The role of Computed Tomography Pulmonary Angiography in the diagnosis of pulmonary embolisms

This blog will discuss the use of computed tomography pulmonary angiography (CTPA) in patients suspected of having pulmonary embolism (PE) with evidence from relevant literature. It is an area of imaging that is of interest to me because I find the heart a fascinating organ to study.
PE is a blood clot in the blood vessels that carry blood from the heart into the lungs which can be deadly if not caught in time. The clot in the legs is known as deep vein thrombosis (DVT) (Morley et al, 2015). Symptoms include chest pain, shortness of breath and coughing up mucus or blood which can be caused by conditions such as cancer, heart failure, pregnancy and weakness in the wall of a blood vessel (NHS Choices, 2015). Other than CTPA, there are other diagnostic imaging procedures undertaken in order to diagnose PE in secondary care. These include chest x-ray, ventilation-perfusion scan, electrocardiography and lower limb compression venous ultrasound (National Institute of Health and Care Excellence, 2015a).
The National Institute for Health and Care Excellence (NICE, 2015b) guidelines say that patients suspected of having PE have CTPA immediately or are given anticoagulant therapy if it is not available immediately. In the case of pregnancy, contrast allergy or severe renal dysfunction the recommended pathway is ventilation-perfusion scan. This follows the review undertaken by Condliffe (2016), where first line investigation method after clinical examination was CTPA.
According to Walen et al. (2016) the specificity value of CTPA ranges between 81% and 98%, which makes it very valuable in excluding PE. However, the sensitivity values range from 60% to 100% which is a significant difference. The literature they have used as evidence is quite old, dating back to 1993. However, this is not discussed further as the aim of this study was to examine the diagnostic value of CTPA by influencing the behaviour of referrers. They explained that documenting Wells scores and D-dimer test scores on the request form increased the diagnostic yield from 23 % to 29.6 %. This is an important factor to consider. Research into diagnostic protocols of PE in the UK could be useful as this study was conducted in the Netherlands.
According to Mortensen and Gutte (2014) the sensitivity of CTPA was recorded to be 94 % and specificity value as 93 % using various sources as evidence. However, the authors have used sources that are over 10 years old. Considering this was published in 2014, it raises the question of whether they failed to include more up to date research to confirm these values. Furthermore, the diagnostic accuracy of CTPA is confirmed by Laugharne et al. (2013) using sources from 2005. This reveals a trend that would suggest more recent research has not been undertaken. They also mention that no CTPA examination was undiagnostic suggesting that the use is valid. While this study was conducted in the UK, it may not be applicable to the wider population as the sample included only elderly patients with the majority being female. They also justify the use of CT due to its availability in hospitals.
There was some debate on the topic of overdiagnosis and the impact on patients and healthcare providers. According to Wiener et al. (2013) small blood clots do not pose a significant risk and therefore do not need treatment. However this is challenged by Quantrill (2013), as he cites Wiener as acknowledging the drop in mortality by 3% after the introduction CTPA in diagnostic protocols. It is important to mention that Wiener used data on the trends in the US and this may not be generalisable to the UK or the rest of the world. Quantrill (2013) also points out that untreated PE can lead to severe health complications and death, highlighting the importance of offering treatment. The basis of Wiener’s (2013) argument is that the emboli are reabsorbed into the body without any clinical manifestations. Quantrill (2013) counters this by saying the effects of anticoagulation therapy is low enough to justify the benefit of giving it.
PE is treated with anticoagulant medicines and the amount of the medicine is measured regularly to check the dose is correct to prevent blood clots from reforming (NHS Choices, 2015).

