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Technological advancement in computed tomography (CT) and MRI has improved cholesteatoma detection rates considerably in the past decade. Accurately predicting disease location and extension is essential for staging, planning, and preoperative counseling, in particular in the newer approach of endoscopic ear surgery. Improved sensitivity and specificity of these radiological methods may allow the surgeon to confidently monitor patients, therefore avoiding unnecessary surgery. This article outlines recent advances in CT and MRI technology and advantages and disadvantages of the newer techniques. Emphasis on improving the feedback loop between the radiologist and surgeon will increase the accuracy of these new technologies.

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OBJECTIVES: To evaluate the effect of pre-scan blood glucose levels (BGL) on standardized uptake value (SUV) in 18F-FDG-PET scan. METHODS: A literature review was performed in the MEDLINE, Embase, and Cochrane library databases. Multivariate regression analysis was performed on individual datum to investigate the correlation of BGL with SUVmax and SUVmean adjusting for sex, age, body mass index (BMI), diabetes mellitus diagnosis, 18F-FDG injected dose, and time interval. The ANOVA test was done to evaluate differences in SUVmax or SUVmean among five different BGL groups (< 110, 110-125, 125-150, 150-200, and > 200 mg/dl). RESULTS: Individual data for a total of 20,807 SUVmax and SUVmean measurements from 29 studies with 8380 patients was included in the analysis. Increased BGL is significantly correlated with decreased SUVmax and SUVmean in brain (p < 0.001, p < 0.001,) and muscle (p < 0.001, p < 0.001) and increased SUVmax and SUVmean in liver (p = 0.001, p = 0004) and blood pool (p = 0.008, p < 0.001). No significant correlation was found between BGL and SUVmax or SUVmean in tumors. In the ANOVA test, all hyperglycemic groups had significantly lower SUVs compared with the euglycemic group in brain and muscle, and significantly higher SUVs in liver and blood pool. However, in tumors only the hyperglycemic group with BGL of > 200 mg/dl had significantly lower SUVmax. CONCLUSION: If BGL is lower than 200 mg/dl no interventions are needed for lowering BGL, unless the liver is the organ of interest. Future studies are needed to evaluate sensitivity and specificity of FDG-PET scan in diagnosis of malignant lesions in hyperglycemia.

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INTRODUCTION: The need to measure reporting workload in teaching departments remains a current pertinent need. In Australia, the Pitman-Jones reporting RVUs have been in the public domain since 2003 (revised in 2009). These are expressed in arbitrary units. In New Zealand, single-site Christchurch Hospital reporting times have been validated and placed in the public domain. Concurrently, the RANZCR has been developing a formulaic descriptor lexicon for imaging studies (the Body System Framework). There is a need to bring these three strands of work together into a common public resource. In 2015, under the auspices of the Chief Accreditation Officer, RANZCR convened the Radiologist Workload Working Group. The goal of the group was to develop a robust method of measuring radiologist workload in teaching departments in Australia and New Zealand for the RANZCR accreditation processes of teaching departments as training sites. This paper concerns itself with one aspect of the group's work, namely reaching a consensus on radiologist study ascribable times for common imaging studies. METHOD: The BSF examination descriptors were reduced to a smaller, generic dataset of descriptors at the expense of loss of specificity. BSF study ascribable times had been previously obtained by stopwatch observation. The dataset was harmonized with the Christchurch descriptors to ensure commonality of case mix. The two lead authors reached an approximate consensus study ascribable time for each descriptor in agreement with the BSF and Christchurch data. Specifically, the Christchurch reporting times were relied on extensively to validate the new dataset's study ascribable times. The first draft of descriptors and times was tabled at the meetings of the RANZCR Radiologist Workload Working Group, and was progressively refined by iterative consensus. RESULTS: The output of the Radiologist Workload Working Group comprises a simplified modality-based table of robust descriptors and 'best estimate' corresponding study ascribable times. These can be used with the extant Pitman-Jones methodology in order to estimate the reporting workload of a medical imaging teaching department in units of time. As a first for Australia and New Zealand, nuclear medicine and PET study ascribable times have been incorporated and balanced against radiology study ascribable times. CONCLUSION: The RANZCR 2016 study ascribable times are ready for use by the Australian and New Zealand radiologist and nuclear medicine specialist community. We hope these times will also stimulate further data collection in our two countries towards a robust, bi-national study ascribable times database.

