Sonographic risk stratification of FDG-avid thyroid nodules using the Thyroid Imaging Reporting and Data System.

INTRODUCTION: The increasing usage of positron emission tomography/computed tomography (PET/CT) for detection and monitoring of malignancy has led to an increase in incidental detection of thyroid nodules. Nodules that demonstrate increased avidity for 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) have been shown to carry a high incidence of malignancy and warrant further investigation. At present, there has been limited research on the risk stratification of FDG-avid thyroid incidentalomas. Thus, this study aims to evaluate the efficacy of the ACR TIRADS classification in the risk stratification of such nodules. METHODS: Data were collected retrospectively for FDG-avid thyroid incidentalomas over a 10-year period. Nodules were characterised using the TIRADS classification and, subsequently, underwent fine-needle aspirate cytology. Cytological findings were classified using the Bethesda reporting system. Non-diagnostic samples (Bethesda class I) were excluded. The remaining samples were divided into two groups: benign (Bethesda class II) or suspicious for malignancy/malignant (Bethesda class III or above). RESULTS: Thirty-six percent of low-risk nodules and 45% of high-risk nodules were malignant, respectively (P = 0.516). The sensitivity and specificity of TIRADS for detection of malignant nodules were 56% and 54%, respectively. There were no malignant TIRADS 1 or 2 nodules. The absence of any suspicious sonographic features had a 1.0 negative predictive value. CONCLUSIONS: FDG-avid nodules classified as TIRADS 1 or 2 or have no suspicious ultrasound features have a 0% incidence of malignancy and thus may not require further assessment with fine-needle aspirate cytology (FNA) when detected incidentally. FDG-avid nodules that are TIRADS 3 or above should undergo FNA regardless of size due to the high risk of malignancy and poor sensitivity of the TIRADS classification system.

Which test is the best? An updated literature review of imaging modalities for acute ankle diastasis injuries.

Ankle diastasis injuries, or ankle syndesmotic injuries, are common among athletes who usually experience a traumatic injury to the ankle. Long-term complications are avoidable when these injuries are diagnosed promptly and accurately treated. Whilst ankle arthroscopy remains the gold standard diagnostic modality for ankle diastasis injuries, imaging modalities are still widely utilised due to the treatment having greater accessibility, being less invasive and the most cost effective. There are various imaging modalities used to diagnose diastasis injuries, varying in levels of specificity and sensitivity. These observation methods include; X-ray, computed tomography (CT), magnetic resonance imaging (MRI) and ankle arthroscopy. This article uncovers common criteria and parameters to diagnose diastasis injuries through the implementation of different imaging modalities. The conclusions addressed within this article are deduced from a total of 338 articles being screened with only 43 articles being selected for the purposes of this examination. Across most articles, it was concluded that that plain X-ray should be used in the first instance due to its wide availability, quick processing time, and low cost. CT is the next recommended investigation due to its increased sensitivity and specificity, ability to show the positional relationship of the distal tibiofibular syndesmosis, and reliability in detecting minor diastasis injuries. MRI is recommended when ankle diastasis injuries are suspected, but not diagnosed on previous imaging modalities. It has the highest sensitivity and specificity compared to X-ray and CT.

Incidence of residual perfusion defects by lung scintigraphy in patients treated with rivaroxaban compared with warfarin for acute pulmonary embolism.

