PET/CT with intravenous contrast can be used for PET attenuation correction in cancer patients

Purpose If the CT scan of a combined PET/CT study is performed as a full diagnostic quality CT scan including intravenous (IV) contrast agent, the quality of the joint PET/CT procedure is improved and a separate diagnostic CT scan can be avoided. CT with IV contrast can be used for PET attenuation correction, but this may result in a bias in the attenuation factors. The clinical significance of this bias has not been established. Our aim was to perform a prospective clinical study where each patient had CT performed with and without IV contrast agent to establish whether PET/CT with IV contrast can be used for PET attenuation without reducing the clinical value of the PET scan.Methods A uniform phantom study was used to document that the PET acquisition itself is not significantly influenced by the presence of IV contrast medium. Then, 19 patients referred to PET/CT with IV contrast underwent CT scans without, and then with contrast agent, followed by an ¹⁸F-fluorodeoxyglucose whole-body PET scan. The CT examinations were performed with identical parameters on a GE Discovery LS scanner. The PET data were reconstructed with attenuation correction based on the two CT data sets. A global comparison of standard uptake value (SUV) was performed, and SUVs in tumour, in non-tumour tissue and in the subclavian vein were calculated. Clinical evaluation of the number and location of lesions on all PET/CT scans was performed twice, blinded and in a different random order, by two independent nuclear medicine specialists.Results In all patients, the measured global SUV of PET images based on CT with IV contrast agent was higher than the global activity using non-contrast correction. The overall increase in the mean SUV (for two different conversion tables tested) was 4.5±2.3% and 1.6±0.5%, respectively. In 11/19 patients, focal uptake was identified corresponding to malignant tumours. Eight out of 11 tumours showed an increased SUV_max (2.9±3.1%) on the PET images reconstructed using IV contrast. The clinical evaluation performed by the two specialists comparing contrast and non-contrast CT attenuated PET images showed weighted kappa values of 0.92 (doctor A) and 0.82 (doctor B). No contrast-introduced artefacts were found.Conclusion This study demonstrates that CT scans with IV contrast agent can be used for attenuation correction of the PET data in combined modality PET/CT scanning, without changing the clinical diagnostic interpretation.     

A new helical computed tomographic technique for appendiceal imaging: Preliminary experience with the focused appendix computed tomographic examination

Our objective was to describe a new, helical computed tomographic (CT) technique for evaluating appendicitis, the focused appendix CT (FACT), and report preliminary experience with its use.Thirty-five consecutive patients were selected on the basis of clinical suspicion for appendicitis. Patients received oral and colon contrast media but not intravenous contrast medium before CT scanning. A thinsection, contiguous helical scan limited to the lower abdomen and upper pelvis was performed. Each scan was interpreted as positive or negative for appendicitis, and any alternative pathology was noted, if present.Seventeen patients had a final diagnosis of appendicitis at surgery and pathology, and 18 patients had appendicitis excluded at clinical follow-up for at least 3 months (17 patients) or at surgeryand pathology (1 patient). FACT interpretations were correct in all cases. Alternative pathology was noted in 13 of the 18 cases (72%) interpreted as negative for appendicitis.     

Appropriateness of out-of-hours CT head scans

This study was conducted to evaluate the appropriateness of the out-of-hours computed tomography (CT) head scans (scans performed outside normal working hours) in a large district general hospital in the United Kingdom. CT scan request forms and CT reports of adult patients were reviewed who had their CT head scans done between 1700 and 0900 h the next day and all weekend and national holidays in the study period of 4 months. Information regarding change in the patient management resulting from CT scan was extracted from review of patients’ case notes. An urgent CT head scan request was deemed appropriate if it led to an immediate change in a patient’s management. Appropriateness of the requests according to the various guidelines was also evaluated. One hundred and twenty-one patients were included in the study. Majority (70%) of the scans were requested by the emergency department. Eighty-one (66%) scans were both requested and performed between 1700 and 2200 h. Immediate change in management of 80% patients occurred. In 20 (17%), the change in management occurred only after 0900 h the next day and in 4 (3%), management did not change at all. Common scenarios involving change in patient’s management included intracranial bleed requiring urgent neurosurgical intervention and hemorrhagic stroke being ruled out. Out-of-hours CT head scans also facilitated early discharge of the patients with head injuries and headache from the hospital. This retrospective study has found that a high proportion of out-of-hours CT head scans were appropriate and led to change in the patient’s immediate medical care. An Editor’s comment on this paper is available at and a reply to the comment is available at .     