 

Reference List:
Condliffe, R. (2016) Pathways for outpatient management of venous thromboembolism in a UK centre. Thrombosis Journal [online] 14 (1) [Accessed 14 November 2017].
Laugharne, M.J., Paravasthu, M., Preston, A., Hill, K.O. (2013) CT pulmonary angiography in elderly patients: Outcomes in patients aged > 85 years. Clinical Radiology [online] 68 (5) pp. 449-454 [Accessed 14 November 2017].
Mortensen, J., Gutte, H. (2014) SPECT/CT and pulmonary embolism. European Journal of Nuclear Medicine and Molecular Imaging [online] 41 (sup1) pp. 81-90 [Accessed 14 November 2017].
National Institute for Health and Care Excellence (2015a) Pulmonary embolism – Scenario: Managing suspected pulmonary embolism. Available at: https://cks.nice.org.uk/pulmonary-embolism#!scenario [Accessed 14 November 2017].
National Institute for Health and Care Excellence (2015b) Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. Available at: https://www.nice.org.uk/guidance/cg144/chapter/Key-priorities-for-implementation [Accessed 14 November 2017].
Quantrill, S.J. (2013) Risk-benefit ratio favours all pulmonary emboli, no matter how small. The British Medical Journal [online] 347 (5121) [Accessed 14 November 2017].
Walen, S., de Boer, E., Edens, M.A., van der Worp, C.A.J, Boomsma, M.F., van den Berg, J.W.K. (2016) Mandatory adherence to diagnostic protocol increases the yield of CTPA for pulmonary embolism. Insights into Imaging [online] 7 (5) pp. 727-734 [Accessed 14 November 2017].
Wiener, R.S., Schwartz, L.M., Woloshin, S. (2013) When a test is too good: how CT pulmonary angiograms find pulmonary emboli that do not need to be found. The British Medical Journal [online] 347 (7915) [Accessed 14 November 2017].

 

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Exploring imaging methods used in the detection of hepatocellular carcinomas

This week’s blog will focus on examining the detection of hepatocellular carcinoma (HCC) on patients with cirrhosis. It is inspired by last week’s lecture on imaging the hepato-biliary system.

According to The European Association of the Study of the Liver (EASL) (2012), HCC is the sixth most common cancer worldwide and the third most common cause of cancer related death. It develops from cells in the liver called hepatocytes hence why it is called a primary cancer. It is also more common in men than women and the risk increases with age, the peak being at the age of 70 (Cancer Research UK, 2015). Ethnicity is also a factor as the mean age of tumour manifestation is significantly younger within Asian and Black African population in the world. It also has a different pattern of occurrence in the world with the highest incidence rates found in East Asia, sub-Saharan Africa and Melanesia. 85 % of the cases in the world are found in these regions (EASL, 2012). Cirrhosis is a major risk factor, which is why adults with cirrhosis are offered 6-monthly surveillance for HCC (National Institute for Health and Care Excellence, 2017). Long-term survival is predicted by tumour stage at diagnosis, which is why early detection and accurate diagnosis is essential (Farrell et al. 2017; Cross et al., 2015).

Finding the best suited imaging technique for detection and characterisation of liver lesions on the background of cirrhotic liver is still a challenge (Kurucay et al. 2017). Farrell et al. (2017) did a review of the recall surveillance program for HCC detection in cirrhotic patients in a tertiary-referral centre in the UK. They acknowledge the lack of strong evidence for the efficacy of surveillance programs for HCC. This contradicts the guidelines published by the EASL (2012) which state it being cost-effective and helpful in excluding some patients from further surveillance. It is also not in line with NICE guidelines (2017) which recommend ultrasound surveillance, as HCC can remain asymptomatic while it advances. The reason behind the statement by Farrell et al. (2017) is most likely the lack of organisational support for surveillance programs and the poor provision of the service they found in their study. They continue to say that there is significant benefit to this program, provided they are given the same support as screening programs for other diseases such as breast and colon cancer (Farrell et al. 2017).

There is evidence in literature to say that accurate diagnosis requires contrast-enhanced CT and dynamic MRI with gadolinium (Kurucay et al. 2017; Hennedige and Venkatesh, 2012; EASL, 2012). While a biopsy was needed before, now radiological method is acceptable for diagnosis, provided there are imaging characteristics present (Hennedige and Venkatesh, 2012). This is ideal from patient management perspective as they do not need aftercare and are able to leave after the procedure.

The significant marker seems to be the vascular pattern of the tumour and this requires contrast-enhanced imaging methods (Hennedige and Venkatesh, 2012; EASL, 2012). The European Association of the Study of the Liver (2012) recommends the following guidelines in order to diagnose HCC. Lesions greater than 1 cm with a typical vascular pattern on dynamic contrast enhanced CT or MR should be treated as HCC. If a lesion has an atypical vascular pattern then further imaging is required for diagnosis. However, if a lesion is smaller than 1 cm with atypical vascular pattern then next step is to do a biopsy or an enhanced surveillance with MRI or CT. Lesions greater than 2 cm with atypical vascular patterns may be considered as HCC, provided the level of alpha-fetoprotein is above 200 ng/ml (AFP). High level of AFP is a strong indication of the presence of HCC.

