Fatima, Nosheen

Zaman, Maseeh Uz

English

eCommons@AKU

eCommons@AKUDepartment of Radiology Medical College, PakistanApril 2017Nuclear Medicine Imaging in Emergency Roomand Priority Clinical Decision MakingNosheen FatimaAga Khan University, nosheen.fatima@aku.eduMaseeh Uz ZamanAga Khan University, maseeh.uzzaman@aku.eduFollow this and additional works at: https://ecommons.aku.edu/pakistan_fhs_mc_radiolPart of the Radiology CommonsRecommended CitationFatima, N., Zaman, M. U. (2017). Nuclear Medicine Imaging in Emergency Room and Priority Clinical Decision Making. Journal ofthe College of Physicians and Surgeons Pakistan, 27(4), 197-199.Available at: https://ecommons.aku.edu/pakistan_fhs_mc_radiol/225In the present era, medical imaging (both morphologicaland functional) plays a significant role in the managementof critically ill patients in the emergency room (ER).There is general tendency that the healthcare providersin ER are traditionally trained to rely on medical imaging,particularly morphological (radiological) procedures. Themajor challenge for ER doctors is to find out anappropriate balance between over-testing in fear ofmissing diagnosis or under-testing in climate wherefinancial, legal, and insurance impacts speak high. Thereis a real need to sensitize the ER physicians about theexisting role of Nuclear Medicine (NM) in certain criticalconditions, either as first-line or complementary imaging.The proven higher sensitivity and evolving cost effective-ness of NM procedures have resulted in major paradigmshift about its clinical utility in certain acute conditions,where anatomical imaging is either silent or hasconcerns of allergic and contrast reaction as there isnothing like contrast reaction in NM procedures.1Unfortunately, over the last two decades NM could notfind fair space in major guidelines of emergency imagingdue to diffusion of new generation computed tomography(CT) and magnetic resonance imaging (MRI) modalities,dominating the radiological societies. However, recentlya separate section of NM imaging has been added in thepractical guides of emergency imaging.2 Emergencyradiology is an established entity in United States andgenerally considered an active facility for 24 hours a dayand seven days a week for any tertiary care hospital allaround the world, but statistics of NM emergencyfunctionality is not remarkable. As per published data of1995, only 29% of NM centers in United Kingdom wereoffering on-call services,3 with no recent updates instatistics till to date. In Pakistan, there are a fair numberof NM centers, both in private and public sectorsprimarily under the umbrella of Pakistan Atomic EnergyCommission (PAEC) in all four provinces. However, tothe best of authors' information only 1-2 NM privatecenters are offering on-call services on 24/7 basis. Thebasic reason of significant underutilization is limitedaccess of NM services in ER of many hospitals. Ideally,NM services should be available round-the-clock, butthe cost implication of 24/7 active NM services is huge.It can be justified on concrete ground of emerging factsof cost effectiveness of NM with better patient outcome.4The Society of Nuclear Medicine and Molecular Imaging(SNMMI) and European Association of Nuclear Medicine(EANM) defined and released the revised secondversion of “Guideline for Tele Nuclear Medicine” in 2013for NM interpretation and consultation remotely from thearea where the study has been originally acquired.5 Themain indications to provide on-call NM services duringoff-peak hours or for routine cases in areas where NM isunderserved or if center is absolutely dependent on oneNM consultant who may happen to be out of station.These guidelines comprehensively discuss the funda-mental requirements for functionality of Tele NM services,like work station system specification, mandatoryrequirement of patient's information on reporting end,data confidentiality, and above all, importance of hospitalcommunication policy between reading and orderingphysicians in cases of panic results.6,7The utility of NM services in acute conditions can bedivided into the indications in ER, and indications otherthan ER for priority decisions.NM Indications in ER include lung ventilation andperfusion scintigraphy (V/Q study) for pulmonaryembolism (PE), resting myocardial perfusion imaging(MPI) for acute coronary syndrome (ACS), tagged redblood cell (RBC) imaging for lower gastrointestinal (GI)bleed and testicular scintigraphy for patients presentedto ER.The V/Q study is the most common NM indication in ERfor PE. However, computed tomography pulmonaryangiography (CTPA) has essentially replaced the V/Qstudy for diagnosis of PE; but due to the provensensitivity and feasibility, many societies and guidelinesstill prefer V/Q study as the preferred choice in PE.8Irrespective of choice, the indication of imaging in PE ismainly depend on pre-test clinical probability based onvarious models. The major challenge in diagnosis of PEis lack of satisfactory gold standard which posesdifficulties in assessment of accuracy of diagnostic tests.A follow-up is considered best available benchmark toJournal of the College of Physicians and Surgeons Pakistan 2017, Vol. 27 (4): 197-199 197EDITORIALNuclear Medicine Imaging in Emergency Roomand Priority