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INTRODUCTION: Variations of the renal arteries have been studied and published across various population groups, but similar information for the ethnically diverse nation of Australia is lacking. This study describes the pattern of renal artery anomalies in a section of the Australian population based on computed tomography (CT) angiograms of the abdomen and cadaveric dissection. METHODS: The renal arterial vasculature of 594 kidneys from 300 subjects (28 cadavers, 272 CT) was studied. The number and pattern of renal arteries were categorised on the basis of laterality, point of origin and termination in the kidney (superior pole, hilum and inferior pole), symmetry and sex. RESULTS: Multiple renal arteries were discovered in 22% of subjects and 12.12% of kidneys. The most common pattern observed was the presence of one variant renal artery (93.1%), compared to the finding of two (5.6%) and three (1.4%) multiple arteries. The aorta was the most frequent site of origin for anomalous vessels, while the hilum was the predominant point of entry. No significant difference was established between left- and right-sided kidneys (13.8% vs. 12.5%; P = 0.627); however, unilateral distribution was more common than bilateral additional renal arteries (16.7% vs. 3.4%; P < 0.01), and variations among males were more than females (27.2% vs. 15.2%; P < 0.05). A higher rate of multiple renal arteries was noted in cadaveric dissections compared to CT images (46.4% vs. 19.5%; P < 0.01). CONCLUSION: These findings provide application of an evidence-based teaching tool that facilitates education regarding renal arterial variations in Australia.

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Referral to a clinical radiologist is the prime means of communication between the referrer and the radiologist. Current Australian and New Zealand government regulations do not prescribe what clinical information should be included in a referral. This work presents a qualitative compilation of clinical radiologist opinion, relevant professional recommendations, governmental regulatory positions and prior work on diagnostic error to synthesise recommendations on what clinical information should be included in a referral. Recommended requirements on what clinical information should be included in a referral to a clinical radiologist are as follows: an unambiguous referral; identity of the patient; identity of the referrer; and sufficient clinical detail to justify performance of the diagnostic imaging examination and to confirm appropriate choice of the examination and modality. Recommended guideline on the content of clinical detail clarifies when the information provided in a referral meets these requirements. High-quality information provided in a referral allows the clinical radiologist to ensure that exposure of patients to medical radiation is justified. It also minimises the incidence of perceptual and interpretational diagnostic error. Recommended requirements and guideline on the clinical detail to be provided in a referral to a clinical radiologist have been formulated for professional debate and adoption.

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AIM: Knowledge of the normal range of periprosthetic osteoblastic activity around total hip arthroplasties is required for rational diagnosis of complications. The aim of this study was to establish such a normal range for single-photon emission computed tomography (SPECT). Clinical utility of such a range is confident differentiation of normal from abnormal arthroplasties. METHODS: A total of 122 asymptomatic acetabular cups (age: 0-22 years) and 71 femoral stems (age: 0-20 years) were scanned with SPECT/CT. Two acetabular and three femoral activity ratios to normal reference bone were defined [acetabular axial (AA/RA), acetabular coronal (AC/RA), RA=reference acetabulum; femoral calcar (FC/RF), femoral mid-stem (FM/RF), femoral stem tip (FS/RF), RF=reference femur]. Upper cut-off of normal was defined as mean +3 SD (rounded). Two time breakpoints were analysed (12 and 24 months). RESULTS: The upper cut-off for the normal range was 1.0 for AA/RA, 1.5 for AC/RA and 2.2 for all thee of FC/RF, FM/RF and FS/RF. AA/RA, FM/RF and FS/RF showed no statistically significant temporal trends. AC/RA showed stabilization of activity after 12 months and FC/RF after 24 months. CONCLUSION: Measured activity ratios that fall within our normal range are likely to represent normal periprosthetic osteoblastic activity. Measured activity ratios that fall above the upper cut-offs of our normal range are likely to be abnormal. The cut-offs are robust in clinical practice and have utility in discriminating normal from abnormal stabilized arthroplasties where visual interpretation is ambiguous. Elevated AC/RA under 12 months and FC/RF under 24 months may represent normal periprosthetic activity and should be interpreted with caution.