Here, two articles discussing the diagnostic accuracy of CT and MRI for HCC, will be examined. The first one is a review by Kurucay et al. (2017), which examines the imaging parameters derived from perfusion CT (PCT) and gadoxetic acid-enhanced MRI in patients with HCC. The review was done in at one site in Germany with 36 cirrhotic patients with a diagnosis of HCC-suspected liver lesions. There were 67 lesions in total between the 36 patients. Perfusion CT quantified the blood flow within the liver with values for arterial liver perfusion (ALP), mean/max blood flow (BF), blood volume (BV), portal venous perfusion (PVP) and hepatic perfusion index (HPI). They found that HCC is associated with high HPI (> 96 %) and high values of BF in the tissue. Hennedige and Venkatesh (2012) agree with this, saying PCT quantifies arterial flow in the liver and can show the perfusion parameters, which differ significantly from between HCC tissue and normal liver parenchyma.

With regards to MRI, Kurucay et al. (2017) showed that six out of 67 HCCs were missed in T1 weighted images. 59 of the 67 lesions were detected in hepato-biliary phase images; 11 of the 67 lesions were missed on fat-saturated T2 weighted images. The conclusion showed that information from all applied imaging sequences were needed to equal the sensitivity of PCT. PCT also made clear the margins of the tumours, due to the high HPI value. Hennedige and Venkatesh (2012) agree and say that HCC has variable appearances on MRI. It seems to support the results found in the Kurucay et al (2017) study and can explain, why some lesions were missed in certain sequences. Hennedige and Venkatesh (2012) also add that diffusion-weighted imaging may be particularly useful in initial screening, as 70-95 % of lesions appear hyperintense.

The readers used in the study by Kurucay et al (2017) had the combined experience of more than 24 years in reading oncological CTs and MRIs. This was divided, with one reader having 4 years of experience and the other had more than 20 years. They may have done this to compare the effect of experience on lesion detection and characterisation, however they did not mention this in the article. It was mentioned that there were some disagreement with seven cases, however they were resolved in the end. The disagreement only occurred with the MRI scans and the steps that lead to the agreement were not explained. It would have been beneficial to include that information as it could be useful in managing reporting workload effectively within clinical imaging departments.

Kurucay et al. (2017) used only Siemens equipment with both CT and MRI, which suggests that results may differ between manufacturers. This means further studies need to be done with other equipment to compare their performance. The information is useful when departments consider purchasing new scanners. The MRI scanners used had different strength of magnets; one being 1.5 Tesla (T) and the other 3.0 T. This could have had an impact on the results as well. Also with regards to patient management the CT protocol was more patient-friendly, requiring only two scans with one injection of contrast. The MRI protocol included GRE T1-weighted, axial respiratory gated T2-weighted, diffusion weighted and fat suppressed T1 weighted VIBE sequences before the contrast was given. This was followed by four fat suppressed T1 weighted VIBE sequences. The time used is extensive and with issues experienced in these scans, such as claustrophobia and sensitivity to the noise of the machine, it is not the most patient friendly option. However, it is an recommended option because of the use of non-ionising radiation. The dose received from PCT varied between 9 and 14 mSv depending on the scan length. This is significant amount as it is around the range of CT scan of the whole spine, which is 10 mSv (Public Health England, 2011).

Sadly the 3 year survival rate of HCC can be as low as 10 %. Farrell et al. (2017) review showed that 16 of the 22 patients diagnosed with HCC died by June 2016. The review was conducted between 2009 and 2013. Low survival rates coupled with the rising incidence rates of HCC, shows the need for research in improving screening methods as well as diagnostic imaging technology for early detection (EASL, 2012).

 

 

Reference List:

Cancer Research UK (2015) Liver cancer – types. Available at: http://www.cancerresearchuk.org/about-cancer/liver-cancer/types [Accessed 09 November 2017].