Clinical Decision MakingNosheen Fatima and Maseeh uz ZamanSection of Nuclear Medicine and PET/CT Imaging Services,Department of Radiology, Aga Khan University Hospital,Karachi.Correspondence: Dr. Nosheen Fatima, Assistant Professor,Section of Nuclear Medicine and PET/CT Imaging Services,Department of Radiology, Aga Khan University Hospital,Karachi.E-mail: nosheen.fatima@aku.eduReceived: May 04, 2017;   Accepted: May 05, 2017.rule out recurrence of PE or making alternativediagnosis.9 Depending on the availability of V/Q or multi-detector CT (MDCT), the imaging is indicated in all pre-test clinical probabilities in hemodynamically stablepatients except low probability with non-critical D-dimerwhile V/Q is recommended as second line of indicationnext to echocardiography due to feasibility preferenceover MDCT in hemodynamically unstable patients. V/Qstudy has higher sensitivity and specificity comparedwith the MDCT.10 V/Q study is 99% effective in 50% ofcases where CTPA is contraindicated. There is 35-40%reduction in patient's absorbed dose who has a V/PSPECT protocol as compared to MDCT,11 andconsidered preferred imaging choice in suspicious of PEin pregnancy with 4% reduction in maternal radiationdose. However, there has been a debate about fetaldose and large body of data favors that fetal radiationabsorbed dose is either equivalent or lesser than MDCTin V/Q study during first trimester. However, this wouldbe increased thereafter which could be optimized eitherusing half dose protocol with perfusion first or two-dayprotocol, if ventilation study is need.12One of major diagnostic challenges for ER doctors is apatient with persistent chest pain having negative sets ofcardiac enzymes and equivocal ECG changes. A restingmyocardial perfusion imaging (MPI) has a proven >99%negative predictive value (NPV) to rule out acutecoronary syndrome (ACS) with high degree ofconfidence and also predicts the high event-freesurvival, as well. The cost effectiveness of resting MPIalgorithm as a 'gatekeeper' to admission for patients withACS has been well documented in numerous trials.13,14By using resting MPI algorithm, patients with lowprobability can be identified and discharged safely.Tagged RBC scintigraphy is a very sensitive and non-invasive functional imaging modality to localize an activelower GI-bleed as low as 0.05-0.2 ml/minute, which is thelowest among other competitive modalities like contrastor CT angiography.8 In addition to localize sites of activeGI-bleeding, tagged RBC imaging also serves as gate-keeper for aggressive treatment (surgery or arterio-graphy) versus those who can be managed conservatively.Additionally, tagged RBC imaging either with SPECT orSPECT-CT provides useful supplemental anatomicalinformation that benefits patient management andimproves diagnostic accuracy. Due to proven sensitivityof 93%, a negative GI-bleed scan may obviate the needfor emergency arteriography with reported goodprognosis.15Testicular scintigraphy serves as gatekeeper in acutepainful scrotum to differentiate acute epididymoorchitisfor conservative management with testicular torsion tobe managed surgically with a sensitivity of 90-100% andspecificity of 89-98%, respectively. However, as perAmerican College of Radiology (ACR) AppropriatenessCriteria 2014, Doppler ultrasound is recommended to bethe first line imaging in painful scrotum due to limitationsof radiation, availability and false studies in testicularscintigraphy.16 Nevertheless, testicular scintigraphy isstill considered in equivocal Doppler studies prior tosurgical exploration.NM Acute Indications other than ER: Brain perfusionscintigraphy for brain death declaration, skeletalscintigraphy in acute bone insult, renal scintigraphy intransplant dysfunction, and hepatobiliary scintigraphy inacute cholecystitis or localization of bile leak are fewgood examples of NM indications other than ER; butconsidered critical indications, due to certain prioritydecisions, absolutely based on imaging results.Declaration of brain death has social, religious, legal,and ethical impacts. Brain perfusion scintigraphy may beperformed as an ancillary test in the evaluation ofpatients for brain death. In the scenario of organdonation, before patients' organs are harvested fordonation, declaration of death may have technicallimitations associated with clinical and electro-encephalographic assessments of brain activity inconditions like hypothermia, drug intoxication, and braininjury; and in patients where brain death may be theresult of criminal activity.17 Brain perfusion scintigraphyis simple, sensitive, specific, and reliable tool to confirmbrain death with a high level of confidence. Falsenegative studies can be minimized by adequate bolusinjection of isotope and reporting by experienced nuclearphysician.18Conventional radiography is the principal method ofinvestigation in patients with suspected acute skeletaltrauma. Skeletal scintigraphy has a proven highersensitivity in a window where plain x-ray is falselynegative prior to demineralization or to localize theunspecified fracture site and may be helpful in timelymanagement in certain traumatic or non-traumatic bonepain. Major role of skeletal scintigraphy in UK in timelydiagnosis and management of scaphoid fracture withsensitivity