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INTRODUCTION: A unified and logical system of descriptors for diagnostic imaging examinations and procedures is a desirable resource for radiology in Australia and New Zealand and is needed to support core activities of RANZCR. Existing descriptor systems available in Australia and New Zealand (including the Medicare DIST and the ACC Schedule) have significant limitations and are inappropriate for broader clinical application. METHODS: An anatomically based grid was constructed, with anatomical structures arranged in rows and diagnostic imaging modalities arranged in columns (including nuclear medicine and positron emission tomography). The grid was segregated into five body systems. The cells at the intersection of an anatomical structure row and an imaging modality column were populated with short, formulaic descriptors of the applicable diagnostic imaging examinations. Clinically illogical or physically impossible combinations were 'greyed out'. Where the same examination applied to different anatomical structures, the descriptor was kept identical for the purposes of streamlining. RESULTS: The resulting Body Systems Framework of diagnostic imaging examination descriptors lists all the reasonably common diagnostic imaging examinations currently performed in Australia and New Zealand using a unified grid structure allowing navigation by both referrers and radiologists. The Framework has been placed on the RANZCR website and is available for access free of charge by registered users. CONCLUSION: The Body Systems Framework of diagnostic imaging examination descriptors is a system of descriptors based on relationships between anatomical structures and imaging modalities. The Framework is now available as a resource and reference point for the radiology profession and to support core College activities.

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UNLABELLED: (18)F-FDG PET qualitative tumor response assessment or tumor-to-background ratios compare targets against blood-pool or liver activity; standardized uptake value (SUV) semiquantitation has artifacts and is validated by a stable normal-tissue baseline. The aim of this study was to document the normal intrapatient range of scan-to-scan variation in blood-pool SUV and liver SUV and to identify factors that may adversely affect it (increase its spread). METHODS: Between July 2009 and June 2010, 132 oncology patients had 2 PET/CT scans. Patient preparation, acquisition, and reconstruction protocols were held stable, uniform, and reproducible. Mean SUV (body weight) values were obtained from 2-dimensional regions of interest in the aortic arch blood pool and in the right lobe of the liver. RESULTS: Of the 132 patients, 65 had lymphoma. Their mean age was 62.5 y. The group's mean serum glucose level was 6.0 mmol/L at the first visit and 5.9 mmol/L at the second visit. The mean (18)F-FDG dose was 4.1 MBq/kg at the first visit and 4.0 at the second. At the first visit, the group's mean blood-pool SUV was 1.55 (SD, 0.38); at the second, 1.58 (SD, 0.37)-not statistically different. The group's mean liver SUV was 2.17 (SD, 0.44) at the first visit and 2.29 (SD, 0.44) at the second (P = 0.005). Visit-to-visit intrapatient variation in blood-pool and liver SUVs had gaussian distributions. The variation in blood-pool SUV had a mean of 0.03 and SD of 0.42. The variation in liver SUV had a mean of 0.12 and SD of 0.50. Using 95th percentiles, the reference range in our patient population for intrapatient variation was -0.8 to 0.9 for blood pool SUV and -0.9 to 1.1 for liver SUV. Subanalysis by cancer type and chemotherapy suggested that the rise in liver SUV between the 2 visits was largely due to the commencement of chemotherapy, but no factors were identified as systematically affecting intrapatient variation, and no factors were identified as increasing its spread. CONCLUSION: In our patient cohort, the reference range for intrapatient variation in blood-pool and liver SUVs is -0.8 to 0.9 and -0.9 to 1.1, respectively.