Residual perfusion defects (RPD) as detected by lung scintigraphy occur in over 50% of patients with acute pulmonary embolism (PE) treated with vitamin K antagonists but there is lack of data in patients treated with direct oral anticoagulants. The aim of this retrospective study was to estimate the incidence of RPD detected by ventilation perfusion (VQ) scan at 3-6 months in patients with first acute symptomatic PE treated with rivaroxaban compared to warfarin. Consecutive eligible patients treated with rivaroxaban as part of a previous study were identified. The Monash Health Radiology database was used to identify a historical cohort of age matched (± 5 years) patients treated with warfarin. Follow-up VQ scans were classified as normal (no perfusion defect) or abnormal (matched or unmatched perfusion defects) by two independent nuclear medicine physicians blinded to treatment. Any disagreement was resolved by consensus. One hundred and ninety patients with PE (95 in each cohort) were included (mean age 56.8 years; 41.1% males; 54.2% unprovoked). In the overall cohort, 31.1% had RPD with a significantly lower incidence of RPD in rivaroxaban treated patients 23.2% (95% CI 15.8-32.6), compared to warfarin 38.9% (95% CI 29.8-49.0). Treatment with rivaroxaban was associated with a significantly lower incidence of RPD detected by VQ scan at 3-6 months compared to warfarin. This supports recent in-vitro data suggesting an indirect enhancement of fibrinolysis by direct oral Xa inhibitors but requires confirmation in larger studies.

The role of scintigraphy and ultrasound in the imaging of neonatal hypothyroidism: 5-year retrospective review of single-centre experience.

INTRODUCTION: Congenital hypothyroidism (CH), as indicated by an elevation of capillary thyroid-stimulating hormone (TSH) at newborn screening, is a preventable cause of mental retardation with varying aetiology; it can be transient or permanent. Radionuclide assessment is currently the gold standard for imaging CH. This study aimed to (i) review the different scintigraphic patterns and correlate them with TSH levels/patient outcomes, (ii) assess the role of sonography in neonates with apparent agenesis as indicated by scintigraphy and (iii) develop a diagnostic investigative algorithm. METHODS: The technetium thyroid scans of 83 consecutive patients (49 females, average age 32 days) with CH scanned between 2005 and 2009 were retrospectively reviewed. Two nuclear medicine physicians blinded to the clinical details interpreted the scans in consensus. Scintigram appearances were categorised into five groups. Patients scintigraphically diagnosed with thyroid agenesis were evaluated with ultrasound. TSH values and scintigraphic and sonographic findings were correlated with patients' final diagnosis. RESULTS: Based on scintigraphy, 14, 13 and 19 patients out of 83 were assessed as having normal thyroid sites with normal, increased and decreased uptake, respectively. Twenty-two of 83 patients had no uptake, and 15 of 83 patients had ectopic uptake. Higher median TSH levels were seen in no-uptake and ectopic uptake subgroups. Eighteen of 22 patients with no uptake were evaluated with ultrasound. Three of the 18 patients had a normal thyroid gland, and three of 18 patients had a hypoplastic thyroid. CONCLUSION: Scintigram findings in patients with congenital hypothyroidism fall into five major categories, which have therapeutic implications (lifelong thyroxine in agenesis versus trial of stopping thyroxine in other subgroups). Sonographic demonstration of thyroid tissue in patients scintigraphically diagnosed with thyroid agenesis has major management implications.

The utility of the Wells clinical prediction model and ventilation-perfusion scanning for pulmonary embolism diagnosis in pregnancy.

Pulmonary embolism is one of the leading causes of mortality in pregnancy in the Western world. No clinical prediction models have been validated in pregnancy. As a result, any pregnant woman presenting with signs possibly consistent with pulmonary embolism is investigated radiologically. This study investigates whether using clinical prediction models for pulmonary embolism in pregnancy should be pursued in future prospective trials. The aim of this study was to retrospectively evaluate the Wells clinical prediction model and ventilation-perfusion scanning for pulmonary embolism in pregnancy. A retrospective study was performed on consecutive pregnant women who presented with suspected pulmonary emboli and underwent ventilation perfusion scanning at two tertiary institutions from 2007 until 2010. The clinical pretest probability was determined as likely or unlikely by two independent clinicians retrospectively using Wells-modified criteria. Scans were determined as normal, nondiagnostic or high probability for pulmonary emboli independently by two experienced radiologists. Disagreements were resolved by a third assessor independently. In 183 pregnant women, the pretest probability was determined as 'pulmonary emboli likely' in 76 (42%) and 'pulmonary emboli unlikely' in 107 (58%) of women. Scans were of high probability in four (2%), nondiagnostic in six (3%) and normal in 173 (95%) of women. This gives the pretest probability using Wells-modified criteria a sensitivity of 100% [95% confidence interval (CI) 0.4-1.0] and a negative predictive value of 100% (95% CI 0.96-1.0). A structured clinical model such as modified Wells criteria may be useful in pregnancy, but further prospective evaluation is required.