Cross, T.J., Villaneuva, A., Shetty, S., Wilkes, E., Collins, P., Adair, A., Jones, R.L., Foxton, M.R., Meyer, T., Stern, N., Warshow, U., Khan, N., Prince, M., Khakoo, S., Alexander, G.J., Khan, S., Reeves, H., Marshall, A., Williams, R. (2015) A national survey of the provision of ultrasound surveillance for the detection of hepatocellular carcinoma. BMJ Journals [online] 7 (2) [Accessed 09 November 2017].

European Association for the Study of the Liver (2012) EASL Clinical Practice Guidelines on the management of hepato-cellular carcinoma. Available at: http://www.easl.eu/research/our-contributions/clinical-practice-guidelines/detail/management-of-hepatocellular-carcinoma-easl-eortc-clinical-practice-guidelines/report/4 [Accessed 12 November 2017].

Farrell, C., Halpen, A., Cross, T.J.S., Richardson, P.D., Johnson, P., Joekes, E.C. (2017) Ultrasound surveillance for hepatocellular carcinoma: service evaluation of a radiology-led recall system in a tertiary-referral centre for liver diseases in the UK. Clinical Radiology [online] 72 (4) p 338.e11 – 338.e17 [Accessed 12 November 2017].

Hennedige, T., Venkatesh, S.K. (2012) Imaging of hepatocellular carcinoma: diagnosis, staging and treatment monitoring. Cancer Imaging [online] 12 (3) pp. 530-547 [Available 12 November 2017].

Kurucay, M., Kloth, C., Kaufmann, S., Nikolau, K., Bosmuller, H., Horger, M., Thaiss, W.M. (2017) Multiparametric imaging for detection and characterization of hepatocellular carcinoma using gadodetix acid-enhanced MRI and perfusion-CT: which parameters work best? Cancer Imaging [online] 17 pp. 1-8 [Accessed 12 November 2017].

National Institute for Health and Care Excellence (2017) Liver disease quality standard [QS152]. Available at: https://www.nice.org.uk/guidance/qs152/chapter/Quality-statement-4-Surveillance-for-hepatocellular-carcinoma [Accessed 12 November 2017].

Public Health England (2011) Ionising radiation: dose comparisons. Available at: https://www.gov.uk/government/publications/ionising-radiation-dose-comparisons/ionising-radiation-dose-comparisons [Accessed 12 November 2017].

 

 

Imaging of conditions related to sickle cell disease (SCD)

This week’s blog will focus on exploring imaging methods used to identify conditions resulting from sickle cell disease (SCD).

According to National Institute for Health and Care Excellence (NICE, 2016) sickle cell disease is a mutation in the haemoglobin chain. This changes the shape of the red blood cell. These cells can then form clusters and block blood vessels. The shape of the red blood cells is designed to navigate blood vessels with efficiency and this mutation interferes with this process.

It is a genetic disease, which develops as a result of inheriting an abnormal haemoglobin variant from one parent and sickle haemoglobin from another. A person can also be a carrier of sickle cell trait by inheriting the sickle cell haemoglobin from one parent and a normal haemoglobin gene from the other. The highest prevalence is amongst people of Black African and Caribbean descent (NICE, 2016).

Sickle cell disease is diagnosed through tests such a full blood count, reticulocyte count, and blood film (NICE, 2016). This condition also causes a person to be susceptible to further health complications. These include dactylis, stress fracture and vertebral collapse among others (NICE, 2016; Almeida and Roberts, 2005).

The consideration for diagnostic imaging comes when looking at the effect of SCD on other organ systems. According to Almeida and Roberts (2005) bone involvement is one of the common presentations of SCD with conditions such as osteomyelitis. They also mention that diagnosing osteomyelitis with plain film x-rays is not useful as findings are non-specific. Imaging methods such as MRI are more useful especially with the use of contrast agent such as gadolinium. However, they assert that clinical observations and bone biopsy is relied on more than any single imaging method.

According to Bires et al. (2015), the imaging method deemed superior is radionuclide imaging (RNI). Although it is an American publication and guidelines may differ from those in the UK, it is helpful to mention the different methods used in other countries. It is specifically a three-phase bone scan with a sensitivity of over 90 percent. This is very good rate considering it identifies the condition within two days from the early onset of symptoms.