and specificity of 100% and 98%, respectively;when second imaging is negative after 14 days oftrauma.1 Other indications are occult fracture of pelvis orfemur, acute osteomyelitis, battered baby syndrome,chronic regional pain syndrome, stress fracture, shinsplint, and sports trauma. A negative skeletalscintigraphy excludes any bone insult, and plays majorrole in legal and insurance aspects of disputed accidentor military medicine cases.Renal transplant scintigraphy is usually performed toevaluate graft dysfunction in the first few days or first fewweeks after surgery, but it may also be performed inpatients who experience an acute deterioration of renalfunction months after successful transplantation. It canbe helpful for distinguishing conditions requiring surgicalmanagement like vascular or ureteral obstructionaffecting the transplant from those with parenchymalNosheen Fatima and Maseeh uz Zaman198 Journal of the College of Physicians and Surgeons Pakistan 2017, Vol. 27 (4): 197-199complications that can be managed conservatively likeacute tubular necrosis or acute rejection.17Hepatobiliary scintigraphy has high diagnostic accuracyin diagnosing acute cholecystitis (AC) and is consideredas an excellent second tier test for the diagnosis of ACin the work-up of indeterminate cases by sonography.Hepatobiliary scintigraphy is specific for localization ofbile leak in posttrauma and postsurgical cases.In addition to above indications, there are other acutescenarios where NM has proven its clinical efficacy likeinfection imaging for pyrexia of unknown origin (PUO),renal cortical imaging for suspected renal trauma or CSFleak studies.Nuclear medicine has been losing ground on the front ofimaging services in ER due to logistic, technical, andhuman-resource constraints and tendency of NMpersonnel towards fixed work hours. In order to provethe role of NM in acute conditions as a first line andalternative or complementary to conventional imaging,there is a dire need to change attitude towards on-callservice or to avail Tele NM option to be visible on clinicalscenario.REFERENCES1. McGlone BS, Balan KK. The use of nuclear medicinetechniques in the emergency department. Emerg Med J 2001;18:424-9.2. Joseph UA. Emergency imaging: A practical guide. J Nucl Med2016; 57:989-95.  3. O'Doherty MJ, Kettle AG, Bird NJ, Barrington SF, Wells CP,Coakley AJ. Home reporting for the nuclear clinician? NuclMed Commun 1995; 16:1054-7.4. Eustance C, Carter N, O'Doherty M, Coakley AJ. Effect onpatient management of a weekend 'on-call' nuclear medicineservice. Nucl Med Commun 1994; 15:388-91.5. Parker JA, Christian P, Jadvar H, Sattler B, Wallis JW. TheSNMMI and EANM practice guideline for tele-nuclear medicine2.0*. J Nucl Med Tech 2014; 42:15-9.6. The DICOM standard. Digital imaging and communications inmedicine web site. http://medical.nema.org/standard.html.Accessed October 10, 20137. Silva E, Breslau J, Barr RM, Liebscher LA, Bohl M, Hoffman T,et al. ACR white paper on teleradiology practice: A report fromthe task force on teleradiology proactive. J Am Coll Radiol2013; 10:575-85.8. Sharma AR. Emergency Nuclear Medicine. Indian J Nucl Med2011; 26:1-2.9. Bajc M, Neilly JB, Miniati B, Schuemichen C, Meignan M,Jonson B. EANM guidelines for ventilation/perfusionscintigraphy part 2. Algorithms and clinical considerations fordiagnosis of pulmonary emboli with V/PSPECT and MDCT.Eur J Nucl Med Mol Imaging 2009; 36:1528-38.10. Bajc M, Jonson B. Ventilation/perfusion SPECT for diagnosisof pulmonary embolism and other diseases. Int J Mol Imaging2011; 2011:682949.11. Fatima N, Zaman M, Sajjad Z, Hashmi I. Pulmonary embolismin pregnancy: A diagnostic dilemma. Ann Nucl Med 2011; 25:603-8.12. Brenner DJ, Hall EJ. Computed tomography-an increasingsource of radiation exposure. N Engl J Med 2007; 357:2277-84.13. Fakhry F, Spronk S, van der Laan L, Wever JJ, Teijink JA,Hoffmann WH, et al. Endovascular revascularization andsupervised exercise for peripheral artery disease andintermittent claudication: A randomized clinical trial. JAMA2015; 314:1936-44.14. Nuclear cardiology: Its role in cost effective care. InternationalAtomic Energy Agency Vienna, 2012. IAEA human healthseries N0.18.15. Allen TW, Tulchinsky M. Nuclear medicine tests for acutegastrointestinal conditions. Semin Nucl Med 2013; 43:88-101.16. Hartman MS, Leyendecker JR, Friedman B, Fulgham PF,Heller MT, Hosseinzadeh K. Acute onset of scrotal pain-withouttrauma, without antecedent mass. ACR appropriateness criteria®.17. Uliel L, Mellnick VM, Menias CO, Holz AL, McConathy J.Nuclear medicine in the acute clinical setting: Indications,imaging findings, and potential pitfalls. Radio Graphics 2013;33:375-96.18. Zaman MU, Hussain R, Sajjad Z, Naqvi M, Khan K, Khan G.Declaration of brain death: A diagnostic dilemma: Nuclearmedicine perspective. PJR 2008; 18:87-91.Nuclear medicine imaging in emergency room and priority clinical decision makingJournal of the College of Physicians and Surgeons Pakistan 2017, Vol. 27 (4): 197-199 199

Nuclear Medicine Imaging in Emergency Room and Priority Clinical Decision Making

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Nuclear Medicine Imaging in Emergency Room and Priority Clinical Decision Making

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