Routine Computed Tomography Scan Research Articles

Intelligent 4D CT sequence scanning (i4DCT): First scanner prototype implementation and phantom measurements of automated breathing signal-guided 4D CT.

Four-dimensional (4D) computed tomography (CT) imaging is an essential part of current 4D radiotherapy treatment planning workflows, but clinical 4D CT images are often affected by artifacts. The artifacts are mainly caused by breathing irregularity during data acquisition, which leads to projection data coverage issues for currently available commercial 4D CT protocols. It was proposed to improve projection data coverage by online respiratory signal analysis and signal-guided CT tube control, but related work was always theoretical and presented as pure in silico studies. The present work demonstrates a first CT prototype implementation along with respective phantom measurements for the recently introduced intelligent 4D CT (i4DCT) sequence scanning concept (https://doi.org/10.1002/mp.13632). Intelligent 4D CT was implemented on the Siemens SOMATOM go platform. Four-dimensional CT measurements were performed using the CIRS motion phantom. Motion curves were programmed to systematically vary from regular to very irregular, covering typical irregular patterns that are known to result in image artifacts using standard 4D CT imaging protocols. Corresponding measurements were performed using i4DCT and routine spiral 4D CT with similar imaging parameters (e.g., mAs setting and gantry rotation time, retrospective ten-phase reconstruction) to allow for a direct comparison of the image data. Following technological implementation of i4DCT on the clinical CT scanner platform, 4D CT motion artifacts were significantly reduced for all investigated levels of breathing irregularity when compared to routine spiral 4D CT scanning. The present study confirms feasibility of fully automated respiratory signal-guided 4D CT scanning by means of a first implementation of i4DCT on a CT scanner. The measurements thereby support the conclusions of respective in silico studies and demonstrate that respiratory signal-guided 4D CT (here: i4DCT) is ready for integration into clinical CT scanners.

Comparison of spectral computed tomography imaging parameters between squamous cell carcinoma and adenocarcinoma at the gastroesophageal junction.

To compare the spectral computed tomography (CT) imaging parameters between squamous cell carcinoma (SCC) and adenocarcinoma (AC) at the gastroesophageal junction (GEJ). A total of 80 patients were enrolled in this retrospective study. Among them, 35 were diagnosed with SCC (SCC group) and 45 were diagnosed with AC (AC group). All patients underwent an enhanced scan with spectral CT. The following CT imaging parameters were evaluated: iodine concentration (IC), water content (WC), effective atomic number (Eff-Z) and slope of the spectral HU curve (λHU) of lesions. Receiver operating characteristic (ROC) curve was used to analyze the predictive value of spectral CT imaging parameters for diagnosis of SCC and AC. Patients with SCC had lower IC, Eff-Z, and λHU in arterial phase and venous phase compared with AC (p< 0.05). There were no significant differences in WC between the two groups. ROC curve analyses revealed that IC, Eff-Z, and λHU in arterial phase and venous phase were predictors for diagnosis of SCC and AC (AUC > 0.5). Moreover, the IC, Eff-Z and λHU in venous phase had better differential diagnostic performances than that in arterial phase. Spectral CT could be useful in the differential diagnosis of SCC and AC at the GEJ. Therefore, a routine spectral CT scan is recommended for patients with carcinoma of the GEJ.

Diagnostic efficacy of routine contrast-enhanced abdominal CT for the assessment of osteoporosis in the Turkish population