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AIM: To determine if presence of cancer on a mammogram makes that mammogram more memorable. MATERIALS AND METHODS: A total of 100 mammograms (25 cancers) were grouped into 5 sets of 20 cases. Set pairs were presented in five reads to eight radiologist readers. Readers were asked to 'clear' or 'call back' cases, and at post-baseline reads to indicate whether each case was 'new' or 'old' (remembered from prior read). Two sets were presented only at baseline, to calculate each reader's false recollection rate. For cases presented more than once ('old' cases, 100 presentations) readers could have 'correct memory' or 'memory loss'. Memory performance was defined as odds ratio of correct memory to memory loss. Multivariate logistic data regression analysis identified predictors of memory performance from: reader, set, time since last read, presence of cancer, and whether the case was called back at the last read. RESULTS: Memory performance differed markedly between readers and reader identity was a highly significant predictor of memory performance. Presence of cancer was not a significant predictor of memory performance (odds ratio 0.77, 95% CI: 0.49-1.21). Whether the case was called back at the last read was a highly significant predictor (odds ratio 4.22, 95% CI: 2.70-6.61) for the model incorporating reader variability, and also the model without reader variability (odds ratio 2.67, 95% CI: 1.74-4.08). CONCLUSION: The only statistically significant predictor of radiologist memory for a mammogram was whether the radiologist 'called it back' at a prior reading round. Presence of cancer on a mammogram did not make it memorable.

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INTRODUCTION: Paediatric head and neck malignancy accounts for 5% of all paediatric cancers. The choice of treatment and prediction of prognosis depend on the histological type of tumour, initial staging, evaluating treatment response and detection of early recurrence. Conventional imaging modalities have many limitations. Positron emission tomography/computed tomography (PET/CT) is more accurate; however, so far, the literature lacks reports of large groups of paediatric patients. AIM: To report the role of PET/CT in factors affecting the choice of treatment at the newly established Children Cancer Hospital in Cairo, Egypt, which is one of the busiest dedicated paediatric oncology centres in the world. All findings were proven by histopathology, radiology and by clinical follow-up. PATIENT POPULATION: Thirty-six paediatric patients (30 boys and six girls) with various histologically proven head and neck cancers were included in this study. Their age ranged from 2 to 17 years. High-resolution diagnostic CT and/or MRI of the head and neck, and in relevant cases also of the chest and the abdomen, were performed in all patients at a mean interval of 1.6 weeks (range, 1-3 months) before the PET/CT study. Results of PET/CT were compared with the findings of these conventional imaging modalities. RESULTS: The sensitivity, specificity, accuracy, positive and negative predictive values of PET/CT against the conventional imaging were as follows: sensitivity 100 and, 53%, specificity 89.5 and 47%, accuracy 94.5 and 50%, positive predictive value 89.5 and 47% and negative predictive value 100 and 53% respectively. PET/CT changed patient management in 50% of the cases. CONCLUSION: PET/CT in paediatric head and neck carcinoma is more accurate than conventional imaging. Therefore, it also has a significant impact on further patient management. We recommend that it should be the first imaging modality for all purposes in initial staging, evaluating treatment response and follow-up in paediatric head and neck carcinoma.

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AIM: The aim of this study was to evaluate the accuracy and clinical impact of single-reader breast MR (BMR) used as a clinical 'problem solving' tool. METHODS: Observational, retrospective, ethics approved data collection for all BMR were from May 2006 to February 2009 (n=143). Cases were stratified into groups according to indication for referral. MR data included single-reader MR diagnosis and breast imaging reporting and data system category (per-patient basis), MR descriptors of lesions (breast imaging reporting and data system lexicon), lesion number and location. Composite reference standard was established from surgical histology, core histology, cytology, MR imaging follow-up, conventional imaging follow-up and clinical follow-up in that order of priority. Impact was qualitatively captured by estimating change in management as the result of BMR. RESULTS: Eighty-two cases were included and 61 were excluded (41 insufficient follow-up times, three known benign mass for clarification, two worried well screening and 15 other reasons). There was no statistically significant difference in included and excluded patient profiles. Our largest group of referrals was of patients with suspicious or unhelpful conventional imaging. BMR identified five malignancies in that group but missed four. In our smaller group of patients with metastatic axillary lymph nodes, BMR identified the occult primary cancer in all five cases. CONCLUSION: In this 'problem solving' patient population, breast MR shows greatest impact in patients with carcinoma metastases to axillary nodes, but primary not visible. In symptomatic women with unhelpful imaging or with suspicious imaging but no pre-MR diagnosis, MR identified 5/41 carcinomas, but missed 4/41.

