Introduction: Metal artefacts seriously degrade the quality of the CT images. Blurring around the junctions between metal and non-metal regions in CT images, metal artefacts often prevent right diagnoses, and even lead to misdiagnoses of patients. The aim of the study was to devise a fast and robust method to improve the quality of the artefact-contaminated CT images.
Methods: The proposed artefact correction includes the following five steps: metal object segmentation, forward projection, region-based filling, adaptive scaling and final image reconstruction.
Results: The feasibility of the proposed method in correcting metal artefacts was validated by experiments on both simulated and clinical images. Experiments showed the proposed correction could lead to fast and effective reduction of metal artefacts in CT images.
Conclusions: Compared with other methods, the proposed method has less computational cost and allows a feasible and easy implantation into current CT imaging systems.
Introduction: The aims of this study were to determine the diagnostic value of MR urography and to compare the T2- and T1-weighted MR urography techniques in patients with urinary diversion.
Methods: We retrospectively reviewed 19 MR urograms in 14 patients (13 male and one female, 8–77 years old, mean age: 54.2) with urinary diversion. Magnetic resonance urography examinations were performed with 1.5-T MR scanners. In addition to T2- and T1-weighted MR urography techniques, conventional T1- and T2-weighted axial and coronal sequences were also obtained. Collecting systems were evaluated in five segments (right proximal and distal collecting system, left proximal and distal collecting system and conduit or reservoir). Imaging features of the urinary collecting systems were evaluated with T2- and T1-weighted MR urography images. The clinical, laboratory data and follow-up imaging findings were regarded as standard. A cross table was formed to determine sensitivity, specificity and accuracy of MR urography techniques.
Results: T2-weighted MR urography, T1-weighted MR urography and combination of these two techniques could demonstrate 89.01, 87.65 and 93.83% of all collecting system segments, respectively. For the detection of the pathologic urinary segments, sensitivity, specificity and accuracy were 100, 95.29 and 95.6% in T2-weighted MR urography and 100, 93.42 and 93.82% in T1-weighted MR urography, respectively. Sensitivity, specificity and accuracy were 100% in combined T2- and T1-weighted MR urography technique.
Conclusion: Magnetic resonance urography is an effective imaging method for the evaluation of the urinary system in patients with urinary diversion. T2-weighted MR urography alone has high sensitivity, specificity and accuracy, does not require intravenous contrast medium and can be obtained in 3–5 min. However, T1-weighted MR urography may provide additional information in some cases.
Objective: To evaluate the significance of oesophageal dilatation on high-resolution CT (HRCT) chest in patients with systemic sclerosis.
Methods: We retrospectively retrieved the database of patients with systemic sclerosis seen at our hospital between January 2008 and January 2009. A total of 50 patients (46 women and four men) who had HRCT chest, pulmonary function testing and echocardiography within 1 month were included in the study. Peak pulmonary artery (PA) pressures and pulmonary function testing were charted. The HRCT chest was interpreted by a chest radiologist. Oesophageal dilatation was defined as a luminal coronal diameter of ≥9 mm in infra-aortic oesophagus. Extent of ground glass, reticulation and honeycombing was objectively scored.
Results: Statistical analysis using independent t-test showed that diffusion capacity of carbon monoxide was significantly lower (P = 0.042) and peak PA pressures were significantly higher (P = 0.045) in patients with oesophageal dilatation (n = 29) as compared with those without oesophageal dilatation (n = 21). The two cohorts had no significant difference in their total lung capacity and HRCT determined extent of interstitial lung disease.
Conclusion: Patients with oesophageal dilatation on HRCT chest had significantly lower diffusion capacity of carbon monoxide and higher peak PA pressures, which suggest that these patients tend to have more severe pulmonary vascular disease.
Introduction: This study aimed to evaluate the diagnostic value of dual time point imaging (DTPI) of 18F-fluorodeoxyglucose (FDG) positron emission tomography/CT (PET/CT) for detecting the infective lesions in patients with extrapulmonary tuberculosis (EPTB).
Methods: Eleven patients were consecutively recruited and evaluated. After the intravenous injection of 369 ± 153 MBq of FDG, all patients underwent FDG PET/CT imaging at two different time points: early scan at 57 ± 23 min and delayed scan at 136 ± 42 min. The maximum standardized uptake values (SUVmax) were recorded for both time points (early scan: SUVmax1 and delayed scan: SUVmax2).
