CT役龄和医院级别等因素之间的差异。结果共收集3483例受检者剂量信息,头部890例、胸部890例、腹部846例、腰椎857例。头部、胸部、腹部、腰椎的容积CT剂量指数(CTDI_(vol))第75百分位数分别为63.0、12.4、20.0、24.0 mGy;剂量长度乘积(DLP)第75百分位数858.6、416.0、620.7、559.2 mGy·cm,男性的DLP第75%百分位数均高于女性。剂量水平随着设备役龄发生不同程度的偏移(头部:U=10326.00,P<0.05;胸部:U=36094.50,P<0.05;腹部:U=7859.00,P<0.05;腰椎:U=42408.00,P<0.05),不同级别医院之间同部位CT检查的辐射剂量差异也具有统计学意义(头部:H=14.28,P<0.05;胸部:H=17.85,P<0.05;腹部:H=97.18,P<0.05;腰椎:H=138.94,P<0.05)。结论淮安市CT辐射剂量水平与卫生推荐标准值基本一致,符合我国CT设备剂量水平现状。有必要加强CT设备的质量控制和保养力度。     

Establishment of CT diagnostic reference levels in Ireland

Objective To propose Irish CT diagnostic reference levels (DRLs) by collecting radiation doses for the most commonly performed CT examinations. Methods A pilot study investigated the most frequent CT examinations. 40 CT sites were then asked to complete a survey booklet to allow the recording of CT parameters for each of 9 CT examinations during a 12-week period. Dose data [CT volume index (CTDI(vol)) and dose-length product (DLP)] on a minimum of 10 average-sized patients in each category were recorded to calculate a mean site CTDI(vol) and DLP value. The rounded 75th percentile was used to calculate a DRL for each site and the country by compiling all results. Results are compared with international DRL data. Results Data were collected for 3305 patients. 30 sites responded with data for 34 scanners, representing 54% of the national total. All equipment had multislice capability (2-128 slices). DRLs are proposed using CTDI(vol) (mGy) and DLP (mGy cm) for CT head (66/58 and 940, respectively), sinuses (16 and 210, respectively), cervical spine (19 and 420, respectively), thorax (9/11 and 390, respectively), high resolution CT (7 and 280, respectively), CT pulmonary angiography (13 and 430, respectively), multiphase abdomen (13 and 1120, respectively), routine abdomen/pelvis (12 and 600, respectively) and trunk examinations (10/12 and 850, respectively). These values are lower than current DRLs and comparable to other international studies. Wide variations in mean doses are noted across sites. Conclusions Baseline figures for Irish CT DRLs are provided on the most frequently performed CT examinations. The variations in dose between CT departments as well as between identical scanners suggest a large potential for optimisation of examinations.     

Are cervical spine radiograph examinations useful in patients with low clinical suspicion of cervical spine fracture? An experience with 254 cases

Trauma patients with low clinical suspicion of cervical spine fracture are often examined with a plain X-ray cervical spine series rather than with cervical spine computed tomography (CT). The authors have been concerned by the absence of fractures in the group of patients examined with plain X-ray. The objective of this investigation was to determine the usefulness of plain X-ray examinations in suspected cases of cervical spine fracture compared to CT. A retrospective review was performed of all trauma patients undergoing imaging for suspected cervical spine fracture in our Emergency Department over a one-year period (January 1, 2007 to December 31, 2007). During the study period, 254 cervical spine plain X-ray and 3,080 cervical spine CT examinations were performed. Of the 254 plain X-ray examinations, 237 were interpreted as negative for fracture, 11 were suboptimal examinations, and six were interpreted as possible fractures (later ruled out by further imaging). Of the 3,080 CT examinations, 2,884 were interpreted as negative for fracture and 196 as positive. The overall positivity rates for acute cervical spine fracture were 0.0% in plain X-ray and 6.4% in CT examinations. These data confirm the authors’ concern that plain X-ray imaging for patients with low clinical suspicion for cervical spine trauma in our hospital may have too low a yield to justify its use. However, the 6.4% positivity rate in the group of patients selected for CT examination justifies its use in this group.     