Background/aim This study aimed to evaluate the diagnostic efficacy of vertebral Hounsfield unit (HU) values on routine contrast-enhanced abdominal computed tomography (CT) scans for the assessment of osteoporosis using dual-energy X-ray absorptiometry (DXA) T-scores as a reference standard.Materials and methods A total of 111 consecutive patients who underwent contrast-enhanced abdominal CT examination for any indication and DXA within a 6-month period were retrospectively analyzed. The CT attenuation values of trabecular bone in HUs were measured in axial and sagittal planes from lumbar vertebrae 1–4 (L1–L4). The correlation between the DXA T-scores and HU values measured on the CT scans was evaluated by Pearson’s correlation test. Areas under the curves (AUCs) were calculated by receiver operating characteristic analysis for diagnostic proficiency, and threshold values were determined. Paired t-test and Bland–Altman plot test were used to evaluate the correlation between axial and sagittal HU values.Results There was a strong correlation between the DXA T-scores and HU values of all the lumbar vertebrae (P < 0.001). The highest correlation was for the L3 vertebra; L3 was thus chosen for additional analyses. The mean axial and sagittal L3 attenuations were 133.7 HU and 131.9 HU, respectively. The axial measurements were not significantly different from the sagittal measurements, with a mean difference of 1.8 HU (P > 0.05). The L3 axial CT attenuation threshold for 90% sensitivity was 170 HU and that for 90% specificity was 102 HU for distinguishing osteoporosis from osteopenia and normal bone mineral density (BMD). To distinguish the low BMD group from the normal group, the L3 axial CT attenuation threshold for approximately 90% sensitivity was 102 HU and for 90% specificity was 165 HU.Conclusion The HUs derived from routine contrast-enhanced abdominal CT scans can be used for the evaluation of osteoporosis, without additional radiation exposure and cost.

Computed tomography follow-up identifies radically treatable new primaries after resection for lung cancer.

The optimal imaging programme for the follow-up of patients who have undergone resection of primary lung cancer is yet to be determined. We investigated the incidence and patterns of new and recurrent malignancy after resection for early-stage lung cancer in patients enrolled into a computed tomography (CT) follow-up programme. We reviewed the outcomes of consecutive patients who underwent CT follow-up after resection of early-stage primary lung cancer at the Oxford University Hospitals NHS Foundation Trust, between 2013 and 2017. Four hundred and sixty-six consecutive patients underwent resection of primary lung cancer between 1 January 2013 and 31 March 2017. Three hundred and thirty-one patients (71.0%) were enrolled in CT follow-up. The median follow-up was 98 weeks (range 26-262). Sixty patients (18.2%) were diagnosed with programme-detected malignancy. Recurrence was diagnosed in 36 patients (10.9%), new primary lung cancer in 16 patients (4.8%) and non-lung primary tumours in 8 patients (2.4%). A routine CT scan identified the majority of new primary lung cancers (84.2%) and those with disease recurrence (85.7%). The majority of programme-detected malignancies were radically treatable (55%). The median survival of programme-detected cancers was 92.4 versus 23.0 weeks for patients with clinically detected tumours (P < 0.0001). Utilizing the CT scout image as a surrogate for chest X-ray, the sensitivity of this modality was 16.95% (8.44-28.97%) and specificity was 89.83% (79.17-96.18%). Negative likelihood ratio was 0.92 (0.8-1.07). CT follow-up of surgically treated primary lung cancer patients identifies malignancy at a stage where radical treatment is possible in the majority of patients. Chest X-ray follow-up may not be of benefit following lung cancer resection.

A Novel Algorithm for Segmentation of Solitary Pulmonary Nodules in Chest Computed Tomography Based on Three-Dimensional Connected Voxels

Background: With the increasing incidence of lung cancer, it is prudent to do screenings for individuals at high-risk. Solitary pulmonary nodules (SPNs) are an indication of small tumors or early stages of disease. Therefore, accurate detection of SPNs is important to both clinicians and radiologists. Since a large number of computed tomography (CT) scans are being acquired during a lung cancer screening, there is an urgent need for new automated techniques to detect SPNs. Methods: A novel algorithm for segmentation of SPNs in CT scans based on three-dimensional connected voxels (3DCVs) can be used to screen out potential patients with SPNs. 120 cases of CT scans from a public database (100 positive cases with nodules and 20 negative cases without nodules) and 30 negative cases from the routine CT scans completed in a hospital were used to test the algorithm. The algorithm is based on the fact that most pulmonary nodules are solitary at their early stages. First, find suitable CT values thresholds for CT values to convert pulmonary nodules, normal tissues and air spaces in each chest CT slice into black and white images. Then stack the slices in their originally physical order. This will produce a three-dimensional (3D) matrix with pulmonary nodules and normal tissues constructing their own 3DCVs respectively. Results: Of the 100 positive cases, 93 cases showed positive detection of SPNs and 7 cases did not. Of the 50 negative cases, 48 cases returned a negative result and 2 cases showed as positive result. In this study, the sensitivity is 93% and the specificity is 96% with a 4% false positive rate (FPR). Conclusions: This algorithm can be used to screen out positive chest CT scans efficiently, which will increase efficiency by two to three times than when compared with manual inspection and detection.