The use of RNI is corroborated by Dinh et al. (2008) and Almeida and Roberts (2005). The study by Dinh et al. (2008) discusses diagnosis of osteomyelitis underlying diabetic foot ulcers. They recognise the challenge of diagnosis with this condition. According to Almeida and Roberts (2005) MRI is more sensitive with patients where it is not suspected. With cases where it is clinically suspected, PET is only slightly less sensitive but is has a higher specificity of 93 percent compared to 81 percent with MRI.

Magnetic resonance imaging (MRI) is mentioned as a good alternative for RNI by both Dinh et al. (2008) and Bires et al. (2015) to eliminate the risk of radiation to paediatric patients. However, MRI takes time and the patient needs to be co-operative, which may not be possible with children. Additional aspect to consider is the study by Dinh et al. (2008), only included four trials using MRI which does not necessarily mean it is a reliable method.

The challenge seems to be identifying osteomyelitis with the presence of other conditions. This is the reason why clinical findings coupled with blood tests and biopsy is the gold standard for diagnosis (Almeida and Roberts, 2005). Due to the complications resulting from SCD, research is essential in improving the specificity and sensitivity of these imaging methods.

 

 

Reference List

Almeida, A., Roberts, I. (2005) Bone involvement in sickle cell disease. British Journal of Haematology [online] 129 (4) pp. 482-490 [Accessed 04 November 2017].

Bires, A.M., Kerr, B., George, L. (2015) Osteomyelitis: An Overview of Imaging Modalities. Critical Care Nursing Quarterly [online] 38 (2) pp. 154-164 [Accessed 04 November 2017].

Dinh, M.T., Abad, C.L., Safdar, N. (2008) Diagnostic Accuracy of the Physical Examination and Imaging Tests for Osteomyelitis Underlying Diabetic Foot Ulcers: Meta-Analysis. Clinical Infectious Diseases [online] 47 (4) pp. 519-527 [Accessed 04 November 2017].

National Institute for Health and Care Excellence (2016) Sickle cell disease: Summary. Available from: https://cks.nice.org.uk/sickle-cell-disease#!backgroundsub [Accessed 04 November 2017].

DBT vs digital mammography

 This post will focus on one study comparing digital breast tomosynthesis and conventional 2D digital mammography in detecting different types of lesions in the breast tissue with a brief overview of breast cancer. 

According to Cancer Research UK (2017a) breast cancer is the most common cancer affecting females worldwide and particularly women between the ages of 65-69. The NHS Breast Screening Programme is targeted to women from age 50 to 70 with trials being done to see if the age range should be extended to 47-73. Participants outside the current screening age are recruited by sending a leaflet with information of the trial including the risks and benefits to ensure informed consent (Public Health England, 2015a).  

Digital breast tomosynthesis (DBT) is an imaging technique that differs from 2D digital mammography by taking a series of exposures at multiple angles and reconstructing the data into a 3D image of the breast tissue (Haq et al. 2015). The data can then be examined by blurring or removing the tissues overlying or underlying the plane and thus improve the visualisation of lesions (Public Health England, 2015b). This helps to avoid tumours being missed and further assessments that are unnecessary causing distress to patients (Haq et al. 2015).  

The study that will be discussed next is a multicentre retrospective reading study comparing the diagnostic accuracy of 2D vs DBT + 2D and 2D vs synthetic 2D + DBT. The women included were selected from six different centres including one for symptomatic patients. They looked at 7061 cases with 6021 cases being recalls and 1040 being women with family history called for the annual screening. The age range was 40-73 and all cases involved were women (Gilbert et al. 2015).

The design of the study is set up well to measure the validity of imaging methods because it includes patients who are suspected of having the abnormality through initial screening or family history (Ramlaul, 2010). With regards to sample size Gilbert et al. (2015) mentioned that 7000 cases would be enough to accurately compare the accuracy of these imaging methods. Power calculations to assess the sample size required here, are necessary (Ramlaul, 2010). This is was done by Gilbert et al. (2015) by saying each given cancer case would give a correct answer whether malignant or not from one of the imaging combinations examined. It was calculated so to allow statistical significance for subgroup analysis, which explains the high number of cases. The subgroups included women between the ages of 40-49 with family history, cancers presenting as soft tissue masses and cancers presenting as micro-calcifications. Consideration was given to type of DBT equipment used, however because DBT technology is still largely being developed, the options were limited. The choice of equipment was one that was well established at the time in 2010, which means this study done now, would perhaps give different results due to technological advancements.