Effect of bolus administration of non-ionic radiopaque contrast media on blood pressure variation

IntroductionHaemodynamic changes may occur with the rapid intravenous injection of contrast media due to the osmolality of such pharmaceuticals. This study sought to evaluate the effect of bolus administration of intravenous contrast media on blood pressure variation during the Contrast-Enhanced Computed Tomography (CECT) of the abdomen.MethodsThe study included 74 patients who underwent abdominal CECT and they were placed in the first group receiving a maximum of 80 ml of iodinated contrast via pressure injector (4 ml/s). A further 74 patients, who underwent non-contrast enhanced abdominal CT, were placed in the second group in which 80 ml of normal saline was administered via the same manner. Patients with hypertension and who were on anti-hypertensive drugs were excluded from the study. Non-invasive blood pressure was monitored before the injection of contrast media/saline and immediately after the portal venous phase for the CECT scan and after 45 s following the administration of normal saline in the non-contrast CT group. Mean systolic and diastolic blood pressures from both groups were compared to find out the effect of contrast bolus administration on blood pressure variation.ResultsBoth systolic and diastolic blood pressure increased with the injection of contrast media among CECT scan group. No significant changes in systolic and diastolic blood pressure were found before and after the scan in the non-contrast group.ConclusionBolus administration of 80 ml saline has no effect on blood pressure. The increased blood pressure in contrast enhanced studies was induced by the iodinated contrast media and not by the bolus effect.     

能谱CT虚拟平扫替代常规平扫评估甲状腺结节的可行性研究

目的探讨能谱CT碘抑制(MSI)成像作为虚拟平扫(VNC)替代真实平扫(TNC)对甲状腺结节进行评估的可行性。方法回顾性分析2014年2月—10月于我院行常规平扫、能谱成像模式增强扫描的72例甲状腺疾病病人影像资料,采用配对t检验和Wilcoxon符号秩和检验比较TNC与VNC影像上不同组织CT值、客观影像质量、主观影像质量评分、诊断钙化能力及辐射剂量的差异。结果 1在TNC和VNC两种影像上,甲状腺结节病灶、正常甲状腺、颈内动脉的CT值差异均有统计学意义(P0.05),但除正常甲状腺腺体外,其他部位CT值差异均不大(4 HU)。两种影像项部脂肪CT值的差异无统计学意义(P0.05)。VNC影像噪声高于TNC影像,信噪比(SNR)及对比噪声比(CNR)均低于TNC影像(P0.05)。2TNC与VNC主观影像质量评分中位数均为4.0分,VNC的主观评分略低于TNC,两者评分差异无统计学意义(P0.05)。3TNC检出钙化24例,VNC检出22例。TNC与VNC对钙化检出数目的差异无统计学意义(P0.05);TNC测得的钙化长径值较VNC大(P0.05)。4单独能谱增强扫描的剂量长度乘积(DLP)和有效辐射剂量(ED)值明显小于TNC加增强扫描(P0.05),与常规平扫加增强扫描比较,单独能谱增强扫描的有效辐射剂量可降低48.76%。结论在甲状腺CT扫描中,VNC成像对甲状腺结节的诊断具有替代TNC成像的潜在能力。     

Rapid CT scan visualization of the appendix and early acute non-perforated appendicitis using an improved oral contrast method