Computed Tomography for Detecting Cervical Lymph Node Metastasis in Patients Who Have Papillary Thyroid Microcarcinoma with Tumor Characteristics Appropriate for Active Surveillance.

Background: Active surveillance (AS) has been considered one of the management options in patients with low-risk papillary thyroid microcarcinoma (PTMC). It is important to evaluate clinical lymph node (LN) metastasis to select appropriate candidates with low-risk disease. We investigated the predictive accuracy of computed tomography (CT) for cervical LN metastasis in patients who have PTMC with tumor characteristics appropriate for AS. Methods: This was a retrospective study. Medical records from December 2014 to the end of 2016 were reviewed. Patients who underwent thyroidectomy and who had pathologically confirmed PTMC were included. A total of 464 patients who had tumors with ultrasound (US) characteristics appropriate for AS and who underwent preoperative CT were included in the analysis. Results: CT showed higher diagnostic values especially in positive predictive value (PPV) than US. In patient-based analyses, CT showed low sensitivity and negative predictive value (NPV) (16.0% and 58.5%, respectively), but high specificity and PPV (99.6% and 97.1%, respectively) for detecting cervical LN metastasis. Similar trends were observed for the results of the central neck-level by CT (sensitivity, 14.9%; specificity, 97.4%; PPV, 82.9%; and NPV, 57.4%) in level-by-level analyses. When restricted to lateral neck levels, CT showed high diagnostic accuracy of 95.4% for detecting LN metastasis. In all analyses, CT showed better diagnostic values for cervical LN metastasis than US. Combining US and CT did not improve the diagnostic accuracy compared with CT. Conclusions: In patients with PTMC whose tumor has characteristics suitable for AS, CT had additional benefit after cervical LN assessment by US. Further studies are needed to evaluate routine initial CT scanning for patients who are candidates for AS.

Biological fingerprint using scout computed tomographic images for positive patient identification.

Management of patient identification is an important issue that should be addressed to ensure patient safety while using modern healthcare systems. Patient identification errors can be mainly attributed to human errors or system problems. An error-tolerant system, such as a biometric system, should be able to prevent or mitigate potential misidentification occurrences. Herein, we propose the use of scout computed tomography (CT) images for biometric patient identity verification and present the quantitative accuracy outcomes of using this technique in a clinical setting. Scout CT images acquired from routine examinations of the chest, abdomen, and pelvis were used as biological fingerprints. We evaluated the resemblance of the follow-up with the baseline image by comparing the estimates of the image characteristics using local feature extraction and matching algorithms. The verification performance was evaluated according to the receiver operating characteristic (ROC) curves, area under the ROC curves (AUC), and equal error rates (EER). The closed-set identification performance was evaluated according to the cumulative match characteristic curves and rank-one identification rates (R1). A total of 619 (383 males, 236 females, age range 21-92years) patients who underwent baseline and follow-up chest-abdomen-pelvis CT scans on the same CT system were analyzed for verification and closed-set identification. The highest performances of AUC, EER, and R1 were 0.998, 1.22%, and 99.7%, respectively, in the considered evaluation range. Furthermore, to determine whether the performance decreased in the presence of metal artifacts, the patients were classified into two groups, namely scout images with (255 patients) and without (364 patients) metal artifacts, and the significance test was performed for two ROC curves using the unpaired Delong's test. No significant differences were found between the ROC performances in the presence and absence of metal artifacts when using a sufficient number of local features. Our proposed technique demonstrated that the performance was comparable to that of conventional biometrics methods when using chest, abdomen, and pelvis scout CT images. Thus, this method has the potential to discover inadequate patient information using the available chest, abdomen, and pelvis scout CT image; moreover, it can be applied widely to routine adult CT scans where no significant body structure effects due to illness or aging are present. Our proposed method can obtain accurate patient information available at the point-of-care and help healthcare providers verify whether a patient's identity is matched accurately. We believe the method to be a key solution for patient misidentification problems.