Review of cardiomyopathy imaging.

Cardiomyopathies are increasingly being detected on both routine and non-routine imaging. Furthermore, the diagnosis of cardiomyopathy is changing from the traditional method of clinical presentation and cardiac morphology to a quantifiable method based on both cardiac morphology and function. With cardiac magnetic resonance imaging, coronary computed tomography and nuclear medicine increasingly being utilized along with echocardiography in the diagnostic process, it is important for the radiologist to be aware of the relevant criteria in formulating a diagnosis. We aim to provide an overview of the imaging characteristics of the most commonly encountered cardiomyopathies.

Normal paediatric bone marrow: magnetic resonance imaging appearances from birth to 5 years.

INTRODUCTION: Bone marrow (BM) assessment is an important aspect of paediatric MRI, with the marrow cavity visible on almost every clinical MR examination. In practice, however, assessment for marrow infiltration in paediatric patients can be challenging. Our aim was to review the MRI appearance of normal BM from 0 to 5 years. METHODS: Consecutive body MR examinations over 7 years were retrospectively reviewed in patients aged 0-5 years. Patients with anticipated BM abnormality were excluded. All patients had imaging of the spine and/or pelvis with T1-weighted (T1) ± T2 with fat saturation, post-contrast T1-weighted, diffusion-weighted or out-of-phase sequences. RESULTS: Nineteen patients were included: nine (47%) infants, 11 (58%) boys, mean age 18.2 months (range 1 day to 3 years and 10 months). On T1 imaging, 69% infant marrow sites and 24% in children >1 year were isointense, the remainder were hyperintense. One hundred per cent BM was T2 fat saturation hyperintense. Enhancement following contrast was seen in 16% of BM sites. Restricted diffusion was seen in 100% infant BM and 50% BM in children >1 year. On out-of-phase imaging, no signal loss was seen in infants, and 21% BM in children >1 year showed signal loss. CONCLUSION: Due to normal age-related differences in BM histology, MRI for marrow assessment in infants and young children can be misleading and may mimic marrow infiltration.

Diagnostic accuracy of combined coronary angiography and adenosine stress myocardial perfusion imaging using 320-detector computed tomography: pilot study.

OBJECTIVES: To determine the diagnostic accuracy of combined 320-detector row computed tomography coronary angiography (CTA) and adenosine stress CT myocardial perfusion imaging (CTP) in detecting perfusion abnormalities caused by obstructive coronary artery disease (CAD). METHODS: Twenty patients with suspected CAD who underwent initial investigation with single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) were recruited and underwent prospectively-gated 320-detector CTA/CTP and invasive angiography. Two blinded cardiologists evaluated invasive angiography images quantitatively (QCA). A blinded nuclear physician analysed SPECT-MPI images for fixed and reversible perfusion defects. Two blinded cardiologists assessed CTA/CTP studies qualitatively. Vessels/territories with both >50 % stenosis on QCA and corresponding perfusion defect on SPECT-MPI were defined as ischaemic and formed the reference standard. RESULTS: All patients completed the CTA/CTP protocol with diagnostic image quality. Of 60 vessels/territories, 17 (28 %) were ischaemic according to QCA/SPECT-MPI criteria. Sensitivity, specificity, PPV, NPV and area under the ROC curve for CTA/CTP was 94 %, 98 %, 94 %, 98 % and 0.96 (P < 0.001) on a per-vessel/territory basis. Mean CTA/CTP radiation dose was 9.2 ± 7.4 mSv compared with 13.2 ± 2.2 mSv for SPECT-MPI (P < 0.001). CONCLUSIONS: Combined 320-detector CTA/CTP is accurate in identifying obstructive CAD causing perfusion abnormalities compared with combined QCA/SPECT-MPI, achieved with lower radiation dose than SPECT-MPI. KEY POINTS: • Advances in CT technology provides comprehensive anatomical and functional cardiac information. • Combined 320-detector CTA/adenosine-stress CTP is feasible with excellent image quality. • Combined CTA/CTP is accurate in identifying myocardial ischaemia compared with QCA/SPECT-MPI. • Combined CTA/CTP results in lower patient radiation exposure than SPECT-MPI. • CTA/CTP may become an established imaging technique for suspected CAD.