Results: In total, 30 lesions were detected. The SUVmax2 in 22 of the lesions in confirmed EPTB patients were significantly higher than the SUVmax1 (7.9 ± 3.2 vs. 6.8 ± 2.5; P = 0.001). The SUVmax for another eight non-EPTB lesions also showed a significant increasing pattern of change (6.2 ± 2.6 vs. 6.5 ± 2.8; P = 0.044). However, there was insignificant difference between the mean percentage difference of SUVmax (%ΔSUVmax) of EPTB and non-EPTB lesions (P = 0.06).
Conclusion: Our study demonstrates that early whole body PET/CT imaging may be sufficient for the detection of the EPTB lesions and DTPI of PET/CT may also not be a useful technique in differentiating between EPTB and non-EPTB lesions. However, our findings are based on a limited number of patients, and therefore, further investigations in larger series of patients are warranted.
Purpose: Tuberculous meningitis (TBM) is associated with borderzone necrosis (BZN) of the brain parenchyma in areas adjacent to meningeal inflammation. Diffusion-weighted MRI (DWI) allows for accurate detection of cytotoxic oedema associated with necrosis. Detection and characterisation of BZN using DWI to explain its pathogenesis in TBM have not been performed previously in children. Our objective was to identify the prevalence and characteristics of BZN using DWI in children with TBM and to correlate it with the presence, degree and distribution of basal meningeal enhancement (BE) in the absence of large-vessel thrombosis.
Methods: A retrospective descriptive MRI DWI study of 34 children with TBM was conducted. The topography of BZN was compared with the presence and severity of BE on specific MRI sequences.
Results: BZN was identified on MRI DWI in 50% of patients of which 82% had involvement of the temporal lobes. The severity and extent of BE in either middle cerebral artery cistern correlated with the presence of BZN (P = 0.02). BZN did not correlate with radiologically detectable vascular occlusion.
Conclusion: BZN is common in TBM occurring in 50% of children. Detection and confirmation of cytotoxic oedema associated with BZN using DWI, and its clear relation to BE supports existing pathogenetic descriptions. The pathogenesis of BZN differs to that of topographical infarction on the basis of distribution as well as an absent statistical relationship between vascular occlusion and BZN.
Simultaneous pancreatic-kidney transplantation is the definitive treatment for patients with type 1 diabetes mellitus and renal failure. Pancreatic graft failure is an important postoperative complication and most commonly occurs as a result of pancreatitis, graft thrombosis or rejection. Distinguishing between these causes is necessary to determine timely, appropriate management and thereby potentially minimising graft loss. Multi-detector CT imaging may be used to identify the cause of pancreatic graft dysfunction when renal function is not markedly impaired.
BreastScreen Australia provides free mammographic screening for asymptomatic women over the age of 40, targeting women aged 50–69. Occasionally women will present to screening programmes with a history of nipple discharge, which is uncommonly associated with significant underlying breast disease. Seventy-six women with a history of nipple discharge were recalled to BreastScreen Western Australia assessment centres from 2004 to 2008, of whom 72 were recalled primarily for their symptoms. Thirty-six of these patients had pathology investigations, including 18 nipple discharge smears, 17 fine needle aspirations, 11 core biopsies and eight surgical biopsies or therapeutic resections. The biopsies found 11 intraduct papillomas and one invasive ductal carcinoma with ductal carcinoma in situ. Fourteen patients had imaging findings consistent with benign mammary duct ectasia. Our findings confirm that the presentation of nipple discharge in a screening programme is uncommonly associated with significant breast disease, and present representative cases of the radiological findings with pathological correlation of benign and malignant causes including mammary duct ectasia, intraduct papillomas, multiple papillomas, invasive ductal carcinoma and ductal carcinoma in situ.
Introduction: Distinction between postoperative recurrent glioma and radiation injury remains a tough diagnostic problem for routine imaging methods. The purpose of this study is to evaluate the differentiated effectiveness of perfusion weighted imaging (PWI) for the two entities.
Methods: PWI was performed using Siemens 3.0-T MR system for 35 patients with new contrast-enhancing lesions at the site of treated glioma. Regions of interest (ROIs) were manually drawn at the contrast-enhancing lesion and peri-lesion edema areas. For calculation of standardised relative cerebral blood volume (rCBV) ratios, the same size ROIs were drawn at the area of contralateral hemisphere normal white matter on rCBV maps. At least five ROIs were selected at each lesion. The rCBV values were measured and the rCBV ratios were calculated. The maximum rCBV (rCBVmax) ratio at each region was chosen for analysis. The patients were divided into two groups: tumour recurrence and radiation injury. The mean rCBVmax ratios were compared between the two groups.
