Radiology - Research Publications
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ItemA pilot study investigating the role of 18F-FDG-PET in the early identification of chemoradiotherapy response in anal cancer(WILEY, 2022-12)INTRODUCTION: Anal cancer (AC) is 18 F-FDG-PET avid and has been used to evaluate treatment response several months after chemoradiotherapy. This pilot study aimed to assess the utility of semi-automated contouring methods and quantitative measures of treatment response using 18 F-FDG-PET imaging at the early time point of 1-month post-chemoradiotherapy. METHODS: Eleven patients with AC referred for chemoradiotherapy were prospectively enrolled into this study, with 10 meeting eligibility requirements. 18 F-FDG-PET imaging was obtained pre-chemoradiotherapy (TP1), and then 1-month (TP2), 3-6 months (TP3) and 9-12 months (TP4) post-chemoradiotherapy. Manual and semi-automated (Threshold) contouring methods were used to define the primary tumour on all 18 F-FDG-PET images. Resultant contours from each method were interrogated using quantitative measures, including volume, response index (RI), total lesion glycolysis (TLG), SUVmax , SUVmedian and SUVmean . Response was assessed quantitatively as reductions in these measures and also qualitatively against established criteria. RESULTS: Nine patients were qualitatively classified as complete metabolic responders at TP2 and all 10 at TP3. All quantitative measures demonstrated significant (P < 0.05) reductions at TP2 for both Manual and Threshold methods. All reduced further at TP3 and again at TP4 for Threshold methods. TLG showed the highest reduction at all post-chemoradiotherapy time points and classified the most responders for each method at each time point. All patients are recurrence-free at minimum 4-year follow-up. CONCLUSION: Based on our small sample size, semi-automated methods of disease definition using 18 F-FDG-PET imaging are feasible and appear to facilitate quantitative response classification of AC as early as 1-month post-chemoradiotherapy. Early identification of treatment response may potentially improve disease management.
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ItemDefining primary anal cancer tumour volume on FDG–PET – an initial assessment of semi–automated methods(MedCrave Group, LLC, 2021-01-12)Purpose Clinician inexperience, intra–observer and inter–observer variations in tumour definition may affect staging, radiotherapy target definition, and treatment outcomes, particularly in rare cancers. The purpose of this study was to assess the correlation between semi–automated methods of primary anal cancer (AC) definition and our current clinical standard of manual clinician definition using 18F–FDG–PET imaging and to provide recommendations for clinical use. Methods All patients referred for chemoradiotherapy for AC between 2012 and 2016 were prospectively enrolled, with all 18F–FDG–PET imaging acquired within one year of chemoradiotherapy collected. Three methods of primary AC definition were performed on all PET datasets. Manual definition by an experienced radiologist was considered the clinical standard for comparison of volume and coincidence (Dice coefficient) in our study. Semi–automated techniques assessed included a gradient–based SUV (SUV–gradient) method and a SUV threshold method with a range of thresholds relative to SUVmax (40 (T40), 50 (T50) and 60% (T60)). Results Ten patients were enrolled with 33 PET study sets available for analysis. While all methods created contours on pre– and post–treatment scans, manual definition of PET–avid disease was only necessary on 11 of the 33 study sets. SUV–gradient and T40 defined contours were not statistically different in volume to the clinical standard (p = 0.83 & 0.72 respectively). The observed Dice coefficient relative to the manual clinician contours were 0.75 and 0.73 for the SUV–gradient and T40 methods respectively. Conclusions It is possible to define gross AC using SUV–based methods, with the SUV–gradient–based method followed by the T40 method most closely correlating with our current clinical standard. The SUV–gradient–based method studied is housed within a proprietary clinical system. A semi–automated approach that uses a vendor neutral T40 method and the clinician’s knowledge and skill appears optimal in defining AC. With this approach AC may be defined reliably to enhance efficiencies in radiotherapy and nuclear medicine processes, and to support clinicians in identifying and defining this rare disease. Trial registration ANZCTR, ACTRN12620000066987. Registered 28 January 2020–Retrospectively registered, https://www.anzctr.org.au/ACTRN12620000066987.aspx
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ItemAvid F-FDG uptake of pectoralis major muscle: an equivocal sequela of strenuous physical exercise.(Department of Biomedical Imaging, University of Malaya, Malaysia, 2009-04)Avid functional (18)F-FDG uptake of skeletal muscle is a known false positive finding of PET-CT study especially after involuntary muscle exercise just prior to the study. We describe the case of a 50-year-old man in whom the finding of avid (18)F-FDG uptake of pectoralis major muscle was encountered during investigation of metastatic melanoma.