Stone-Free Rate after Treating Kidney Stones Exceeding 10 mm via Flexible Ureteroscopy: Can Endoscopic Assessment Replace Low-Dose Computed Tomography Control?

Introduction: It is unclear whether endoscopic assessment of the stone-free rate after flexible ureteroscopy (fURS) is as effective as assessment with low-dose computed tomography (CT) scan. Methods: Prospective documentation of patients with kidney stones > 10 mm diameter from 2 different centers (Freiburg, Regensburg), who underwent fURS and were declared to be endoscopically completely stone-free. Low-dose CT control performed 4–8 weeks postoperatively. Results/Conclusion: Thirty-eight patients were treated between October 2015 and August 2016 (12 F, 26 M). Average age was 55.9 years (range 19–82, SD 17.24), and body mass index was 29.7 kg/m² (range 23.5–42.5, SD 4.37). There were 2.0 (range 1–7, SD 1.55) stones with a mean diameter of 15 mm (range 10–40, SD 6.78) per kidney. Mean surgery time was 74 min (range 38–124, SD 24.28), and lithotripsy was necessary in 33 cases. CT was performed 5.4 weeks afterwards (range 4–8, SD 1.43). One patient had a 2 mm residual which was extracted by URS. Strictly speaking, endoluminal stone removal control failed in only that patient, yielding a negative predictive value of 97%. A routine postoperative CT scan would thus appear unnecessary in the case of negative endoscopic control for residual fragments and should be avoided to reduce radiation exposure. Further investigations with larger patient populations are necessary.

Assessing distal radius malrotation following fracture using computed tomography.

When the distal fracture fragment in distal radius fractures displaces, it commonly rotates as well as shortens and angulates. The aim of this study was to assess the frequency and magnitude of malrotation of the distal fracture fragment using computed tomography (CT). A retrospective radiological assessment of 85 CT scans of the distal radius, 35 following fracture and 50 normal radii, was carried out. We developed and applied a simple method for measuring rotation of the distal radius relative to the diaphysis using routine CT scans of the wrist. A Mann-Whitney analysis was used to identify differences in radial rotation between fractures and controls. Intra- and inter-observer reliability were analyzed using intra-class correlation coefficients (ICCs) and Bland-Altman plots. The articular surface of the distal radius is normally rotated in the long axis of the forearm relative to the diaphysis, either into pronation or into supination. The median radial rotation angle of controls was 1° pronation (range -15° to 4°) compared to 3° pronation (range -24° to 31°) in the fracture group. The absolute rotation angle was significantly greater in the fracture group (median 10°, range 0-31° vs. 3°, range 0-15°; p < 0.001) and outside the "normal range" of controls in 26 cases indicating that 75% had rotated appreciably following injury. Intra- and inter-observer reliability of measurements were good with ICCs of 0.99 and 0.98, respectively. Malrotation of the distal radius appears common following distal radius fracture. Malrotation of the distal fracture fragment has been shown to affect distal radio-ulnar joint function. Despite this, rotational deformity is rarely addressed in clinical practice as it is difficult to appreciate on simple radiographs. The simplified method described here is easy to use in routine clinical practice and also appears reliable. Measuring radial rotation may be an important consideration when planning both primary treatment and corrective osteotomy for patients with distal radial malunion.