Another issue compared was breast density, measured by readers and by software programmes. This was done at the time of the assessments prior to sending to trial office. The same scrutiny was not given to this aspect as to the imaging methods, however it was mentioned in the study as a secondary objective. According to Cancer Research UK (2017b) breast density is a risk factor , with increased density associated with higher risk of breast cancer. The image acquisition in this study for 2D images and DBT images were done without changing positioning of the patient to reduce differences in both images (Gilbert et al. 2015).

To assess the reliability of the results, the observer variability needs to be considered (Ramlaul, 2010). This was acknowledged in the study by doing a reader study comparing readers at different sites. One of the aspects considered was reader experience, which was shown not to impact significantly on recall rates or cancer detection, however reader fatigue and differences in local practices at different sites explains variation of the results (Gilbert et al. 2015).

In terms of patient dose, Gilbert et al. (2015) suggests using synthetic 2D images with DBT views to eliminate the use of 2D views by constructing 2D images from the DBT data sets and thus reduce patient dose.  The impact on workload is substantial with DBT as the reading and reporting times doubled with it. However Gilbert et al. (2015) justifies this by suggesting a reduction in recall rates would save resources.

The outcomes were measured for all three combinations against the gold standard, which was the verification through biopsy showing benign or malignant tumours. The results showed increase in specificity with using 2D and DBT combined but no significant increase in sensitivity. The study recognises the need for further research into long-term clinical outcomes and especially mentioned reduced mortality (Gilbert et al. 2015).

Reference List:  

Cancer Research UK (2017a) Breast cancer incidence (invasive) statistics. Available from: http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer/incidence-invasive#heading-Eleven [Accessed 24 October 2017].

Cancer Research UK (2017b) Breast cancer risk factors. Available from: http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer/risk-factors. [Accessed 24 October 2017].

Gilbert, F.J., Tucker, L., Gillan, M.G., Wilsher, P., Cooke, J., Duncan, K.A., Michell, M.J., Dobson, H.M., Lim, Y.Y., Purushothaman, H., Strudley, C., Astley, S.M., Morrish, O., Young, K.C., Duffy, S.W. (2015) TOMMY trial: A comparison of tomosynthesis with digital mammography in the UK NHS Breast Screening Programme. Health Technology Assessment [online] 19 (4) [Accessed 24 October 2017].

Haq, R., Lim, Y.Y., Maxwell, A.J., Hurley, E., Beetles, U., Bundred, S., Wilson, M., Astley, S., Gilbert, F.J. (2015) Digital breast tomosynthesis at screening assessment: are two views always necessary? British Institute of Radiology [online] 88 (1055) [Accessed 21 October 2017].  

Public Health England (2015a) Breast screening programme: overview. Available from: https://www.gov.uk/guidance/breast-screening-programme-overview [Accessed 24 October 2017].

Public Health England (2015b) Routine quality control tests for breast tomosynthesis (physicists) NHS Breast Screening Programme Equipment Report. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/488949/Breast_screening_1407_Physics_Tomo_QC_Protocol_Final_291215.pdf [Accessed 24 October 2017].

Ramlaul, A. (2010) Medical Imaging and Radiotherapy Research Skills and Strategies [online]. Revised ed. London: Churchill Livingstone Elsevier. [Accessed 24 October 2017].

Nephrogenic systemic fibrosis and the role of gadolinium-based contrast agents

This post will be focusing on the link between gadolinium-based contrast agents (GBCA) and nephrogenic systemic fibrosis (NSF). The areas discussed include what is NSF and how it affects the body, patient safety including guidelines to health professionals using GBCA as well as the theory on why gadolinium triggers the development of NSF.