The purpose of this study was to optimize detection of the normal appendix in the clinical exclusion of acute nonperforated appendicitis using an improved and rapid method of bowel opacification in conjunction with the CT examination. A prospective evaluation of 100 consecutive patients, ranging from 13 to 50 years in age, was performed over a 4-month period using water-soluble oral contrast medium consisting of a fixed dose of diatrizoate salts administered as a prepared beverage in the emergency ward 50 min prior to performing a CT scan to evaluate clinical signs and symptoms of early acute appendicitis. The appendix was visualized in 84% (84 of 100) of patients, with a mean transit time of 50 min. The appendix filled with oral contrast medium in 89% (75 of 84) patients, and this sign was reliable in excluding appendicitis. In no instance did a contrast-filled appendix prove to represent appendicitis. The earliest signs of appendicitis were seen in 8% (8 of 100) patients. CT scan findings included absence of a contrast- or air-containing appendix with appendiceal thickening and infiltration of the periappendiceal mesenteric fat. CT scan utilizing a fixed dosage of orally administered water-soluble contrast containing diatrizoate salts, with a mean transit time of 50 min, provides a rapid and efficient means of visualizing the appendix in the clinical exclusion of appendicitis in the emergency setting.     

Evaluation of personal digital assistants as an interpretation medium for computed tomography of patients with intracranial injury

The objective of the study was to assess the feasibility of using a personal digital assistant (PDA) as a medium for the interpretation of cranial CT scans of trauma patients. Twenty-one noncontrast cranial CT scans were transferred in their entirety to a PDA from the picture archiving and communications system (PACS) utilizing General Electric (GE) PathSpeed PACS Web Server interface and synchronization. All CT scans had been interpreted by board-certified radiologists prior to the study. Seven of the scans demonstrated subarachnoid hemorrhage, seven demonstrated subdural hematomas, and the remaining scans were normal. After transfer to the PDA, all images were separately reviewed in a blinded manner by a radiologist and a neurosurgeon. Images were graded for their quality and diagnostic utility in the evaluation of intracranial hemorrhage. Image quality was categorized as excellent, very good, acceptable for diagnosis, or not acceptable for diagnosis. Based on the radiologic diagnosis, recommendation for surgical management was made by the reviewing neurosurgeon. The accuracy rate for both the radiologist and the neurosurgeon in the detection of intracranial hemorrhage was 95%. There was one false negative which was attributed to error in judgment rather than poor image quality. This diagnostic error did not affect patient management. The sensitivity and specificity for detection of intracranial hemorrhage were 93% and 100%, respectively. Image quality was judged to be excellent in 90% of the cases and very good in the remaining 10%. Our results suggest that the PDA is a robust medium for interpretation of CT scans in patients with suspected hemorrhage following intracranial injury. In this setting, the PDA should be considered for teleradiology purposes.     

CT appearance of the normal appendix in adults

The aims of this study were to identify (1) the normal range of the appendix on computed tomography (CT), (2) the correlation of patient age and sex with the visibility and appearance of the appendix on CT, and (3) the normal variations in wall thickness, intraluminal content, and location of the appendix. Three hundred seventy-two outpatients underwent abdominopelvic CT. The scans were reviewed on the picture archiving and communication system and appendiceal outer-to-outer wall diameter, wall thickness, location, content and its correlation with appendix diameter were analyzed. The appendix was visualized in 305/372 patients. Its location relative to the cecum was highly variable. The diameter range was 3–10 mm; in 42% of cases the diameter was greater than 6 mm. When the intraluminal content (185/305) was visualized, the diameter was slightly superior to the mean (p=0.0156). In 329 CT scans in which oral contrast material was given, the appendix was filled by contrast material in 74/329 patients. The appendix wall thickness was measurable in 22/305 patients (average 0.15 cm). There is significant overlap between the normal and abnormal CT appearance of the appendix. Consequently the diagnosis of acute appendicitis should be based not only on the appearance of the appendix but also on the presence of secondary signs.     

Is unenhanced CT sufficient for evaluation of acute abdominal pain?