Ectopic Eruption of Canine into Maxillary Sinus with Unusual Clinical Presentation: A Case Report and Review of the Literature

A 45-year-old female patient was referred by the neurologist to the maxillofacial surgery department for the management of an ectopic maxillary canine which was found in the left maxillary sinus during a routine computed tomography (CT) scan for an unusual left-sided facial pain with associated left unilateral headache that was refractory to all given medications. The duration of pain and headache had been on and off for 10 months with the last episode preceding the routine CT scan lasting >3 weeks. There was no history of sinusitis, nasal discharge, or nasal blockage. Intraoral examination showed missing upper left canine. A computed tomographic scan showed ectopic eruption of the left maxillary canine into the left maxillary sinus in close proximity to the infraorbital foramen with no associated antral pathology. Caldwell-Luc approach was employed to surgically extract the ectopic canine while preserving the left infraorbital nerve. Although there was no lesion associated with the ectopic canine in the maxillary sinus, the extraction of the tooth led to the resolution of the headache and facial pain.

Power of computed-tomography-defined sarcopenia for prediction of morbidity after pancreaticoduodenectomy

BackgroundThe goal of our study was to evaluate the current approach in prediction of postoperative major complications after pancreaticoduodenectomy (PD), especially symptomatic pancreatic fistula (POPF), using parameters derived from computed tomography (CT).MethodsPatients after PD were prospectively collected in a database of the local department of surgery and all patients with CT scans available were assessed in this study. CT parameters were measured at the level of the intervertebral disc L3/L4 and consisted of the areas of the visceral adipose tissue (AVAT), the diameters of the pancreatic parenchyma (DPP) and the pancreatic duct (DPD), the areas of ventral abdominal wall muscle (AMVEN), psoas muscle (AMPSO), paraspinal muscle (AMSPI), total muscle (AMTOT), as well as the mean muscle attenuation (MA) and skeletal muscle index (SMI). Mann-Whitney-U Test for two independent samples and binary logistic regression were used for statistical analysis.ResultsOne hundred thirty-nine patients (55 females, 84 males) were included. DPD was 2.9 mm (Range 0.7–10.7) on median and more narrow in patients with complications equal to or greater stadium IIIb (p < 0.04) and severe POPF (p < 0.01). DPP median value was 17 (6.9–37.9) mm and there was no significant difference regarding major complications or POPF. AVAT showed a median value of 127.5 (14.5–473.0) cm2 and was significantly larger in patients with POPF (p < 0.01), but not in cases of major complications (p < 0.06). AMPSO, AMSPI, AMVEN and AMTOT showed no significant differences between major complications and POPF. MA was both lower in groups with major complications (p < 0.01) and POPF (p < 0.01). SMI failed to differentiate between patients with or without major complications or POPF.ConclusionBesides the known factors visceral obesity and narrowness of the pancreatic duct, the mean muscle attenuation can easily be examined on routine preoperative CT scans and seems to be promising parameter to predict postoperative complications and POPF.

Adipose Tissue Distribution and Survival Among Women with Nonmetastatic Breast Cancer.

OBJECTIVE:Previous studies of breast cancer survival have not considered specific depots of adipose tissue such as subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT).METHODS:We assessed these relationships among 3,235 women with stage II/III breast cancer diagnosed between 2005–2013 at Kaiser Permanente Northern California and 2000–2012 at the Dana Farber Cancer Institute. SAT and VAT areas (cm2) were calculated from routine CT scans within 6 (median: 1.2) months of diagnosis, covariates were collected from electronic health records, and vital status was assessed by death records. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression.RESULTS:SAT and VAT ranged from 19.0–891 cm2 and 0.484–454 cm2, respectively. SAT was related to increased risk of death [127 cm2 increase, HR (95% CI): 1.13 (1.02, 1.26)] but no relationship with VAT [78.18 cm2 increase: 1.02 (0.91, 1.14)]. An association with VAT was noted among women with stage II cancer [stage II: 1.17 (0.99, 1.39); stage III: 0.90 (0.76, 1.07); p-interaction: <0.01]. Joint increases in SAT and VAT were associated with mortality above either alone [simultaneous 1-SD increase: 1.19 (1.05, 1.34)].CONCLUSIONS:SAT may be an underappreciated risk factor for breast cancer-related death.