Clinical demand for chest/abdomen/pelvis anatomy following thoracic or lumbar spine CT

The purpose of this study is to determine how often CT is repeated to obtain chest/abdomen/pelvis data outside the reconstructed field of view (FOV) on a prior spine CT. Radiology records of 1,239 consecutive thoracic and lumbar spine CT exams of 1,025 patients from January 1, 2006 to December 31, 2008 were retrospectively reviewed to identify patients who subsequently had CT studies of the chest, abdomen, and/or pelvis. The CT data were also evaluated for contrast enhancement, slice thickness, radiation dose, and reason for subsequent CT exam. Over 3 years, 290 of the 1,239 (24%) spine CT exams were followed by CT of the same anatomic region to evaluate extraspinal anatomy. The use or nonuse of contrast in these follow-up studies was the same as the preceding spine study in 91 cases, which were repeated on the same day (n?=?37), within 7 days (n?=?19), within 8-30 days (n?=?15), or after 30 days (n?=?20). Fourteen of 25 (56%) T spine CTs and 34 of 52 (65%) L spine CTs without contrast were followed by a chest CT or abdomen/pelvis CT without contrast within 7 days, respectively. Among 31 pediatric exams, 6 of 31 (19%) spine CTs were followed by a CT of the same anatomic region, all within 7 days. Reconstructing full FOV images of spine CT scans in addition to the standard coned down spine FOV may reduce redundant CT imaging and radiation dose.     

Adaptive statistical iterative reconstruction reduces patient radiation dose in neuroradiology CT studies

Introduction

Adaptive statistical iterative reconstruction (ASIR) can decrease image noise, thereby generating CT images of comparable diagnostic quality with less radiation. The purpose of this study is to quantify the effect of systematic use of ASIR versus filtered back projection (FBP) for neuroradiology CT protocols on patients’ radiation dose and image quality.

Methods

We evaluated the effect of ASIR on six types of neuroradiologic CT studies: adult and pediatric unenhanced head CT, adult cervical spine CT, adult cervical and intracranial CT angiography, adult soft tissue neck CT with contrast, and adult lumbar spine CT. For each type of CT study, two groups of 100 consecutive studies were retrospectively reviewed: 100 studies performed with FBP and 100 studies performed with ASIR/FBP blending factor of 40 %/60 % with appropriate noise indices. The weighted volume CT dose index (CTDI_vol), dose–length product (DLP) and noise were recorded. Each study was also reviewed for image quality by two reviewers. Continuous and categorical variables were compared by t test and free permutation test, respectively.

Results

For adult unenhanced brain CT, CT cervical myelography, cervical and intracranial CT angiography and lumbar spine CT both CTDI_vol and DLP were lowered by up to 10.9 % (p?<?0.001), 17.9 % (p?=?0.005), 20.9 % (p?<?0.001), and 21.7 % (p?=?0.001), respectively, by using ASIR compared with FBP alone. Image quality and noise were similar for both FBP and ASIR.

Conclusion

We recommend routine use of iterative reconstruction for neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality.     

Radiation dose and cancer risk from pediatric CT examinations on 64-slice CT: A phantom study

Objective

To measure the radiation dose from CT scans in an anthropomorphic phantom using a 64-slice MDCT, and to estimate the associated cancer risk.

Materials and methods

Organ doses were measured with a 5-year-old phantom and thermoluminescent dosimeters. Four protocols; head CT, thorax CT, abdomen CT and pelvis CT were studied. Cancer risks, in the form of lifetime attributable risk (LAR) of cancer incidence, were estimated by linear extrapolation using the organ radiation doses and the LAR data.

Results

The effective doses for head, thorax, abdomen and pelvis CT, were 0.7 mSv, 3.5 mSv, 3.0 mSv, 1.3 mSv respectively. The organs with the highest dose were; for head CT, salivary gland (22.33 mGy); for thorax CT, breast (7.89 mGy); for abdomen CT, colon (6.62 mGy); for pelvis CT, bladder (4.28 mGy). The corresponding LARs for boys and girls were 0.015-0.053% and 0.034-0.155% respectively. The organs with highest LARs were; for head CT, thyroid gland (0.003% for boys, 0.015% for girls); for thorax CT, lung for boys (0.014%) and breast for girls (0.069%); for abdomen CT, colon for boys (0.017%) and lung for girls (0.016%); for pelvis CT, bladder for both boys and girls (0.008%).

Conclusion

The effective doses from these common pediatric CT examinations ranged from 0.7 mSv to 3.5 mSv and the associated lifetime cancer risks were found to be up to 0.16%, with some organs of higher radiosensitivity including breast, thyroid gland, colon and lungs.     

CT of the spine: are plain spine radiographs necessary?

