The where, who and how of adrenal vein sampling in Australia and New Zealand.

INTRODUCTION: Primary aldosteronism (PA) causes 10-15% of cases of hypertension, and it is increasingly recognised as being under-diagnosed. An interventional radiology procedure, adrenal vein sampling (AVS), is a necessary and important diagnostic procedure for complete workup of PA. There is an anticipated increase in demand for AVS as detection of PA improves. This study aims to describe the current landscape of AVS in Australia and New Zealand (NZ). METHODS: Two surveys exploring AVS methodology and performance were conducted of (i) Endocrinology Unit Heads and (ii) interventional radiologists who perform AVS, at public hospitals with Endocrinology Units across Australia and NZ. RESULTS: Responses were received from 48/53 Endocrinology Unit Heads (91%) and 35 radiologists from 26 sites (87% of AVS sites). AVS was provided at 28/48 Endocrinology sites (58%) across Australia and NZ. In Australia, sites were concentrated in Victoria, New South Wales and Queensland with none in the Northern Territory; in NZ, sites were more evenly distributed across the North and South Islands. AVS was performed by 1-2 dedicated radiologists at 24 sites, 2-3 radiologists at two sites and a rotating roster of radiologists at two sites. Responses to both surveys revealed significant variation in AVS methodology and interpretation of AVS results. CONCLUSION: There is significant heterogeneity in the availability of AVS, the procedural details and the interpretation of results across Australia and NZ, which potentially impacts the quality of patient care and ability to scale up AVS capacity to meet increasing demand.

High-pitched tin-filtered CT pulmonary angiography in radiation dose reduction for pulmonary embolism investigations in young females.

INTRODUCTION: Computed tomography pulmonary angiography (CTPA) is the gold standard test to investigate pulmonary embolism (PE). This technique carries significant radiation risk in young females because of radiosensitive breast and thyroid tissues. A high-pitched CT technique offers significant radiation dose reduction (RDR) and minimises breathing artefact. The addition of CT tube tin-filtration may offer further RDR. The aim of this retrospective study was to assess RDR and image quality (IQ) of high-pitch tin-filtered (HPTF)-CTPA against conventional-CTPA. METHODS: Retrospective review of consecutive adult females age < 50 years undergoing high pitch tin filtration (HPTF) and standard pitch no tin filtration (SPNF) during a 3-year period beginning in November 2017. CTs in both groups were compared for radiation dose, pulmonary arteries contrast density (Hounsfield units (HU)) and movement artefact. Findings of both groups were compared with the Student's T-test and Mann-Whitney U test, where p < 0.05 being considered significant. Diagnostic quality was also recorded. RESULTS: Ten female patients (mean age 33, 6/10 pregnant) in HPTF group and 10 female patients (mean age 36, 1/10 pregnant) in SPNF group were included. The HPTF group achieved 93% RDR (dose length product: 25.15 mGy.cm vs 337.10 mGy.cm, p < 0.01). There was significant contrast density difference between the two groups in the main, left or right pulmonary arteries (322.72 HU, 311.85 HU and 319.41 HU in HPTF group vs 418.60 HU, 405.10 HU and 415.96 HU in SPNF group respectively, p = 0.03, p = 0.03 and p = 0.04). 8/10 HPTF group and 10/10 in the control group were > 250 HU in all three vessels; the remaining 2 HPTF CTPA were > 210HU. All CT scans in both groups were of diagnostic quality and none exhibited movement artefact. CONCLUSION: This study was the first to demonstrate significant RDR with the HPTF technique whilst maintaining IQ in patients undergoing chest CTPA. This technique is particularly beneficial in young females and pregnant females with suspected PE.

Persistent median artery on computed tomographic arteriovenous fistulograms in patients on haemodialysis.

INTRODUCTION: Cadaveric studies suggest an increasing prevalence of the persistent median artery (PMA) over a prolonged timeframe. The aim of this retrospective cross-sectional study was to evaluate the PMA prevalence in haemodialysis patients who had computed tomographic fistulograms (CTFs), and if present, their calibres and origins. METHODS: All consecutive adult patients referred for an upper limb CTFs for assessment of arteriovenous fistula (AVF) dysfunction from 2006 to 2021 were included. Patients whose CTF did not include the forearm were excluded. PMA was identified as an artery running alongside the median nerve between flexor digitorum superficialis and flexor digitorum profundus. Patient demographics, presence of PMA including size and origin were recorded. RESULTS: A PMA was found in 91/170 (53.5%) CTFs (7:3 male-to-female ratio, mean age 71-years). When stratified by age, prevalence increased with decreasing age; 51% in >70-year-olds, 54% in 50-70-year-olds and 67% in <50-year-olds. The average PMA diameter was 2.2 mm proximally and 1.8 mm distally. No stenosis was observed in the PMAs. CONCLUSION: The PMA prevalence appears to increase with decreasing age and is a frequently encountered anatomical variant. Radiologists assessing forearm vasculature need to be aware of this anatomical variant and potentially include it in their future reports. Further research into the PMA may make its potential use as arterial conduits for AVF, potential donor grafts for coronary artery bypass surgery or additional vascular access options possible. Whether the reducing prevalence with age reflects an overall increasing prevalence is yet to be determined.