Cost-Effectiveness of Biomarker Screening for Traumatic Brain Injury.

Intracranial hemorrhage after traumatic brain injury (TBI) can be life threatening and requires prompt diagnosis. Computed tomography (CT) scans are a rapid and accurate way to evaluate for hemorrhage. In patients with mild and moderate TBI, however, in whom the incidence of intracranial pathology is low, scanning every patient with CT can be costly. The Food and Drug Administration recently approved a novel biomarker screen, the Banyan Trauma Indicator (BTI), to help streamline the decision for CT scanning in mild to moderate TBI. The BTI screen diagnoses intracranial lesions with a sensitivity and specificity of 97.5% and 99.6%, respectively. We performed cost analyses of the BTI screen to determine the threshold of cost-effectiveness, compared with application of clinical decision rules or routine CT scans, for cases of mild or moderate TBI. With a 0.104 probability of an intracranial lesion in mild TBI, the biomarker screen is cost-effective if the cost is $308.96 or below per test. In moderate TBI, because of the greater prevalence of intracranial lesions at 0.663, there is a lower need for screening, and BTI becomes cost-effective up to $73.41 per test.

Impact and cost of preoperative computed tomography imaging on the management of patients diagnosed with high-grade endometrial cancer.

To investigate the cost and impact of routine preoperative computed tomography (CT) in patients with high-grade endometrial cancer, and its role in identifying extrauterine disease. We retrospectively identified patients with high-grade endometrial cancer who underwent routine CT scan prior to surgical procedure between September 1, 2005, and January 31, 2015. Cases in which CT findings led to alterations in the treatment plan were documented. Incidental findings unrelated to endometrial cancer diagnosis were captured. Cost of imaging and diagnostic procedures was based on Ontario's Physician Services-Schedule of Benefits. Of 179 patients included, 57 (31.9%) were diagnosed with stage 3-4 disease. CT showed evidence of metastatic disease in 30 (16.8%) patients; however, planned surgical procedure was altered in only nine (5.0%) cases. CT results showed incidental findings requiring follow-up in 78 (43.6%) cases, three of which were second malignancies. We estimate an expenditure of CAD$14185.85 on routine imaging for every case in which surgical management was changed. Preoperative CT imaging is efficacious in identifying extrauterine disease in patients with high-grade endometrial cancer, although it seldom alters surgical management. Many of these CT scans will identify incidental findings requiring further interventions, resulting in substantial costs.

Magnetic Resonance Imaging-guided Stereotactic Biopsy: A Review of 83 Cases with Outcomes.

Background:The purpose of this study was to determine the relationship between the radiological and histopathological distribution of the cerebral lesions diagnosed with stereotactic biopsy (STB) procedure and its outcomes.Materials and Methods:In the current study, a retrospective analysis of 83 patients that underwent the STB in our clinic from January 2011 to December 2015 was made. T1-weighted contrast-enhanced cranial magnetic resonance imaging examinations were performed on patients on whom Leksell stereotactic frame system was installed. The histopathological and the radiological data derived from the STB procedure were classified.Results:In terms of localization, glial tumor (56.6%) was the most common lesion in all regions, except for the multifocal lesions. Contrary to the common knowledge, lymphoma (14.4%) was found to be the most common lesion among multifocal lesions. The success of obtaining positive STB samples in the current series was 95.2% and the complication rate was 3.6%.Conclusion:Had a routine computed tomography scan been performed on each patient in this series, the number of clinically insignificant small intracerebral hematomas would have probably been higher. Nevertheless, the rate of the STB sampling accuracy and the complication rate were similar to those reported in the relevant literature.