This study was designed to determine whether plain radiographs added any information of clinical significance to the information provided by CT (computed tomography) and its standard digital radiographs in 100 patients presenting for CT of the lumbar spine and 46 patients presenting for cervical spine CT. In only three (3%) of the lumbar studies and two (4.3%) of the cervical studies did the plain radiographs add diagnostic information. The added diagnostic information did not affect patient management in all cases with indications other than trauma. Good quality oblique cervical spine digital radiographs were obtained in 10 cases simply by moving the tube and detectors to the 45 degrees and 135 degrees azimuths. The evidence from this study suggests that when a CT examination of lumbar or cervical spines is planned on a high resolution CT scanner for indications other than trauma, a conventional plain radiographic examination can be omitted in the first instance.     

64层螺旋CT检查中患者受照剂量的研究

目的 对64层螺旋CT头部、胸部和腹部检查中患者受照剂量进行调查,确定有效剂量转换系数,为诊断方法的选取提供辐射剂量学方面的建议.方法 采用GE Lightspeed 64层螺旋CT机选取头部平扫48例、胸部平扫50例和腹部平扫45例患者,记录峰值电压(kV)、管电流(mA)、CT容积剂量指数(CTDIvol)和剂最长度乘积(DLP).采用SR 250软件计算患者有效剂量,将有效剂量除以DLP得到有效剂最转换系数.结果 头部、胸部和腹部CT平扫中患者有效剂量分别为:(3.1±0.1)、(6.9±0.1)和(8.0±0.1)mSv.有效剂量相对DLP的转换系数分别为:0.0025、0.0191和0.0166 mSv·mGy-1·cm-1.结论 建议采用CTDIvol、DLP和有效剂量监控患者受照剂量;采用有效剂量转换系数调查群体受照剂量、评估不同放射诊断的辐射风险及进行CT设备质量分析.     

Use of an automatic exposure control mechanism for dose optimization in multi-detector row CT examinations: clinical evaluation

PURPOSE: To prospectively compare dose reduction and image quality achieved with an automatic exposure control system that is based on both angular (x-y axis) and z-axis tube current modulation with dose reduction and image quality achieved with an angular modulation system for multi-detector row computed tomography (CT). MATERIALS AND METHODS: The study protocol was approved by the institutional review board, and oral informed consent was obtained. In two groups of 200 patients, five anatomic regions (ie, the thorax, abdomen-pelvis, abdomen-liver, lumbar spine, and cervical spine) were examined with this modulation system and a six-section multi-detector row CT scanner. Data from these patients were compared with data from 200 patients who were examined with an angular modulation system. Dose reduction by means of reduction of the mean effective tube current in 600 examinations, image noise in 200 examinations performed with each modulation system, and subjective image quality scores in 100 examinations per-formed with each modulation system were compared with Wilcoxon signed rank tests. RESULTS: Mean dose reduction for the angular and z-axis tube current modulation system and for the angular modulation system was as follows: thorax, 20% and 14%, respectively; abdomen-liver, 38% and 18%, respectively; abdomen-pelvis, 32% and 26%, respectively; lumbar spine, 37% and 10%, respectively; and cervical spine, 68% and 16%, respectively. These differences were statistically significant (P < .05). There was no significant difference in image noise and mean image quality scores between modulation systems, with the exception of cervical spinal examinations (P < .001 for both), where the examinations with angular modulation resulted in better scores. There is good correlation between the mean effective tube current level and the body mass index of patients with the new modulation system. Correlation was as follows: thorax, 0.77; abdomen-pelvis, 0.83; abdomen-liver, 0.84; lumbar spine, 0.8; and cervical spine, 0.6. This correlation was not observed with the angular modulation system. CONCLUSION: An automatic exposure control mechanism that is based on real-time anatomy-dependent tube current modulation delivers good image quality with a significantly reduced radiation dose.     

Changing Utilization Patterns of Cervical Spine Imaging in the Emergency Department: Perspectives From Two Decades of National Medicare Claims

PurposeThe aim of this study was to assess the changing use of emergency department (ED) cervical spine imaging in the Medicare population.MethodsUsing national aggregate Medicare claims data from 1994 through 2012, all cervical spine radiographic, CT, and MR examinations performed in the ED setting were identified. Shifts in modalities and providers and changes in utilization rates were studied.ResultsBetween 1994 and 2004, ED cervical spine radiography volumes in the Medicare fee-for-service population increased from 203,645 to 306,442 (+50.5%) and then declined to 152,755 (−50.2%) by 2012. CT volumes increased every year, overall by +8,864% from 1994 through 2012 (from 6,360 to 570,121). MR grew by +1,381%, but volumes overall were small (from 944 to 13,979). With these changes, CT overtook radiography as the dominant ED cervical spine imaging modality in 2007. Per 1,000 Medicare beneficiaries, utilization rates of radiography, CT, and MR changed by −27%, +8,682%, and +1,351% from 1994 through 2012 (from 6.3 to 4.6, from 0.2 to 17.3, and from 0.0 to 0.4). For all years, compared with other specialists, radiologists remained by far the dominant providers of radiography, CT, and MR (+91.7%, +93.4%, and +96.0% in 1994 and +96.9%, +99.3%, and +99.0% in 2012) in the ED setting.ConclusionsBetween 1994 and 2012, the overall utilization rate of cervical spine imaging for Medicare beneficiaries in the ED setting more than tripled. With a small decline in radiography (–27%) but a dramatic increase in CT (+8,864%), CT is now by far the dominant modality for imaging the cervical spine in the ED. Radiologists remain overwhelmingly the dominant providers of these interpretive services.     