Computed Tomography Imaging of the Larynx for Diagnosis of Vocal Cord Dysfunction.

BACKGROUND: Vocal cord dysfunction/inducible laryngeal obstruction (VCD/ILO) is characterized by breathlessness and often mimics or accompanies severe asthma. The disorder occurs intermittently, and the diagnosis is established by using laryngoscopy. Dynamic computed tomography (CT) imaging of the larynx at low-radiation doses has the potential to provide an alternative method to make the diagnosis of VCD/ILO. METHODS: We report two case series: in series A, laryngoscopy (diagnostic standard) and CT imaging of the larynx were each performed within 1 hour of each other (n=31), and in series B, the procedures were performed on separate days 4 to 6 weeks apart (n=72). Diagnosis of VCD/ILO by laryngoscopy used conventional criteria, and diagnosis by CT imaging was based on vocal cord narrowing in excess of a validated normal threshold. In each series, we evaluated the accuracy of CT imaging of the larynx to establish a diagnosis of VCD/ILO compared with laryngoscopy. RESULTS: In series A, the sensitivity of CT imaging of the larynx was 53.8%, and specificity was 88.9%; in series B, the sensitivity of CT imaging of the larynx was 76.2%, and specificity was 93.3%. At a disease prevalence of 30% (which was known to be the case in our clinic), the positive predictive value was 67.5% in series A and 83% in series B. Negative predictive values were 81.8% and 90.1% in series A and B, respectively, and false-positive rates were 11.1% and 6.7%. CONCLUSIONS: When the population prevalence was assumed to be 30%, low-dose CT imaging of the larynx detected VCD/ILO with negative predictive values greater than 80% in both series settings and agreed with each other within 9 percentage points. Positive predictive values for laryngeal CT imaging varied substantially between the settings of the two case series. (Supported by Monash Lung and Sleep Institute and Grant APP ID 1198362 and others.)

Granulomatosis with polyangiitis: Common and uncommon presentations.

Granulomatosis with polyangiitis (GPA) is a multisystemic autoimmune small vessel vasculitis predominantly affecting the respiratory and renal systems. Other systems such as the central nervous system, orbital, cardiac and gastrointestinal systems may also be involved to a lesser degree. Although there are no imaging features that are pathognomonic for GPA, there are known radiological patterns suggestive of the disease and imaging plays an important role in diagnosis, assessment and monitoring of disease activity. This is more evident when combined with clinical features, biochemical values and histopathology results. This pictorial review aims to present both common and uncommon radiological features of GPA.

Current trends in image-guided chest interventions.

Interventional radiology (IR) is a rapidly expanding medical subspecialty and refers to a range of image-guided procedural techniques. The image guidance allows real-time visualization and precision placement of a needle, catheter, wire and device to deep body structures through small incisions. Advantages include reduced risks, faster recovery and shorter hospital stays, lower costs and less patient discomfort. The range of chest interventional procedures keeps on expanding due to improved imaging facilities, better percutaneous assess devices and advancing ablation and embolization techniques. These advances permit procedures to be undertaken safely, simultaneously and effectively, hence escalating the role of IR in the treatment of chest disorders. This review article aims to cover the latest developments in some image-guided techniques of the chest, including thermal ablation therapy of lung malignancy, targeted therapy of pulmonary embolism, angioplasty and stenting of mediastinal venous/superior vena cava occlusion, pulmonary arteriovenous malformation treatment and bronchial artery embolization for haemoptysis.

Venous air embolism in CT coronary angiography.