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ItemSignificance of subcentimetre F-FDG PET/CT pulmonary abnormality in patients with known extrapulmonary malignancy.(Department of Biomedical Imaging, University of Malaya, Malaysia, 2010)
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ItemAn intense F-FDG pulmonary microfocus on PET without detectable abnormality on CT: A manifestation of an iatrogenic FDG pulmonary embolus.(Department of Biomedical Imaging, University of Malaya, Malaysia, 2010)An incidental finding of an intense focus of (18)F-Fluorodeoxyglucose (FDG) pulmonary uptake on positron emission tomography (PET) without detectable lesions on computed tomography (CT) is highly suggestive of FDG microembolus. Its microscopic nature means it is undetectable on CT. It is an artefact attributable to (18)F-FDG-tracer contamination at the injection site. This paper reports a case of a 61 year-old lady with a past history of breast carcinoma, in whom follow-up PET/CT images demonstrated an incidental intense FDG pulmonary abnormality. A follow-up PET/CT seven months later demonstrated complete resolution of the abnormality.
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ItemThe clinical utility of fluorodeoxyglucose-positron emission tomography for investigation of fever in immunocompromised children(WILEY, 2018-05)AIM: Fever in immunocompromised children presents significant challenges. We aimed to determine the clinical impact of fluorodeoxyglucose-positron emission tomography (FDG-PET) in combination with computed tomography (CT) in children with malignancy or following haematopoietic stem cell transplantation with prolonged or recurrent fever. METHODS: Immunocompromised children who underwent FDG-PET/CT for investigation of prolonged or recurrent fever were identified from hospital databases. The clinical impact of the FDG-PET/CT was considered 'high' if it contributed to any of the following: diagnosis of a new site infection/inflammation, change to antimicrobials or chemotherapy, or additional investigations or specialist consult contributing to final diagnosis. RESULTS: Fourteen patients underwent an FDG-PET/CT for prolonged or recurrent fever. Median age was 11 years and 46% had diagnosis of acute lymphoblastic leukaemia. The median absolute neutrophil count on the day of FDG-PET/CT was 0.47 cells/μL. The clinical impact of FDG-PET/CT was 'high' in 11 (79%) patients, contributing to rationalisation of antimicrobials in three, and cessation of antimicrobials in five. Compared to conventional imaging, FDG PET/CT identified seven additional sites of clinically significant infection/inflammation in seven patients. Of the 10 patients who had a cause of fever identified, FDG-PET/CT contributed to the final diagnosis in six (60%). CONCLUSION: This study has identified potential utility for FDG-PET/CT in immunocompromised children with prolonged or recurrent fever. Further prospective studies are needed to compare FDG-PET/CT versus conventional imaging, to identify the optimal timing of FDG-PET/CT and to study the role of subsequent scans to monitor response to therapy.
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ItemPET/CT findings within the contralateral tonsil following unilateral tonsillectomy(WILEY-BLACKWELL, 2016-11)OBJECTIVES/HYPOTHESIS: In the setting of considerable variation of pharyngeal palatine tonsil fluorine 18 fluorodeoxyglucose (FDG) uptake, we mostly rely on the asymmetry between the left- and right-sided tonsils to identify underlying malignancy. The current study evaluates the FDG positron emission tomography (PET)/computed tomography (CT) findings within the contralateral tonsil among patients who had unilateral tonsillectomy and analyzes the cancer incidence in the contralateral tonsil with high FDG avidity. STUDY DESIGN: A retrospective cohort study in a single high-volume tertiary cancer center. METHODS: Analysis of the PET/CT scans performed at Peter MacCallum Cancer Center (Melbourne, Australia) between June 1, 2005, and December 31, 2014. RESULTS: The study group consists of 160 patients who underwent 308 postunilateral tonsillectomy FDG PET/CT scans. The majority of unilateral tonsillectomies were undertaken for the treatment or diagnosis of oropharyngeal squamous cell carcinoma (85.1%).The mean follow-up time succeeding unilateral tonsillectomy was 38.2 months. Ten (6.25%) patients had relatively high contralateral tonsil FDG uptake (mean maximal standardized uptake value 6.9). Only one patient, with localized high FDG uptake but no other high uptake within the Waldeyer's ring and no previous PET/CT for comparison, underwent contralateral tonsillectomy. This was found to be benign. None of the 160 patients, including those nine patients, had developed contralateral tonsil malignancy at the end of the study period. CONCLUSION: Positron emission tomography/computed tomography remains a reliable surveillance tool within the contralateral tonsil following unilateral tonsillectomy. Comparison with previous PET/CT scans and comparison with other subsites within the Waldeyer's ring, in combination with appropriate follow-up and clinical judgment, facilitate PET/CT high accuracy. LEVEL OF EVIDENCE: 4. Laryngoscope, 126:2480-2483, 2016.