Background: To determine whether intravenous contrast improves the ability of radiologists to establish the cause of acute abdominal pain after nondiagnostic or normal unenhanced CT. Methods: Out of 164 consecutive emergency department patients presenting with less than 48 h of nontraumatic, acute abdominal pain, a confident diagnosis for cause of pain was made prospectively in 71/164 (43%) patients on these unenhanced scans by the monitoring radiologist. In the other 93 patients, our study sample, intravenous contrast-enhanced CT was obtained. At a later date, retrospectively, two experienced abdominal CT radiologists independently evaluated unenhanced CT scans alone for potential causes of pain and diagnostic confidence level on a 1–3 scale. At least 2 weeks later, intravenous enhanced and unenhanced scans were read side-by-side for the same assessment. Results: There was no significant difference in diagnostic confidence levels comparing unenhanced CT alone (2.59) vs. intravenous enhanced and unenhanced CT together (2.64). Chi-square analysis found no significant difference in finding a cause for pain when intravenous contrast was added compared to the initial unenhanced scan alone. Conclusions: Intravenous contrast did not significantly improve the ability of CT to establish a cause of abdominal pain after a negative or nondiagnostic unenhanced CT.     

Regional lymph nodes of liver and spleen: topographic evaluation based on CT examinations of Thorotrast patients

The formerly used contrast medium Thorotrast is stored in liver (60%), spleen (30%) and their regional lymph nodes. CT scans of 22 Thorotrast patients were reviewed regarding the evaluation of the abdominal lymph nodes. Due to the high density of Thorptrast-accumulating lymph nodes (> 500 HU) and the excellen contrast sensitivity of CT, lymph nodes less that 0.4 cm in diameter can be imaged. In all more that 1300 lymph nodes could be detected (mean 63 ± 24 per patient). The goal of the study was to describe the normal topographic anatomy of the reginal lymph nodes of liver and spleen, which can not be visualised by bipedal lymphography.     

CT在急性小肠梗阻病因诊断和处理中的价值

目的　探讨CT在急性小肠梗阻病因诊断和处理中的价值。方法　回顾性分析经手术病理和临床随访结果证实的 5 5例小肠梗阻的CT征象和记录由于CT的信息而在治疗上发生的改变。进行腹部CT横断平扫和静脉增强扫描 ,2 4例进行冠状位重建。结果　 5 5例小肠梗阻的病因中 ,粘连性小肠梗阻 2 4例 ( 4 3 .6% ) ,小肠肿瘤 (含复发 ) 10例 ( 18.2 % ) ,腹外疝 5例 ( 9.1% ) ,炎性作用引起小肠梗阻 6例 ( 10 .9% ) ,肠套叠 4例 ,小肠扭转 2例 ,肠石性 2例 ,外伤后麻痹性肠梗阻 1例 ,先天性 1例小肠重复畸形。在CT检查前 ,病因诊断正确 2 3例 ( 4 2 % ) ,而CT提示正确病因诊断者 5 0例 ( 91% ) ,经CT确诊后 ,使临床治疗方案发生改变者 16例 ( 2 9% )。结论　CT扫描能够明显提高小肠梗阻的病因诊断正确率 ,并且提高了临床正确处理的能力     

Low-dose CT and inflammatory disease of the paranasal sinuses

Summary Computed tomography (CT) is the gold standard for exact delineation of inflammatory sinus disease, especially before endoscopic surgical treatment, and in cases of postoperative recurrences. In routine CT studies, the radiation dose to the patient is not negligible. Therefore, the authors evaluated prospectively the CT scans of 44 patients with inflammatory disease of the paranasal sinuses, to define the imaging ability of low-dose CT (i.e. 60 mA-3 s, 30 mA-3 s, and 30 mA-2 s), comparatively with the standard mAs settings (130 mA-3 s). In all cases, the exact extent of the disease was correctly assessed on each of the low-dose settings, with no false negative study. The increasing graininess of low mAs sections did not induce errors of interpretation, despite a less pleasant appearance to the eyes. In cases of extensive sinus disease, the thickness and integrity of the ethmoid septa were sometimes more difficult to evaluate on lowdose CT sections. The authors recommend the use of low mAs settings in the evaluation of inflammatory disease of the sinuses, complemented, if necessary, in cases of extensive abnormalities, by one or two sections obtained with standard mAs settings, focused on questionably abnormal bone septa.     