NSF is a serious life-threatening condition that causes the connective tissue to become hardened and coarse. The on-set is usually 2 months after exposure to gadolinium however it can also take a few years to emerge (Thomsen et al. 2013). It mainly affects the skin however it can spread to other organs such as the heart, liver and muscle (Agarwal et al. 2008). It can also affect joint mobility to extent where wheel-chair use is necessary (Thomsen et al. 2013; Medicines and Healthcare products Regulatory Agency 2010).

The literature shows that the link between NSF and GBCAs was first discovered by Grobner with a study associated skin lesions with MR angiogram and end-stage renal disease (Kanal 2016; Thomsen et al. 2013; Marckmann et al. 2007). It is also a risk for pregnant patients, elderly, infants and neonates (Medicines and Healthcare products Regulatory Agency 2010). There is evidence to show differing levels of risk with different types of GBCA with some being of high risk and some being of low risk (Besheli et al. 2014; Medicines and Healthcare products Regulatory Agency 2010; Agarwal et al. 2008; Marckmann et al. 2007).

According to a study conducted by Schneider et al. (2013) none of the patients demonstrated symptoms of NSF, however they only one monitored the patients for 24 hours after a contrast-enhanced MRI scan. The contrast agent used was gadobenate dimeglumine and the risk is associated specifically with gadodiamide (Kanal 2016; Marckmann et al. 2007). This is due to its molecular structure as non-ionic linear chelates have weaker bonds to the gadolinium and thus will readily disassociate in the body (Thomsen et al. 2013). According to Kanal (2016) the likelihood of developing NSF increases with the severity of the renal impairment at time of using GBCA, with a remarkable portion of NSF patients having received it during an acute renal failure.

The relationship between GBCA and NSF is still unclear and requires further investigation. Gadolinium – ion is toxic to the body and requires other chemical compounds in order to be safe for administration (Thomsen et al. 2013). One possible explanation is presented in the theory of transmetallation. It explains that longer biological half-life of GBCA leads to more of the gadolinium ions disassociating and depositing in the skeleton where it lays dormant until coming across molecules which trigger the development of NSF (Kanal 2016; Thomsen et al. 2013).

The current guidelines with respect to using GBCA is to screen the renal function of patients before administering GBCA and optimise the amount of contrast administered and avoid repeating examination within 7 days. It is not recommended to be used with pregnant patients unless absolutely necessary and halt breastfeeding for 24 hours after using high-risk GBCA (Medicines and Healthcare products Regulatory Agency, 2010).

The continuous review of literature is essential for radiographers working in MRI to provide best evidence-based care particularly with vulnerable patients such as elderly and neonates.

 

Reference List:

Agarwal, R., Brunelli, S.M., Williams, K., Mitchell, M.D., Feldman, H.I., Umscheid. C.A. (2008) Gadolinium-based contrast agents and nephrogenic systemic fibrosis: a systemic review and meta-analysis. Nephrology Dialysis Transplantation [online] 24 (3) pp. 856-863 [Accessed 11 October 2017].

Besheli, D.L., Aran, S., Shaqdan, K., Kay, J., Abujudeh (2014) Current status of nephrogenic systemic fibrosis. Clinical Radiology [online] 69 (7) pp. 661-668 [Accessed 09 October 2017].

Kanal, E. (2016) Gadolinium based contrast agents (GBCA): Safety overview after 3 decades of clinical experience. Magnetic Resonance Imaging [online] 34 (10) pp. 1341-1345 [Accessed 09 October 2017].

Marckmann, P., Skov, L., Rossen, K., Heaf Goya, J., Thomsen, H.S. (2007) Case-control study of gadodiamide-related nephrogenic systemic fibrosis. Nephrology Dialysis Transplantation [online] 22 (11) pp. 3174-3178 [Accessed 09 October 2017].

Medicines and Healthcare products Regulatory Agency (2010) Gadolinium-containing contrast agents: new advice to minimise risk of nephrogenic systemic fibrosis. London: Medicines and Healthcare products Regulatory Agency. [Accessed 11 October 2017] Available at: https://www.gov.uk/drug-safety-update/gadolinium-containing-contrast-agents-new-advice-to-minimise-the-risk-of-nephrogenic-systemic-fibrosis

Schneider, G., Schurholz, H., Kirchin, M.A., Bucker, A., Fries, P. (2013) Safety and adverse effects during 24 hours after contrast-enchanced MRI with gadobenate dimeglumine (MultiHance®) in children. Pediatric Radiology [online] 43 (2) pp. 202-211 [Accessed 09 October 2017].