Results: The mean rCBVmax ratio in the contrast-enhancing lesion was significantly higher in the tumour recurrence (4.36 ± 1.98) compared with that (1.28 ± 0.64) in the radiation injury (P < 0.01). The mean rCBVmax ratio in the peri-lesion edema was also significantly higher in the tumour recurrence (1.79 ± 0.51) compared with that (0.85 ± 0.28) in the radiation injury (P < 0.05). A recurrent tumour was suggested when the rCBVmax ratio >2.15 based on the receiver operating characteristic curve. Four patients with recurrent tumour and three with radiation injury were misclassified.
Conclusion: PWI is a useful method to distinguish tumour recurrence and radiation injury.
Introduction: The use of conservative surgery combined with whole-breast irradiation (WBI) has been established as a valid alternative to mastectomy for the management of early-stage breast cancer. The aim of this study was to compare dosimetric parameters of the planning target volume(PTV) and organs at risk (OARs) between conventional radiation therapy (CR), 3-D conformal radiation therapy (3DCRT), and direct machine parameter optimisation intensity-modulated radiation therapy (DMPO-IMRT) after breast-conserving surgery.
Methods and Materials: Computed tomography (CT) scans from 20 patients (13 left-sided and 7 right-sided) previously treated with T1N0 or ductal carcinoma were selected for this dosimetric planning study. We designed CR, 3DCRT and DMPO-IMRT plans for each patient. The prescribed dose was 50 Gy/2 Gy/25 f, 95% of PTV received the prescription dose. Doses were computed with a commercially available treatment planning system using convolution/superimposition (CS) algorithm. Plans were compared according to dose-volume histogram (DVH) analysis in terms of PTV homogeneity and conformity indices (HI and CI) as well as OARs dose and volume parameters.
Results: Both the HI and CI of the PTV showed statistically significant difference between CR, 3DCRT and DMPO-IMRT with those of DMPO-IMRT were best (P < 0.05). Compared with CR, 3DCRT showed smaller exposed volumes of ipsilateral lung, contralateral breast and heart while DMPO-IMRT indicated larger exposed volumes of ipsilateral lung (except for V20 and V30), contralateral breast and heart. In addition, DMPO-IMRT demonstrated an increase of exposed volume of ipsilateral lung (except for V30), contralateral breast and heart compared with 3DCRT.
Conclusions: In WBI of breast cancer after conservative surgery, 3DCRT and DMPO-IMRT improved the homogeneity and conformity of the PTV compared with CR. Meanwhile, 3DCRT reduced the irradiated volumes of OARs at all dose levels listed in our study while DMPO-IMRT reduced the irradiated volumes of OARs in high-dose areas but increased the irradiated volumes of OARs in low-dose areas.
Introduction: To evaluate the incidence and impact of early post-chemoradiation (cRT) ‘pseudoprogression’ (PsPD) amongst glioblastoma multiforme (GBM) patients treated with the current standard of care – 60 Gy conformal radiotherapy with concurrent low-dose temozolomide, followed by six cycles of high-dose temozolomide (the ‘Stupp protocol’).
Methods: Clinical notes and radiology reports for GBM patients treated as per the Stupp protocol were reviewed. PsPD was defined as apparent radiological progression on the first post-cRT scan, with further imaging within 3 months being stable or improving, while true early progression (ePD) was confirmed by continued progression in the subsequent 3 months following the first post-cRT scan.
Results: Of the 68 patients evaluated, 14 (21%) and 27 (40%) experienced PsPD and ePD, respectively; 3/14 (21%) patients experiencing PsPD and 14/27(52%), ePD were symptomatic for progression on first post-cRT follow-up (P = 0.096 for difference). Median survival for patients with ePD, PsPD and neither were 10.4, 27.4 and 13.0 months, respectively (P = 0.003 for ePD vs. PsPD, P = 0.19 for neither vs. PsPD groups).
Conclusion: These data confirm a significant incidence of PsPD in post-cRT GBM patients, associated with improved median survival compared with those with neither ePD nor PsPD (not statistically significant). It appears likely that PsPD actually represents tumour response, conflicting with the traditional notion that increase in lesion size on contrast-enhanced imaging represents disease progression. Early post-cRT imaging should thus be interpreted with caution. Accompanying clinical symptoms are more commonly associated with ePD, but do not reliably distinguish PsPD from ePD.