Myocardial density analysis utilizing automated myocardial defect analysis software on resting 320-detector MDCT.

Cardiac CT myocardial perfusion is an emerging tool utilizing differences in myocardial density of ischemic compared to normal myocardium. We sought to document the contrast enhanced density profile of myocardial segments subtended by severely stenotic coronary arteries on rest (non stress) cardiac CT imaging, and compare the density with identical segments without ischemic disease. 100 cardiac CT studies were identified resulting in 25 normal patients, 37 with severe left anterior descending artery stenosis, 14 with severe left circumflex artery stenosis, and 24 with severe right coronary artery stenosis. The studies were reviewed on a workstation with dedicated myocardial analysis software. Left anterior descending artery ischemic segments (apical anterior and apical septal) measured 82.2 (±3) and 102 (±3) Hounsfield unit (HU) respectively comparing with non-ischemic segments 89 (±4) and 109 (±4) HU respectively (both P values 0.16). Left circumflex artery segments (basal anterolateral and mid anterolateral) demonstrated 80 (±4) and 76 (±4) HU respectively compared to non-ischemic segments, 89 (±4) and 87 (±4) HU (P value 0.13 and 0.07 respectively). Right coronary artery ischemic segments (basal inferoseptal and basal inferior) measured 104 (±3) and 105 (±3) HU respectively and these compared with non-ischemic segments, 102 (±4) and 105 (±4) HU respectively (P Value 0.69 and 0.94 respectively). Comparison of ischemic myocardial segments with non-ischemic segments demonstrated no significant difference in myocardial density. In prospectively acquired resting 320 multi detector CT, the myocardium subtended by severely stenotic vessels demonstrates no significant density difference compared with those supplied by vessels with no stenosis, confirming that myocardial ischaemia cannot be reliably detected on rest coronary computed tomography angiography by qualitative nor quantitative assessment.

Solid ectopic cervical thymus in neonates with thyroid agenesis.

We report a series of ectopic thymus glands as detected by sonography in infants with thyroid agenesis. The patients were children who underwent nuclear medicine and sonography for congenital hypothyroidism. Of the 12 patients with a diagnosis of thyroid agenesis over a 5-year period, 4 (33%) were shown to have ectopic thymic tissue. Although a cervical ectopic thymus has been previously reported, there is very little discussion of it occurring in conjunction with thyroid agenesis. This case series highlights the importance of recognition of ectopic thymic tissue when examining for thyroid tissue in the setting of congenital hypothyroidism.

Presence of accessory left atrial appendage/diverticula in a population with atrial fibrillation compared with those in sinus rhythm: a retrospective review.