INTRODUCTION: Venous air embolization (VAE) from IV lines is a risk with IV contrast administration. The incidence of VAE ranges from 7% to 23%. While life-threatening VAE is rare, there is the potential risk of serious cerebrovascular events from paradoxical systemic air embolization (SAE) in patients with congenital intracardiac shunts. CT coronary angiogram (CTCA) hypothetically carries a higher risk of VAE as it requires dual injections as compared to single bolus dose contrast used in CT chest (CTC). The aim of this study was to assess the risk of VAE using CTCA as compared to conventional CTC. The incidence of cardiac shunts and their association with paradoxical SAE were also investigated. METHODS: A retrospective study was conducted at a tertiary hospital. Adult patients undergoing CTCA and CTC over a 6-month period in 2017 were included. Images were reviewed on PACS for the presence of VAE. Electronic medical records were interrogated for evidence of neurological sequelae or requiring neurological imaging (CTB/MRIB) within 1 month of the initial imaging. RESULTS: 508 patients were included, 408 underwent CTCA and 100 underwent CTC. The VAE incidence in CTCA was 24% (94 patients) and 10% in the CTC (10 patients). This was statistically significant. Among the CTCA group, 36% (108 patients) had an intracardiac shunt. No statistically significant difference in VAE incidence was identified in CTCA patients with shunts vs without shunts. There was no incidence of SAE in both groups. CONCLUSION: VAE is more common with CTCA than conventional CTC. There were no cases of paradoxical SAE found.

An up-to-date review of cardiac pacemakers and implantable cardioverter defibrillators.

Cardiac pacemakers are one of the most frequently encountered cardiac devices seen on chest imaging. They may include single or dual chamber pacemakers, automated implantable cardioverter defibrillators (AICD), biventricular pacemakers used for cardiac resynchronisation therapy (CRT), wireless CRT, leadless pacemakers, and subcutaneous implantable cardioverter defibrillators (SICD). This review aims to provide an up-to-date review on current implantable pacemaker and defibrillator devices.

The other side tells the story.

We present a patient who presented to the emergency department with a bisphosphonate-induced femoral fracture (BIFF). Clinical presentation, pathogenesis and management of BIFF are discussed. We also highlight the importance of imaging the contralateral femur, as these patients may need prophylactic surgical fixation of the contralateral femur.

Image quality comparison between model-based iterative reconstruction and adaptive statistical iterative reconstruction chest computed tomography in cystic fibrosis patients.

INTRODUCTION: Cystic fibrosis (CF) predominantly affects young adults. Accurate radiological assessment of pulmonary disease is vital for predicting exacerbations, one of the leading causes of morbidity and mortality. We evaluated the image quality of model-based iterative reconstruction (MBIR) ultra-low-dose CT chest (ULD-CT) in CF evaluation. METHODS: We compared ULD-CT with standard adaptive statistical iterative reconstruction (ASIR) low-dose CT (LD-CT). Subjective assessment of contrast and noise were performed for each study. Background noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated and compared between the CT studies. Conspicuity of major structures was assessed. These aspects of image quality were compared to determine whether ULD-CT was superior to LD-CT in assessment of CF. RESULTS: The ULD-CT achieved median effective dose of 0.073 mSv, comparable to one standard chest radiograph and significantly lower than the median LD-CT dose of 1.22 mSv. ULD-CT had lower subjective contrast and higher subjective noise when compared to LD-CT. Objectively measured background noise was lower in ULD-CT (16.33 HU vs 38.53 HU, P < 0.0001) compared to LD-CT. ULD-CT had higher median CNR (52.65 vs 22.09, P < 0.0001) and SNR in lung (9.08 vs 7.29, P = 0.002) compared to LD-CT. ULD-CT was equal to LD-CT in identification of trachea, bronchi, pleural and pericardium. Interobserver reliability showed agreement of 80-92%. CONCLUSIONS: The image quality of ULD-CT is similar to LD-CT, at 1/16th the dose. MBIR constructed ULD-CT is an effective imaging modality for CF surveillance, with potential applications in other disease settings.

An Uncommon Presentation of a Primary Bone Tumor: Anti-AMPA (Anti-α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic acid) Receptor Limbic/Paraneoplastic Encephalitis as a Presenting Feature of Ewing Sarcoma.

Anti-AMPA (anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor limbic encephalitis is a rare autoimmune syndrome. It can be associated with an underlying malignancy, such as lung, breast, or thymus. We are reporting a case of a 19-year-old patient who presented with a 2-week history of confusion and short-term memory loss. A magnetic resonance imaging of brain showed increased T2 hyperintensity within the hippocampi bilaterally. Cerebrospinal fluid analysis was positive for anti-AMPA receptor antibodies. A computed tomography revealed multiple pulmonary metastases as well as an expansile lucent and sclerotic lesion in the ilium, which was subsequently biopsied. Histopathology confirmed a diagnosis of Ewing sarcoma (ES). Fluorescence in situ hybridization testing of the specimen identified EWSR1 (22q12.2) signal rearrangements in 80% of cells scored. To date, this is the first case report describing anti-AMPA receptor limbic/paraneoplastic encephalitis as a presenting feature of ES. Although it is rare, the possibility of ES may be considered in young patients presenting with anti-AMPA receptor limbic encephalitis.