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INTRODUCTION: The purpose of this study was, for a group of experienced radiologists, to identify the magnitude of and statistical significance of intrareader variability in mammographic diagnostic performance or cancer diagnosis and mammographic perceptual performance or microcalcification detection. METHODS: Eight radiologist readers (8-30 years experience in radiology, five current BreastScreen readers) read a set of 100 digital mammograms on two separate reads with random case orders. Twenty-three of the 100 had proven malignancies, and 52 of the 100 had confirmed microcalcifications. The same mammograms were presented for both reads. The radiologists were requested to clear or call back cases and to indicate if any benign and malignant microcalcifications were present on the mammograms. Reading conditions were standardised. RESULTS: Intrareader variability in accuracy was demonstrated to be between 0% and 6% for the diagnostic task of breast cancer diagnosis and between 0% and 16% for the perceptual task of microcalcification detection. Intrareader agreement in the group of readers was high; between 75% and 93% (κ=0.36-0.72) for cancer diagnosis and between 77.5% and 93% (κ=0.17-0.77) for microcalcification detection. There was no correlation between reader's experience in radiology or being a BreastScreen reader and level of intrareader variability in cancer diagnosis and microcalcification detection. CONCLUSION: There exists intrareader variability in diagnostic and perceptual performance. Despite this variability, intrareader agreement remains high.

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To bring to the attention of Australian radiologists in training, directors of training and radiologists in general, a commonly held erroneous misconception, specifically that of the plain radiographic appearance of the cervical spine pedicle and the transverse process in oblique projections. A human C5 vertebra was appropriately marked and radiographed in the oblique projection to demonstrate key anatomical structures and their relations. The rounded cortical contour overlying the vertebral body is commonly misinterpreted as a cervical transverse process but is the plain radiographic outline of the end-on ipsilateral pedicle. Because of the right-angle relationship of the transverse process long axis and the end-on pedicle long axis, the ipsilateral transverse process appears as a faint elongated corticated structure projecting beyond the vertebral body contour. It may also be obscured because of small size, relative osteopaenia and overlying soft tissue bulk. The end-on pedicle has been unequivocally demonstrated, as has the ipsilateral transverse process. The two lie at right angles to each other. The common misconception (amplified by an error in an earlier edition of a popular atlas) should be debunked by radiologists and should not be promulgated to Australian radiology trainees.

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INTRODUCTION: Picture archiving and communication systems images designed to be viewed on high-resolution medical-grade monitors are routinely viewed on office-grade monitors on the wards or at home. This study aimed to determine whether a statistically significant difference in diagnostic (cancer detection) and perceptual (microcalcification detection) performance exists between 3MP grade and 1MP office-grade monitors. METHODS: 3MP Dome medical-grade liquid crystal display (LCD) monitors (Planar, Beaverton, OR, USA) were compared to 1MP Dell office-grade LCD monitors (Dell Inc, Round Rock, TX, USA). Eight radiologists (reader experience 8-30 years) read the same set of 100 mammograms (23/100 with proven cancers and 52/100 with microcalcifications) presented in random order on three occasions separated by two time intervals of 12 weeks. Reads 1 and 3 utilised 3MP monitors and formed the baseline read. Read 2 utilised 1MP monitors and constituted the experimental read. Reading conditions were standardised. Readers were aware of which monitors they were using. Multivariate logistic regression analysis (to account for reader variability and monitor impact) was performed to assess for statistical significance. RESULTS: At α = 5%, confidence intervals analysis comparing the measured parameters between 1MP to 3MP monitors demonstrated no statistically significant difference in diagnostic and perceptual performance for the reader group. In cancer detection (the diagnostic task), reader accuracy remained high irrespective of monitor type. Regression analysis comparing performance with 1MP against 3MP monitors found P values of 0.693 and 0.324 for diagnostic and perceptual performance, respectively. CONCLUSION: There were no statistically and clinically significant differences between 3MP and 1MP monitors in mammographic diagnostic and perceptual performance. Comparable performance may be due to compensatory behaviour by readers.