The Accuracy of Colorectal Cancer Detection by Computed Tomography in the Unprepared Large Bowel in a Community-Based Hospital

Purpose

This retrospective study examined the performance of general radiologists in a community-based hospital in detecting colorectal cancer (CRC) with computed tomography (CT) in the unprepared large bowel.

CT在脊椎转移中的应用价值探讨（53例影像学研究）

本文报告５３例（１２３个脊椎）经ＣＴ扫描确定的脊椎转移，其中２６例作Ｘ线平片检查，所有病例均经临床病理证实。原发性以肺癌、乳腺癌、肝癌和前列腺癌较多见，ＣＴ表现呈溶骨性３８例（７１．７％），混合性９例（１６．９％），和成骨性６例（１１．３％）。椎体是脊椎转移瘤最常累及的部位，这与血管进入脊椎的部位有关。转移最初的部位是椎体的后部，椎弓根破坏为堆体后部破坏扩展所致。ＣＴ扫描在发现病变和估价病变方面较     

Computer tomography versus aortography in diagnosis of aortic dissection

The use of computed tomography (CT) versus aortography is evaluated in a limited study of 17 cases of aortic dissection (AD). With the constraints of the present state of the technology and lack of availability of CT scanners at some centers, aortography remains the premier and often the only diagnostic test to choose in an emergency. CT, however, may be an asset in the diagnosis of AD when: (1) atypical or misleading clinical presentations are evident that do not require aortography; (2) aortography is contraindicated in a weakened patient, when there is no emergency; (3) aortography is a risk while there is a strong suggestion of AD; (4) patency of a false channel must be confirmed. These circumstances were encountered in five patients. In addition, a localized infrarenal AD was fortuitously discovered in two patients presenting with abdominal visceral cancer. On patient follow-up, CT is less invasive and may be performed in asymptomatic patients undergoing treatment, thereby facilitating the early detection of complications. Detailed computed tomograms often yield superior diagnostic information only if the CT study includes rapid sequential scans immediately following a fast intravenous bolus of contrast material.     

Service evaluation of radiographer-led vetting and protocoling of Computed Tomography (CT) scan requests in a Singapore public healthcare institution

IntroductionA service improvement project involving the vetting and protocoling of Computed Tomography (CT) scan requests by qualified CT radiographers was initiated in 2018.AimThis study provides a comprehensive evaluation of how a radiographer-led initiative aims to ensure that the CT scan requests received by the Radiology department are clinically appropriate, which in turn will reduce interruptions to the interpretation and reporting of imaging examinations by radiologists, who might otherwise be required to attend to clinically inappropriate and wrongly protocolled CT scan requests.MethodOutpatient CT scan requests received from July to October 2021 were vetted and protocolled by a qualified CT-trained radiographer for parameters which included the appropriateness of the clinical indication, adequacy of patient preparation for the scan, as well as the suitability of the requested examination protocol pertaining to the need for contrast media, multiple contrast-enhanced imaging phases, and the appropriateness of the scan range.ResultsPoor patient preparation and insufficient or inaccurate clinical indications were the most common findings during the vetting process (71%). Out of the 64 CT scan requests with protocol errors, 77% were attributed to contrast media type errors. The odds of incorrect CT scan requests increased with the requesting clinician’s rank, while there was no such significant correlation with the clinical specialty of the requesting clinician or the CT scan type.ConclusionThe meticulous vetting of imaging requests helps to ensure that limited imaging hardware resources are allocated to more clinically appropriate cases, correct protocols are applied to requested imaging scans, and that patients undergoing imaging are adequately prepared, thereby enhancing overall patient care.Implications for practiceVetting of imaging requests by radiographers, who are capable to make appropriate clinical decisions related to their enhanced level of practice ensures patient safety and optimisation of Radiology resources.     