Are all urgent nephrostomies that urgent?

PURPOSE: To investigate if the presence of systemic inflammatory response syndrome (SIRS) in patients with urinary tract obstruction at time of presentation to the emergency department correlates with a subsequent positive urine culture and to determine if it could be used as a tool to predict the urgency of a percutaneous nephrostomy (PCN). The secondary aim of the study was to assess the incidence of in-hour and after-hour emergent PCNs performed in a tertiary center which has both interventional radiological and urological expertise. METHODS AND MATERIALS: Emergent adult PCN cases referred from the emergency department between 2011 and 2016 were identified retrospectively. Urine culture results, clinical features of SIRS, timing of procedure, and radiological findings were analyzed. RESULTS: A total of 110 patients met the inclusion criteria. There were a total of 60 male and 50 female patients with a mean age of 62 (age range 18-99 years). Ninety-two (83%) PCN patients were referred and performed on after-hours with the remaining 18 patients performed in-hours. There were 53 (48%) patients that met the criteria for obstruction with SIRS and 57 (52%) patients with obstruction without SIRS. The number of after-hours PCN performed in both groups was equal at 46 patients each. The most common cause of obstruction in the SIRS group was stone related in 31 (58%) patients. Whereas, the most common cause of obstruction in the non-SIRS group was due to malignancy in 26 (45%) cases. An elevated temperature and heart rate were the most common features of SIRS at 96 and 83% respectively in the SIRS group. An organism was isolated in 35 (67%) out of the 52 urine culture results obtained for the SIRS group. No organism was isolated in 42 (95%) out of the 44 urine culture results obtained in the non-SIRS group. Statistical analysis using Fisher's test revealed that the association between obstruction without SIRS and a negative urine culture result was statistically significant (p < 0.0001). CONCLUSION: A large percentage (50%) of PCN cases performed after-hours could have been performed during daytime hours instead due to the absence of infection. This would be in line with the practices of some centers that consider an infected obstructed kidney as the only absolute indication for emergent decompression overnight. The study also demonstrates that the absence of a SIRS in a patient with urinary tract obstruction correlates well with a negative urine culture result from the nephrostomy specimen which has a high negative predictive value for excluding pyonephrosis.

Novel application of four-dimensional wide-area detector computed tomographic angiography for investigation of median arcuate ligament syndrome.

The median arcuate ligament syndrome is a rare disorder characterised by postprandial intestinal angina caused by compression of the coeliac artery by the median arcuate ligament. To date, the diagnosis and treatment of median arcuate ligament syndrome has remained controversial. To our knowledge, this is the first reported case of coeliac artery compression demonstrated on the four-dimensional wide-area detector CT angiogram.

Fine focal spot size improves image quality in computed tomography abdomen and pelvis.

OBJECTIVES: To compare the image quality between fine focal spot size (FFSS) and standard focal spot size (SFSS) in computed tomography of the abdomen and pelvis (CTAP) METHODS: This retrospective review included all consecutive adult patients undergoing contrast-enhanced CTAP between June and September 2014. Two blinded radiologists assessed the margin clarity of the abdominal viscera and the detected lesions using a five-point grading scale. Cohen's kappa test was used to examine the inter-observer reliability between the two reviewers for organ margin clarity. Mann-Whitney U testing was utilised to assess the statistical difference of the organ and lesion margin clarity. RESULTS: 100 consecutive CTAPs were recruited. 52 CTAPs were examined with SFSS of 1.1 × 1.2 mm and 48 CTAPs were examined with FFSS of 0.6 × 0.7 mm. Results showed that there was substantial agreement for organ margin clarity (mean κ = 0.759, p < 0.001) among the reviewers. FFSS produces images with clearer organ margins (U = 76194.0, p < 0.001, r = 0.523) and clearer lesion margins (U = 239, p = 0.052, r = 0.269). CONCLUSION: FFSS CTAP improves image quality in terms of better organ and lesion margin clarity. Fine focus CT scanning is a novel technique that may be applied in routine CTAP imaging. KEY POINTS: • Fine focal spot improves organ margin clarity. • Fine focal spot improves lesion margin clarity. • Fine focal spot can be used in routine CT abdominal imaging.