Extraspinal abnormalities identified on lumbar spine CT

Summary Retrospective review of 1517 lumbar CT examinations revealed extraspinal pathology in 22 (1.45%). Retroperitoneal tumors and lymphadenopathy as well as vascular, urinary tract and gynecologic abnormalities were identified. This study demonstrates the need to carefully evaluate the visualized portions of the abdomen and pelvis on all lumbar spine CT examinations even when the patient's symptomatology is suggestive of spinal abnormalities.     

Compensation examination of the cervical and lumbar spines: critical disagreement in radiographic interpretation

Radiographic interpretation is often the major factor in the decision to award compensation for job-related complaints, especially in the Veterans Administration system. Three board-certified radiologists reviewed 200 consecutive lumbar and cervical spine examinations and assigned each case to one of three categories: normal, normal for age (not compensable), or degenerative disease (compensable). A critical disagreement, in which at least one radiologist considered the examination compensable and another not compensable, occurred in interpretation of 31% of the cervical and 46% of the lumbar spine examinations. Although the overall detection of radiographic findings was similar among all three radiologists, diagnostic interpretation of the findings varied greatly. Although most radiologists and orthopedists agree that the use of plain radiography of the spine as a deciding factor in awarding compensation is unjustified and inappropriate, until the regulations are changed there is a pressing need for strict, objective, radiographic criteria for determining "normal aging" of the cervical and lumbar spines so that interpreatations can be more uniform.     

Computed tomography whole body imaging in multi-trauma: 7 years experience

AIM: To assess the impact of the introduction of a computed tomography (CT) imaging protocol for multi-trauma patients on the workload, overall diagnostic yield, and effect on detection of cervical spine injury and pneumothorax. METHOD: Between February 1997 and April 2004, all patients presenting acutely to the Emergency Department (ED) with haemodynamically stable trauma (Abbreviated Injury Scale 3 or more) involving more than two body systems were imaged with a comprehensive pre-set helical CT protocol (including non-contrast head, cervical spine: cranio-cervical and cervico-thoracic junctions; and oral and intravenous contrast-enhanced thoracic, abdomen and pelvis) after initial triage and a standard trauma series of radiographs (chest, lateral C-spine and pelvis). Diagnosis of cervical spine fracture and pneumothorax was noted before and after the CT protocol was carried out and findings from all studies were recorded prospectively. RESULTS: Over the 7-year period 296 multi-trauma CT studies were completed of which 41 (13.8%) were negative. Of the positive cases there were 127 (43%) head injuries; 25 cervical spine fractures (8%); 66 pelvic fractures (22%);48 thoracic or lumbar spine fractures (16%); 97 pneumothoraces (33%); 22 mediastinal injuries (7%) and 49 intra-abdominal injuries (17%) with 19 (6%) splenic tears/ruptures. Positive findings included many unsuspected injuries, including 19 cervical spine fractures which were not demonstrated on the standard lateral radiograph from the resuscitation room. Of the 97 CT detected pneumothoraces, 12 were bilateral, 52 already had a chest drain in situ and 36 were not detected on initial supine chest radiography in the resuscitation room. One undetected case had bilateral tension pneumothoraces that were promptly drained on the CT table. Only three patients did not complete their multi-trauma examination because of deterioration in clinical condition and these were all immediately returned to the resuscitation room. CONCLUSION: Over the 7-year period in a large acute National Health Service (NHS) hospital trust currently averaging 85,000 ED attendances per year only 296 patients fulfilled the stated criteria for an immediate multi-trauma CT study. Although disruptive in the short-term, the overall impact on workload was small. A wide range of significant injuries were demonstrated rapidly, accurately and safely, including 19 cervical spine fractures and 26 pneumothoraces not detected on plain radiographs.     