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INTRODUCTION: There has been growing interest in the use of MRI in assessing Crohn's disease because of its lack of ionising radiation. Many MRI signs have been described in the literature, but their relative utility is unknown. METHODS: The MRIs of the bowel performed at 1.5 Tesla were blindly reviewed on 26 patients with recent histology (surgery and/or colonoscopy and their associated reports) according to a dedicated pro forma. Each patient's bowel was divided into nine segments. Each segment was assessed as to the presence or absence of 15 MRI signs described in the literature: abnormal gadolinium enhancement (both subjective and objective), wall oedema, fat oedema, fat proliferation, nodal enlargement, free fluid, wall nodularity, serosal blurring, mural thickening >4 mm, stricture, multi-segmental disease, fistula, abscess and layered contrast enhancement. The results were compared against a histological gold standard with a six-point scale of disease severity. RESULTS AND CONCLUSIONS: MRI correctly identified all 15 patients with at least established mucosal disease, and three of eight with only mild mucosal disease. Combining these results, a positive MRI correlated highly with at least early mucosal disease (positive predictive value 95%), while the presence of established mucosal disease was unlikely if MRI was negative (negative predictive value 100%). The MRI signs found to be the most sensitive for detecting active Crohn's disease were those related to the bowel wall, namely, wall thickening, nodularity, contrast enhancement and oedema. The most specific signs were the presence of multi-segmental disease, layered contrast enhancement and complications (fistula and abscess).

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In April 2004, Melbourne's Peter MacCallum Cancer Centre, Australia's only stand-alone dedicated cancer hospital, became the first Australian site to offer digital mammography (DM). In the first year of DM operation, 1208 mammograms were performed on 1157 women; 17 new cases of invasive carcinoma and six new cases of ductal carcinoma-in-situ (DCIS) were detected; and 30 hook-wire needle localisations were conducted in 29 patients. We developed a unit policy to manage indeterminate microcalcifications newly demonstrated on DM that were not previously detected by conventional screen-film mammography (CM): those believed to have malignant morphology were recommended for biopsy, and those without were recommended for 6-month DM follow-up to confirm microcalcification stability. DM detected 56 new stand-alone microcalcifications (18 suspicious and 38 indeterminate). Tissue diagnosis of 12 suspicious microcalcifications yielded four cases of DCIS and one of atypical ductal hyperplasia. Of the indeterminate microcalcifications, 35 have demonstrated stability at DM follow-up to date, over a mean period of 23.6 months. From our experience, we believe DM's superior demonstration ability uncovered microcalcifications previously undetected by CM, rather than microcalcification progression. We suggest that routine review with DM, rather than biopsy, is appropriate management when new indeterminate microcalcifications without malignant characteristics are identified by DM.

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PURPOSE: We reviewed the clinical outcome for patients who underwent decompression of malignant ureteral obstruction by analyzing potential prognostic factors, technical success, complication rates and days spent in hospital. MATERIALS AND METHODS: Retrospective analysis of 102 patients who underwent decompression for malignant ureteral obstruction from 1991 to 2003 was performed. Data on overall survival, prognostic factors, technical failure, complications and days of hospitalization after decompression were examined. RESULTS: Median overall survival was 6.8 months (95% CI 4.8-9.3) and the overall survival rate at 12 months was 29% (95% CI 21%-39%). Univariate analyses found inferior overall survival associated with patients having metastases (p=0.041), undergoing nephrostomy (p=0.046), prior treatment for cancer (p=0.024) and diagnosis of malignant ureteral obstruction in previously established malignancy (p=0.043). After multivariate analysis poor prognostic factors were presence of metastases (p=0.020) and diagnosis of malignant ureteral obstruction in previously established malignancy (p=0.039). Unfavorable cohorts with 3 or 4 unfavorable baseline risk factors had an inferior overall survival (p=0.008) with 12-month overall survival rates of 12% to 19%. Initial decompression of malignant ureteral obstruction failed in 6% of patients (95% CI 2%-12%) and complications were experienced by 53% (95% CI 43%-63%). Patients were more likely to experience a complication if they had therapy after decompression (p=0.03). The median percentage of their remaining lifetime spent in hospital was 17.4% (range 0.21% to 100%). CONCLUSIONS: The overall survival of patients with malignant ureteral obstruction remains poor. Prognostic factors for decreased overall survival and prolonged hospital stay have been identified. Although the technical success of decompression has improved the subsequent complication rate is still high.