Accessory left atrial appendages and atrial diverticula have an incidence of 10-27%. Their association with atrial fibrillation needs to be confirmed. This study determined the prevalence, number, size, location and morphology of accessory left atrial appendages/atrial diverticula in patients with atrial fibrillation compared with those in sinus rhythm. A retrospective analysis of 47 consecutive patients with atrial fibrillation who underwent 320 multidetector Coronary CT angiography (CCTA) was performed. A random group of 47 CCTA patients with sinus rhythm formed the control group. The presence, number, size, location and morphology of accessory left atrial appendages and atrial diverticula in each group were analysed. Twenty one patients had a total of 25 accessory left atrial appendages and atrial diverticula in the atrial fibrillation group and 22 patients had a total of 24 accessory left atrial appendages and atrial diverticula in the sinus rhythm group. Twenty-one atrial diverticula were identified in 19 patients in the atrial fibrillation group and 19 atrial diverticula in 17 patients in the sinus rhythm group. The mean length and width of accessory left atrial appendage was 6.9 and 4.7 mm, respectively in the atrial fibrillation group and 12 and 4.6 mm, respectively, in the sinus rhythm group, P = ns (not significant). The mean length and width of atrial diverticulum was 4.7 and 3.6 mm, respectively in the atrial fibrillation group and 6.2 and 5 mm, respectively in the sinus rhythm group (P = ns). Eighty-four % and 96% of the accessory left atrial appendages/atrial diverticula in the atrial fibrillation and sinus rhythm groups were located along the right anterosuperior left atrial wall. Accessory left atrial appendages and atrial diverticula are common structures with similar prevalence in patients with atrial fibrillation and sinus rhythm.

Coronary image quality of 320-MDCT in patients with heart rates above 65 beats per minute: preliminary experience.

OBJECTIVE: High heart rate may negatively influence the image quality of cardiac CT. The technical advances of 320-MDCT may overcome issues with poor image quality associated with high heart rate. This study aimed to evaluate the coronary image quality of 320-MDCT in patients with heart rates above 65 beats/min. MATERIALS AND METHODS: Patients who presented for cardiac CT were divided into two groups according to heart rate, either greater than 65 beats/min or less than or equal to 65 beats/min. Two radiologists were blinded to the patient groups and evaluated images of 15 coronary artery segments per patient using 320-MDCT with consensus agreement. The image quality was scored subjectively as 1 or 2 (diagnostic quality) or 3 (poor quality and nondiagnostic). RESULTS: There were no statistically significant differences between the two groups in terms of age, sex, and body mass index (p > 0.05). The median heart rate was 70 beats/min (range, 67-110 beats/min) for the group with heart rate greater than 65 beats/min and 60 beats/min (range, 48-65 beats/min) for the group with heart rate less than or equal to 65 beats/min (p < 0.001). In patients with heart rates greater than 65 beats/min, diagnostic quality images (scores of 1 or 2) were obtained in 95.6% of the analyzed segments, compared with 96.9% in the group with heart rate less than or equal to 65 beats/min (p = 0.7). CONCLUSION: Our initial evaluation suggests that coronary artery images of diagnostic quality can be obtained using 320-MDCT in most patients with heart rates greater than 65 beats/min, in percentages similar to those for patients with heart rates less than or equal to 65 beats/min. This finding may be the result of the inherent image acquisition and reconstruction technique of 320-MDCT.

Malignant pheochromocytoma metastasis to the breast shown on I-123 MIBG scan.

A 36-year-old woman was referred to our department for I-123 metaiodobenzylguanidine (MIBG)-SPECT/CT scan 3 years after surgical excision of pheochromocytoma. She was referred due to recurrence of her symptoms as well as raised urinary catecholamines. Review of I-123 MIBG scan revealed multiple MIBG-avid metastatic lesions. Most of these were bony lesions, however, there were also 2 soft tissue lesions in the left breast. She subsequently underwent ultrasound-guided fine-needle aspiration of the left breast lesions. Fine-needle aspiration revealed cytologic changes consistent with pheochromocytoma. There has only been 1 previous reported case of pheochromocytoma metastasizing to the breast. This is the first case in which the metastasis was detected by I-123 MIBG scan.

Comparison of 4 cm Z-axis and 16 cm Z-axis multidetector CT perfusion.