Assessment of the spine with CT and MRI prior to interspinous/interlaminar spinal procedures: a pictorial review

Imaging of the spine is increasingly available, whether as dedicated spine examinations or as studies that include the spine in the images obtained (e.g. CT abdomen). This pictorial review discusses imaging of the spine with CT and MRI and how prior review of this imaging can be helpful with potentially difficult spinal procedures. Pathologies illustrated include osteoarthritis, scoliosis, inflammatory spondyloarthropathies and post-operative spines.Many spinal procedures are performed using the interspinous (midline) or interlaminar (paramedian) approach with high success rates. These procedures include myelograms for diagnosis, epidural corticosteroid injections for pain relief, central neuraxial blocks in regional anaesthesia and lumbar punctures for cerebrospinal fluid (CSF) analysis. The causes for difficult spinal procedures are wide in range and include pathological/anatomical conditions of the spine. As with all imaging as a whole, spinal imaging is increasingly more available with each individual patient [1], and review of such imaging can be helpful for difficult procedures.This pictorial review will discuss imaging (CT, MRI) of spinal conditions that can contribute to difficult spinal procedures, in particular osteoarthritis, scoliosis and the inflammatory spondyloarthropathies. The illustrations will focus on the interspinous/interlaminar approach for the thoracolumbar spine, but the principles provided can be used for other approaches.     

Low field (0.02 T) MR imaging of the whole body

The diagnostic utility of extremely low field magnetic resonance (MR) (0.02 T) was evaluated in various parts of the body outside the head. The areas investigated included the spine (104 patients), kidneys (19 patients), female pelvis (21 patients), and hips (15 patients). The results were compared with those of other imaging modalities, e.g., ultrasound, CT, and scintigraphy. Available pulse sequences and typical examination times for different types of studies are reported. Poor spatial resolution and long imaging times limit the application of this technique to the whole body. Due to poor signal-to-noise ratio, image quality is not comparable with that obtained at higher field strengths. In spite of these restrictions it was possible to demonstrate lumbar disk herniations, to differentiate renal and ovarian cysts from tumors, and to detect early avascular necrosis of the femoral head. Extremely low field MR imaging may eventually be used in screening spinal pathology and in the diagnosis of early avascular necrosis of the femoral head. At present, this technique can not replace ultrasound or CT in abdominal examinations.     

Xenon versus ceramics: a comparison of two CT X-ray detector systems.

PURPOSE: The purpose of this work was to compare image quality in phantom and patient CT scans acquired by xenon and ceramic CT detector systems. METHOD: High and low contrast resolution and image noise were determined with a standard CT phantom for both detector systems. In patient CT images, the effect on image noise was measured in anatomical regions of interest in the head, lumbar spine, chest, and abdomen. RESULTS: In phantom studies, image noise was significantly lower using ceramic versus xenon detectors. Also, in images of the head and lumbar spine, the signal-to-noise ratio was significantly higher with ceramic than with xenon detectors. In chest scans, ceramic significantly reduced beam-hardening artifacts caused by the thoracic spine. However, in abdominal images, the signal-to-noise ratio was not significantly different between ceramic and xenon detector systems. CONCLUSION: For reduced image noise in CT images of the head, lumbar spine, and chest and high resolution CT, ceramic detector systems appear to be superior to xenon detector systems.     

Repeated sinus CT imaging after recent head imaging

ObjectivesExcessive use of sinus CT is a significant problem in medical imaging, resulting in unnecessary costs and radiation exposure. This study assesses frequency of sinus CT performed after recent head imaging has already adequately evaluated the sinuses.MethodsA retrospective search of the PACS database of an academic medical center was performed to identify cases of sinus CT imaging in 2017. Cases were excluded if sinus CT was performed related to trauma, tumor, operative evaluation, or acute infection other than sinusitis (orbital cellulitis, intracranial abscess). Studies with separate imaging covering the sinuses ordered at the same time as sinus CT or performed previously within 4 weeks were identified and clinical information was recorded.ResultsOf 735 sinus CTs performed, 19 (5%) had same-day head imaging and 30 (8%) had previous head imaging within 4 weeks, adding up to a cumulative 13% of cases with recent head imaging. The average patient age was 42, with 13 pediatric cases. Of ordering providers, residents ordered the highest percentage of sinus CTs with same-day head imaging (84%) and previous imaging within 4 weeks (63%). The sinuses were described in all head CT radiology reports, while 10 of 12 brain MRI reports did not mention the sinuses.ConclusionIn one year, 13% of patients receiving sinus CTs at our institution had recent head imaging. A focused education effort for ordering providers to avoid repeating sinus imaging, and for radiology to comment on sinuses on head imaging, may reduce unnecessary sinus CTs.