Purpose: Volumetric-modulated arc therapy (VMAT) is a relatively new treatment technique in radiation therapy. A comparison study of conformal, intensity-modulated radiation therapy (IMRT) and single- and double-arc VMAT plans was undertaken to evaluate the dosimetric impact of this new technology in prostate cases. The research questions were as follows: how does VMAT dosimetry compare with IMRT and conformal plans?; does VMAT increase the volume of bowel receiving lower doses?; are one or two VMAT arcs required for standard prostate cases?
Methods: Eight prostate cancer and post-prostatectomy patients were randomly selected for this study. Conformal, IMRT and single and double Arc VMAT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 75.6 Gy over a course of 42 fractions to the planning target volume (PTV).
Results: The Healthy Tissue Conformity Index and the conformation number results revealed the IMRT and two VMAT techniques to have superior dosimetry to the PTV compared with the conformal plans. The maximum dose delivered to the PTV was significantly higher with the single-arc VMAT technique compared with the conformal or double-arc VMAT plans. There were no significant differences between the planning techniques for the bladder and small bowel dosimetry. However, IMRT and VMAT plans delivered less radiation to the rectum and femoral heads, and a single-arc VMAT plan was optimal for the right femoral head and the two VMAT techniques were optimal to the IMRT plans for the left femoral head.
Conclusions: Single- and double-arc VMAT consistently resulted in favourable or slightly superior dosimetry when compared with static gantry IMRT for prostate cases. Both the VMAT techniques and static gantry IMRT resulted in superior critical tissue sparing when compared with conformal plans.
Introduction: This paper outlines the key results of the Faculty of Radiation Oncology 2010 workforce survey and compares these results with earlier data.
Methods: The workforce survey was conducted in mid-2010 using a custom-designed 17-question survey. The overall response rate was 76%.
Results: The majority of radiation oncologist respondents were male (n = 212, 71%), but the majority of trainee respondents were female (n = 59, 52.7%). The age range of fellows was 32–92 years (median: 47 years; mean: 49 years) and that of trainees was 27–44 years (median: 31 years; mean: 31.7 years). Most radiation oncologists worked at more than one practice (average: two practices). The majority of radiation oncologists worked in the public sector (n = 169, 64.5%), with some working in ‘combination’ of public and private sectors (n = 65, 24.8%) and a minority working in the private sector only (n = 28, 10.7%). The hours worked per week ranged from 1 to 85 (mean: 44 h; median: 45 h) for radiation oncologists, while for trainees the range was 16–90 (mean: 47 h; median: 45 h). The number of new cases seen in a year ranged from 1 to 1100 (mean: 275; median: 250). Most radiation oncologists considered themselves generalists with a preferred sub-specialty (43.3%) or specialists (41.9%), while a minority considered themselves as generalists (14.8%).
Conclusions: There are a relatively large and increasing number of radiation oncologists and trainees compared with previous years. The excessive workloads evident in previous surveys appear to have diminished. However, further work is required on assessing the impact of ongoing feminisation and sub-specialisation.
To develop and assess a method of palliative radiotherapy utilising a kilovoltage imaging system incorporated with a linear accelerator. The conventionally separate procedures of simulation, planning and treatment were merged into a single appointment on a linear accelerator. The process was tested using a humanoid phantom and hypothetical treatment scenarios. A clinical investigation was then undertaken for patients requiring palliative radiotherapy. A total of 10 treatment sites were simulated, planned and treated using the online approach. Each step was timed for both the phantom and patient treatments and was compared with a simulation process involving a separate appointment on a conventional simulator. The contrast and resolution achievable with the linear accelerator-based imaging system was found to be comparable with a conventional simulator. Bony anatomy was plainly visible and suitable for target definition. The mean total treatment time for the humanoid phantom (n = 5) was 21.4 ± 0.9 (standard error) mins. The mean total treatment time for actual patients (n = 10) was 25.7 ± 1.6 mins (the mean simulation, planning and treatment times were 11.0 ± 0.5 mins, 14.5 ± 1.0 mins and 3.6 ± 0.2 mins, respectively). This study demonstrated that palliative radiotherapy treatments can be simulated, planned and treated in a single cohesive patient appointment, using an online approach that is technically comparable with the conventional simulation method. This approach has the potential to expedite palliative radiotherapy service delivery and reduce resource burdens by minimising the number of patient appointments and wait times between appointments.