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ItemProstate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT)-guided stereotactic ablative body radiotherapy for oligometastatic prostate cancer: a single-institution experience and review of the published literature(WILEY, 2019-11)OBJECTIVES: To report the outcomes of stereotactic ablative body radiotherapy (SABR) in men with oligometastatic prostate cancer (PCa) diagnosed on prostate-specific membrane antigen (PSMA)-positron emission tomography/computed tomography (PET/CT), based on a single-institution experience and the published literature. PATIENTS AND METHODS: This was a retrospective cohort study of the first 20 consecutive men with oligometastatic PCa, treated with SABR in a single institution, who had biochemical recurrence after previous curative treatment (surgery/radiotherapy), had no evidence of local recurrence, were not on palliative androgen deprivation therapy (ADT), and had PSMA-PET/CT-confirmed oligometastatic disease (≤3 lesions). These men were treated with SABR to a dose of 30 Gy in three fractions for bone metastases, and 35-40 Gy in five fractions for nodal metastases. The outcomes of interest were: PSA response; local progression-free survival (LPFS); distant progression-free survival (DPFS); and ADT-free survival (ADTFS). A literature review was performed to identify published studies reporting on outcomes of PSMA-PET/CT-guided SABR. RESULTS: In our institutional cohort, 12 men (60%) had a decline in PSA post-SABR. One man had local progression 9.6 months post-SABR, with 12-month LPFS of 93%. Ten men had distant progression outside of their SABR treatment field, confirmed on PSMA-PET/CT, with 12-month DPFS of 62%, of whom four were treated with palliative ADT, two received prostate bed radiotherapy for prostate bed progression (confirmed on magnetic resonance imaging), and four received a further course of SABR (of whom one had further progression and was treated with palliative ADT). At last follow-up, six men (one with local progression and five with distant progression) had received palliative ADT. The 12-month ADTFS was 70%. Men with longer intervals between local curative treatment and SABR had better DPFS (P = 0.03) and ADTFS (P = 0.005). Four additional studies reporting on PSMA-PET/CT-guided SABR for oligometastatic PCa were identified and included in the review, giving a total of 346 patients. PSA decline was reported in 60-70% of men post-SABR. The 2-year LPFS, DPFS and ADTFS rates were 76-100%, 27-52%, and 58-62%, respectively. CONCLUSION: Our results showed that PSMA-PET/CT could have an important role in identifying men with true oligometastatic PCa who would benefit the most from metastases-directed therapy with SABR.
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ItemVentilation perfusion lung SPECT/CT in pregnancy during COVID-19(WILEY, 2020-12)
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ItemBreast ultrasound in breast cancer surveillance; incremental cancers found at what cost?(CHURCHILL LIVINGSTONE, 2020-12)PURPOSE: To determine the diagnostic parameters of breast ultrasound (US) in the setting of routine radiological surveillance after a diagnosis of breast cancer and evaluate costs of the inclusion of breast US as well as any survival benefit of US detected cases of recurrence in surveillance. METHODS: 622 patients underwent breast cancer surgery and follow up at Austin Health from July 2009 to December 2015. Retrospective data analysis was performed to determine; diagnostic parameters, financial costs of US and survival outcomes of US detected cases of recurrence. RESULTS: Patients underwent 1-9 years of breast cancer surveillance, with a median of 4.24 years. 390 (62.7%) patients underwent additional breast US surveillance to mammography. 232 (38.3%) fit criteria for use of additional breast US. 199 abnormal imaging episodes occurred, leading to 16 screen detected-cases of locoregional recurrence. US alone generated 107 abnormal images and found 9 cancers. US had a sensitivity of 44.1%, specificity of 95.2% and positive predictive value of 11.7% in comparison to mammography; 20.6%, 97.4% and 9.9% respectively. US had a biopsy rate of 4.0% and lead to an incremental cancer detection rate of 0.38%. The cost of incremental cancer found was $31,463.72 AUD. Survival outcomes based on method of detection of recurrence were insignificant (p value = 0.71). CONCLUSIONS: Breast US has a sensitivity of 44.1% and detected seven recurrences that were mammographically occult. Breast US has a similar PPV to mammography in surveillance. Breast US generated considerable biopsy rates and costs. Survival analysis was not able to detect any benefit of US detected cases of recurrence.