OBJECTIVE: The aim of the study was to compare 4 cm with 16 cm Z-axis coverage in the assessment of brain CT perfusion (CTP) using. 320 slice multidetector CT METHODS: A retrospective non-randomised review of CTP performed on MD320 CT between September 2008 and January 2009 was undertaken. Two experienced readers reviewed the studies along with the 4 cm and 16 cm Z-axis CTP image data set. The outcome parameters assessed were the extent of the original finding, any additional findings and a change of diagnosis. RESULTS: 14 out of 27 patients were found to have abnormal CTP (mean age 58.1 years, 9 male). The 16 cm Z-axis increased the accuracy of the infarct core in 78% and ischaemic penumbra quantification in 100% of the cases. It also diagnosed additional infarcts in the same vascular territory in 28% of cases and in a different vascular territory in 14%. CONCLUSIONS: The increased field of view with MD320 better defines the true extent of the infarct core and ischaemic penumbra. It also identified other areas of infarction that were not identified on the 4 cm Z-axis.

Image quality of coronary 320-MDCT in patients with atrial fibrillation: initial experience.

OBJECTIVE: Noninvasive coronary angiography has generally been contraindicated in patients with atrial fibrillation because of the difficulty in synchronizing an irregular heartbeat with table gantry movement. The objective of this study was to evaluate and compare the quality of 320-MDCT images obtained in patients with atrial fibrillation and in a control group of patients in sinus rhythm. MATERIALS AND METHODS: Two reviewers were blinded to the patient groups and evaluated images of 15 coronary artery segments for each patient using 320-MDCT. The images were printed on glossy paper and scored subjectively as 1 or 2, meaning of diagnostic quality, or 3, meaning poor quality. RESULTS: No statistical difference between the groups was noted in patient age: The mean age of the patients with atrial fibrillation was 67 years (age range, 52-82 years) and that of the patients in sinus rhythm was 59 years (36-86 years) (p = 0.3). Scores of 1 and 2 (diagnostic quality) were assigned to 100% in sinus rhythm and 96% in atrial fibrillation (p < 0.05). Scores of 3 were seen only in the atrial fibrillation group (7/175, 4%). Segment 15, the distal circumflex artery, was the segment that was most frequently assigned a score of 3 (2/7, 28.6%). A discrepancy in the two reviewers' scores was seen in 25 segments (7%), requiring joint consensus. The segments that most frequently required consensus reading were segments 12 and 15. The overall mean image quality score for all three coronary arteries in atrial fibrillation was 1.25 +/- 0.47 (SD) and 1.08 +/- 0.26 in sinus rhythm (p < 0.001). The median effective dose was 19.28 and 13.55 mSv in the atrial fibrillation and sinus rhythm groups, respectively. CONCLUSION: The analysis of our initial experience shows that imaging in patients with atrial fibrillation is possible using 320-MDCT, with images of most segments obtained being of diagnostic quality. Segment 15 was the most difficult to see on 320-MDCT because of the small caliber of the vessel; poor visualization of that segment mostly occurred in the setting of a dominant right coronary arterial system.

Efficacy of milk versus water to reduce interfering infra-cardiac activity in 99mTc-sestamibi myocardial perfusion scintigraphy.

OBJECTIVE: Interference from infra-cardiac radionuclide activity prevents accurate interpretation of true myocardial perfusion. The study aim was to compare the efficacy of milk versus water in reducing infra-cardiac activity in myocardial perfusion scintigraphy. METHODS: We prospectively randomized 198 patients undergoing stress-rest (99m)Tc-sestamibi SPECT with exercise or pharmacological stress to drink 300 ml of water or milk prior to imaging. A semi-quantitative grading of the relative intensity of infra-cardiac activity compared to the myocardial activity and a qualitative assessment of the effect on the overall interpretation was performed. RESULTS: For stress images, there was no infra-cardiac activity in 37.9%, less intense infra-cardiac activity in 40.8%, equal in 11.7% and greater than infra-cardiac activity in 9.7% with milk, compared with 20.0%, 49.5%, 20.0% and 10.5%, respectively, with water (P=0.038). For rest images, there was also less intense infra-cardiac activity with milk compared to water (P=0.014). However, no change in subsequent image interpretation was seen. CONCLUSION: Administration of milk resulted in a significant decrease in the intensity of infra-cardiac activity compared to water. However, this did not translate into an improvement in image interpretation.