Thomsen, H.S., Morcos, S.K., Almen, T., Bellin, M., Bertolotto, M., Bongartz, G., Clement, O., Leander, P., Heinz-Peer, G., Reimer, P., Stacul, F., van der Molen, A., Webb, J. (2013) Nephrogenic systemic fibrosis and gadolinium-based contrast media: updated ESUR Contrast Medium Safety Committee guidelines. European Radiology [online] 23 (2) pp. 307-318 {Accessed 09 October 2017].

Imaging of renal cell carcinomas

I have been interested in learning more about pathologies and how they can be best diagnosed with imaging modalities. In this blog post I will focus on detection and identification of renal cell carcinomas. Renal cell carcinoma (RCC) is the most common type of renal tumour in adults (Sankineni et al. 2016). The first-line imaging method to differentiating renal lesions in general is CT (Krishna et al. 2017). However there is evidence from other studies showing that MRI is excellent in characterising renal lesions. The reason why CT is more popular method is it being more accessible, cost effective and better tolerated by patients (Krishna et al. 2017).

There are different types of RCCs and the two discussed mostly in these journal articles were clear cell RCC and renal papillary carcinoma. The most common of the two is clear cell RCC which is 60-65 % of all RCC while renal papillary carcinoma is 10-15 % (Sankineni et al. 2016). According to Sankineni et al. (2016) the primary imaging method used in detecting lesions in the kidney worldwide is ultrasound (US) due to it being fast, can be easily repeated and low cost. However CT is the primary method in imaging the lesions and is more reliable when imaging lesions that are smaller as their detection rate is lower on US (Krishna et al. 2017).

MRI is used when there is contrast allergy or other contra-indications that do not allow CT imaging (Sankineni et al. 2016). It is also used to supplement the imaging done with CT and it is especially useful in detecting whether it is renal papillary carcinoma. According to a study of 79 patients with papillary carcinomas that were imaged with CT and MRI showed that MRI was better at enhancing the lesions (Couvidat et al. 2014). It means that although CT is the primary method of imaging, MRI would be more suitable to diagnose renal papillary carcinomas. It is also favoured method for young patients due to dose considerations of CT (Krishna et al. 2017).

Reference List

  1. Sankineni, S., Brown, A., Cieciera, M., Choyke, P.L. and Turkbey, B. (2016) Imaging of renal carcinoma. Urologic Oncology: Seminars and Original Investigations [online] 34 (3) pp. 147-155 [Accessed 27 September 2017].  
  2. Couvidat, C., Eiss, D., Verkarre, V., Merran, S., Correas, J.-M., Mejean, A. and Helenon, O (2014) Renal papillary carcinoma: CT and MRI features. Diagnostic and Interventional Imaging [online] 95 (11) pp. 1055-1063 [Accessed 27 September 2017].
  3. Krishna, S., Murray, C.A., McInnes, M.D., Chatelain, R., Siddaiah, M., Al-Dandan, O., Narayanasamy, S. and Schieda, N. (2017) CT imaging of solid renal masses: pitfalls and solutions. Clinical Radiology [online] 72 (9) pp. 708-721 [Accessed 27 September 2017). 

 

 

Introduction

Hello, my name is Mariam and I am a 26-year old student living in Bristol. I am studying Diagnostic Imaging at UWE Bristol. I am originally from Somalia and was born in Mogadishu. My family fled Somalia due to the civil war in 1993 and settled in Finland. I grew up in Finland and as a result can speak Finnish fluently. I have a big family with 5 sisters and 2 brothers.

Before choosing to study Diagnostic Imaging, I started studying nursing in Finland. I realised after one year that nursing was not what I wanted and decided to drop out and move to the UK to be with my family. My family had moved there the start of my course.

In my spare time I love to watch science fiction and fantasy tv series and films. My favourite at the moment is the Expanse l, which is about humans colonising other planets in the solar systems such as Mars. I am also a huge Star Wars fan. Below is a picture of me.

IMG_0757

I will be writing more on my research related to topics discussed in lectures about diagnostic imaging theory.

Thank you for reading