Early detection of lower GI tract tumors by dedicated assessment of the colon on routine computed tomography (CT) imaging: An observational study.

510 Background: We have previously reported that up to 48% of the early features of colorectal cancer (subtle wall thickening, pericolonic stranding, and small lymph nodes in the draining nodal station) were not identified on the original CT abdomen and pelvis (CTAP) reports. This resulted in a 36% decrease in five-year survival based on historical data. In this report, we assessed whether dedicated assessment of the colon on routine CT scans could lead to early detection of colorectal cancer. Methods: 210 CTAPs over a three-month period were screened from the emergency room records at a tertiary care hospital. 194 scans met eligibility. Exclusion criteria included: cases known to the evaluating radiologist and age ≤ 19 or &gt; 89 years. No study was excluded for suboptimal image quality. The original report was reviewed for abnormalities involving the colon, mesentery and bowel and was recorded. A blinded evaluation of the eligible case was then performed by a board-certified radiologist with attention specifically to the colon and the mesentery for the suspicious early features of CRC. The concordance and discordance was then tabulated. Discordant findings were re-evaluated to determine if the discordance was true. Results: 72/194 patients were male, median age 44.5 years (range 20 - 89). 55/194 patients (29.1%) included in the study were noted to have suspicious features. 26 had abnormal lymph nodes, 24 had abnormal colonic wall thickening and 16 had pericolonic stranding and/or wall edema. 45/55 studies were truly discordant from the original interpretation. These included one missed colorectal cancer (confirmed), one likely small bowel neuroendocrine tumor (no follow up), and one likely transitional cell carcinoma of the right renal pelvis (no follow up). Conclusions: Dedicated search of the colon and mesentery on CTAP can identify subtle findings, although their true relevance is being evaluated in a larger future study. Our observational data does indicate that there maybe a potential role for a focused evaluation of the colon and mesentery on routine CTAP in an attempt to potentially increase the rate of cancer detection especially in younger low-average risk patients.

Technique, pitfalls, quality, radiation dose and findings of dynamic 4-dimensional computed tomography for airway imaging in infants and children

This retrospective review of 33 children’s dynamic 4-dimensional (4-D) computed tomography (CT) images of the airways, performed using volume scanning on a 320-detector array without anaesthesia (free-breathing) and 1.4-s continuous scanning, was undertaken to report technique, pitfalls, quality, radiation doses and findings. Tracheobronchomalacia (airway diameter collapse >28%) was recorded. Age-matched routine chest CT scans and bronchograms acted as benchmarks for comparing effective dose. Pitfalls included failure to administer intravenous contrast, pull back endotracheal tubes and/or remove nasogastric tubes. Twenty-two studies (67%) were diagnostic. Motion artefact was present in 16 (48%). Mean effective dose: dynamic 4-D CT 1.0 mSv; routine CT chest, 1.0 mSv, and bronchograms, 1.4 mSv. Dynamic 4-D CT showed tracheobronchomalacia in 20 patients (61%) and cardiovascular abnormalities in 12 (36%). Fourteen children (70%) with tracheobronchomalacia were managed successfully by optimising conservative management, 5 (25%) underwent surgical interventions and 1 (5%) died from the presenting disorder.

Evaluation of the Effect of a Tracheal Stent on Radiation Dose Distribution via Micro-CT Imaging.