Side-by-side reading of PET and CT scans in oncology: which patients might profit from integrated PET/CT?

Purpose Most early publications on integrated positron emission tomography/computed tomography (PET/CT) devices have reported the new scanner generation to be superior to conventional PET. However, few of these studies have analysed the situation where, in addition to PET, a current CT scan is available for side-by-side viewing. This fact is important, because combined PET/CT or a software-based fusion of the two modalities may improve diagnosis only in cases where side-by-side reading of PET and CT data does not lead to a definitive diagnosis. The aim of this study was to analyse which patients will profit from integrated PET/CT in terms of lesion characterization.Methods A total of 328 consecutively admitted patients referred for PET in whom a current CT scan was available were included in the study. The localization of all pathological PET lesions, as well as possible infiltration of adjacent anatomical structures, was assessed.Results Of 467 pathological lesions, 94.0% were correctly assessed with respect to localization and infiltration by either conventional PET alone (51.6%) or combined reading of PET and the already existing CT scans (42.4%). Hence, in only 6.0% of all lesions, affecting 6.7% of all patients, could evaluation have profited from integrated PET/CT.Conclusion We conclude that side-by-side viewing of PET and CT scans is essential, as in 42.4% of all cases, combined viewing was important for a correct diagnosis in our series. In up to 6.7% of patients, integrated PET/CT might have given additional information, so that in nearly 50% of patients some form of combined viewing of PET and CT data is needed for accurate lesion characterization.     

Diagnosis of acute appendicitis with unenhanced helical CT: a study of 130 patients

The aim of this study was to determine the sensitivity, specificity, and diagnostic accuracy of helical computed tomography (CT) without oral, intravenous, or rectal administration of contrast material in confirming the diagnosis of acute appendicitis in patients with suggestive clinical and laboratory findings. One hundred and thirty patients with suspected acute appendicitis underwent an unenhanced helical CT scan. Scans were obtained in a single breath-hold from the level of umbilicus to the pubic symphysis using a 5-mm collimation. Oral, intravenous, or rectal contrast materials were not used. The criteria for diagnosis of acute appendicitis included an enlarged diameter of appendix more than 6 mm with associated periappendiceal inflammation. The results yielded a sensitivity of 94.7%, a specificity of 91.7%, an accuracy of 93.8%, a positive predictive value of 96.7%, and a negative predictive value of 86.8%. Unenhanced helical CT accurately diagnoses acute appendicitis, and it protects the patients from unnecessary further time-consuming diagnostic procedures, the risks associated with contrast material administration, and unnecessary surgical interventions. Electronic Publication     

Blunt abdominal trauma: Computed tomography, ultrasound, or diagnostic peritoneal lavage: When and by whom?

The most important imaging decision that the clinician must make regarding the patient who sustains blunt abdominal trauma (BAT) is whether the patient is stable enough to undergo computed tomography (CT). CT is the most sensitive and specific examination for the evaluation of BAT. If the patient is unstable, the clinician has three choices: surgery, diagnostic peritoneal lavage, or ultrasound (US). If the patient then stabilizes, a CT scan should be obtained even if the US is negative.     

Small bowel obstruction: the role of computed tomography in its diagnosis and management with reference to other imaging modalities

Small bowel obstruction is a leading cause of acute surgical admissions for abdominal pain. There is an increasing tendency for initial conservative management rather than immediate operative intervention, as a proportion of cases will resolve spontaneously. This has resulted in a growing reliance on radiological investigations to reassure the surgeon that medical therapy can be safely instituted. The onus therefore rests with radiologists to guide their surgical colleagues by correctly interpreting the plain abdominal radiograph and suggesting appropriate further investigation if warranted. Recently, computed tomography (CT) has been proposed as the test of choice to define the level and cause of acute small bowel obstruction and to identify complications such as ischaemia and perforation which will prompt surgical intervention. This review will discuss the utility of early CT in the diagnosis of acute small bowel obstruction and outline its impact on patient management.