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BACKGROUND AND PURPOSE: This prospective study sought to determine how the use of combined PET/CT for radiotherapy treatment planning of oesophageal cancer would alter the delineation of tumour volumes compared to CT alone if PET/CT is assumed to more accurately represent true disease extent. PATIENTS AND METHODS: All patients underwent FDG-PET/CT scanning in the radiotherapy treatment position. For each patient, two separate gross tumour volumes (GTV) were defined, one based on CT images alone (GTV-CT) and another based on combined PET/CT data (GTV-PET). Corresponding planning target volumes (PTV) were generated, and separate treatment plans were then produced. For each patient, volumetric analysis of GTV-CT, PTV-CT and GTV-PET was performed to quantify the proportion of PET-avid disease that was not included in the GTV and PTV (geographic miss) if CT data alone were used for radiotherapy planning. Assessment of the cranial and caudal extent of the primary oesophageal tumour as defined by CT alone vs PET/CT was also compared. RESULTS: The addition of PET information altered the clinical stage in 8 of 21 eligible patients enrolled on the study (38%); 4 patients had distant metastatic disease and 4 had unsuspected regional nodal disease. Sixteen patients proceeded to the radiotherapy planning phase of the study and received definitive chemoradiation planned with the PET/CT data set. The GTV based on CT information alone excluded PET-avid disease in 11 patients (69%), and in five patients (31%) this would have resulted in a geographic miss of gross tumour. The discordance between CT and PET/CT was due mainly to differences in defining the longitudinal extent of disease in the oesophagus. The cranial extent of the primary tumour as defined by CT vs PET/CT differed in 75% of cases, while the caudal extent differed in 81%. CONCLUSIONS: This study demonstrates that if combined PET/CT is used for radiotherapy treatment planning, there may be alterations to the delineation of tumour volumes when compared to CT alone, with the potential to avoid a geographic miss of tumour.

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BACKGROUND: Subdiaphragmatic activity and diaphragmatic motion both contribute to inferior wall artifacts in technetium 99m myocardial perfusion single photon emission computed tomography (SPECT). METHODS AND RESULTS: We used an anthropomorphic phantom with ventricular wall activity, liver/spleen inserts containing variable Tc-99m activity, and variable vertical (diaphragmatic) motion amplitude. SPECT and transmission scans were obtained on a GE Optima NX camera. Data were processed by use of filtered backprojection or attenuation correction (AC). Resulting myocardial activity maps were analyzed with standardized inferior-anterior and anterior-lateral wall ratios. At a subdiaphragmatic-myocardial activity ratio of 0.5:1, inferior wall attenuation predominates, producing a cold artifact. AC corrects inferior wall activity to the level of the anterior wall irrespective of diaphragmatic motion. At a subdiaphragmatic-myocardial activity ratio of 1:1, inferior wall counts vary widely depending on the proximity of subdiaphragmatic activity to the ventricle. With increasing diaphragmatic amplitude, the overlap of subdiaphragmatic activity and inferior wall worsens, leading to a complex mixture of cold and hot artifacts, not corrected by AC. CONCLUSIONS: Concentration and proximity of subdiaphragmatic Tc-99m activity relative to myocardium comprise a major factor in the nature and severity of inferior wall artifacts. If the subdiaphragmatic Tc-99m concentration is equivalent to that in the myocardium, complex, potentially uninterpretable hot and cold inferior wall artifacts are produced.

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