Purpose:To study the effect of a metal tracheal stent on radiation dose distribution.Method:A metal tube bracket is placed in a self-made foam tube sleeve, and micro-computed tomography scanning is performed directly. The foam sleeve containing the metal bracket is placed in a nonuniform phantom for a routine computed tomography scan. The stents in conventional computed tomography images are replaced by the stents in micro-computed tomography images. Subsequently, 2 sets of computed tomography images are obtained and then imported to a radiotherapy treatment planning system. A single photon beam at 0° is designed in a field size of 10 cm × 10 cm, a photon beam of 6 MV, and a monitor unit of 200 MU. Monte Carlo algorithm is used to calculate the dose distribution and obtain the dose curve of the central axis of the field. The dose is verified with thermoluminescence dose tablets.Results:The micro-computed tomography images of the tracheal stent are clearer and less false-like than its conventional computed tomography images. The planned dose curves of the 2 groups are similar. In comparison with the images without any stents in place, the doses at the incident surface of the stent in the conventional computed tomography images and at the stent exit surface in the rear of the stent increase by 1.86% and 2.76%, respectively. In the micro-computed tomography images, the doses at the incident surface of the stent and at the exit surface behind the stent increase by 1.32% and 1.19%, respectively. Conventional computed tomography reveals a large deviation between the measured and calculated values.Conclusion:Tracheal stent based on micro-computed tomography imaging has a less effect on radiotherapy calculation than that based on conventional computed tomography imaging.

Routine Postoperative Computed Tomography Is Not Helpful After Elective Craniotomy

Next-day postoperative computed tomography (CT) has been routinely used to obtain radiographic "clearance" for transferring patients after elective craniotomy out of the intensive care unit. The value of this traditional policy, however, has repeatedly been questioned. However, the limited patient numbers might have underestimated the very rare, but catastrophic, events. Therefore, we analyzed the value of routine postoperative CT in a larger cohort of elective tumor, epilepsy, and vascular cases. All the patients who had undergone elective craniotomy were included in our study. The routine postoperative CT scans were analyzed by a neuroradiologist who was unaware of the clinical data. The medical records were retrospectively reviewed for events of arterial hypertension and clinical deterioration. The data from 660 patients with tumors (n= 393; 59.5%), aneurysms (n= 107; 16.2%), and skull base lesions were evaluated. In nearly one half of the patients (n= 264; 45.8%), CT depicted the presence of blood that was not associated with symptoms. Of the 660 patients, 21 (3.6%) showed a mass effect radiographically, 11 of whom underwent revision surgery. Arterial hypertension was documented in only 8 patients (1.3%) and was related to the revision surgery (P= 0.018). The overall revision rate was 2.7% (n= 18). All patients who had undergone revision for postoperative hematoma had presented with a new neurological deficit immediately before CT. Routine postoperative CT did not reveal 1 patient with a serious hematoma that would not have been identified by clinical examination. Patients could be transferred safely from the intensive care unit, if the weaning process and clinical observation findings were uneventful, without deterioration of neurological symptoms or consciousness.

Orthopedic metallic hardware in routine abdomino-pelvic CT scans: occurrence and clinical significance

To study the occurrence of orthopedic metallic hardware in routine abdomen/pelvic computed tomography (CT) scans and their impact on image quality (IQ) and diagnostic evaluation. In this retrospective single institution study, we analyzed 3500 consecutive abdomen/pelvis CT scans for occurrence of orthopedic metallic hardware. In the cohort of patients with metallic hardware detected on CT scans, subjective and objective IQ analysis was performed to estimate diagnostic acceptability (DA, 4-point scale), subjective noise (SN, 3-point scale), presence of artifacts (PA, 4-point scale) and objective noise. The clinical significance of metallic hardware was determined by evaluating the impact of artifacts on radiological diagnosis according to the clinical indication and disease type. Orthopedic metallic hardware was encountered in 4.97% of abdomino-pelvic CT scans (n=174/3500), and artifacts related to the hardware in the region of clinical interest were identified in 82% (n=144/174) of scans. The overall mean DA was 2.66 (n=174), and it was severely limited (score<2) in 32% of cases particularly affecting patients with bilateral hip implants (92.6%, n=25/27). The artifacts due to hardware significantly limited diagnostic evaluation in 58.6% of cases (PA score≥3), and the image noise was unacceptable in 71% of cases (SN score>2) in the region of clinical interest. Orthopedic metallic hardware is encountered in nearly 5% of abdomino-pelvic CT scans and causes significant image degradation limiting diagnostic evaluation in the region of clinical interest.