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TB OR NOT TB? Samantha Epstein Harvard Medical School, MSIII Gillian Lieberman, MD 2 PATIENT PRESENTATION Patient X is an otherwise healthy 36 year old male, originally from Tanzania, who presented to his PCP with: • 3 months of daily HA More recently: • • Nausea/Vomiting Blurry Vision 3 PATIENT PRESENTATION On further questioning, he tells you: • Lost 20-30 pounds over the last 3 months • Drenching night sweats for the past 3 months • Mid-Lower back pain for 6 months 4 PATIENT PRESENTATION PPD was placed… Came back positive at 26 mm 5 PATIENT PRESENTATION PPD was placed… Came back positive at 26 mm HOWEVER… • Received BCG vaccine as a kid in Tanzania • Cleared for TB at immigration • No exposures to TB, no sick contacts, only travel in >15 yrs was to Maine and NYC • Recent HIV test was negative, never incarcerated, no IVDU • No cough, hemoptysis, SOB 6 The patient was admitted to the hospital for further workup… 7 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 8 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 9 MRI: Brief Review What is MRI? • MRI magnet creates a strong magnetic field • Protons within tissue align to magnetic field => equilibrium • Radiofrequency pulses applied = push out of equilibrium • Measure signal emitted as return back to alignment at different points in time 10 MRI: Brief Review What is MRI? • MRI magnet creates a strong magnetic field • Protons within tissue align to magnetic field => equilibrium • Radiofrequency pulses applied = push out of equilibrium • Measure signal emitted as return back to alignment at different points in time Why MRI in this case? • Excellent Soft Tissue Contrast • Pulse sequences utilized to differentiate between cerebral tissues • Relevant Indications: Mass lesions, tumors, infection, inflammation 11 MRI: Indications ACR Appropriateness Criteria 12 MRI: T1 vs T2 T1 Weighted Images SHORT TE AND TR LONG TE AND TR T1 = longitudinal relaxation, time needed to regain longitudinal relaxation after rf pulse T2 = transverse relaxation, decay, rotation as it relaxes after rf pulse Image Acquisition Fat Fluid Fluid Signal Intensity Signal Intensity Image Acquisition T2 Weighted Images Long Decay Fat Short Decay TR TE 13 MRI: T1 vs T2 T1 Weighted Images Black (No H): Air, Calcium, Bone Dark: CSF, edema Grey: White and grey matter Bright: Fat, Gd contrast Companion Patient 1: Normal MRI- T1 vs T2 Edward G. Miner Libarary T2 Weighted Images Black (No H): Air, Calcium, Bone Dark: Gray and White matter Bright: CSF, Edema, Blood 14 MRI: T1 vs T2 T1 Weighted Images FLUID is DARK FAT is BRIGHT Companion Patient 1: Normal MRI- T1 vs T2 Edward G. Miner Library T2 Weighted Images FLUID is BRIGHT FAT is DARK 15 MRI: T1 vs T2 T1 Weighted Images T2 Weighted Images FLUID is DARK FAT is BRIGHT FLUID is BRIGHT FAT is DARK T1 C+: Good for recognition of BBB disruption, vascular changes T2 C+: Good for anatomy And brain lesions, but can’t differentiate lesion from CSF Companion Patient 1: Normal MRI- T1 vs T2 Edward G. Miner Library 16 MRI: FLAIR FLAIR: Fluid Attenuated Inversion Recovery Essentially the same as T2, but with signal from CSF suppressed T2 FLAIR Companion Patient 2: Normal MRI- T2 vs FLAIR Edward G. Miner Library 17 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 18 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 19 Results: T1 Our patient: T1 Axial (Pre-Contrast) MRI Head, Axial, T1 C- Our patient: T1 Axial (Post-Contrast) MRI Head, Axial, T1 C+ PACS, BIDMC 20 Results: T1 Our patient: T1 Axial (Pre-Contrast) Our patient: T1 Axial (Post-Contrast) There is a ring enhancing lesion in the right frontal lobe, clearly visualized on T1 after contrast administration Lesion not visualized in the affected area on T1 without contrast MRI Head, Axial, T1 C- MRI Head, Axial, T1 C+ PACS, BIDMC 21 Results: T1 vs T2 Our patient: T1 Axial (Post-Contrast) MRI Head, Axial, T1 C+ Our patient: T2 Axial (Post-Contrast) MRI Head, Axial, T2 C+ PACS, BIDMC 22 Results: T1 vs T2 Our patient: Our patient: T1 Axial (Post-Contrast) T2 Axial (Post-Contrast) Periventricular hyperintense lesion seen in affected right frontal lobe Same ring enhancing lesion seen earlier PACS, BIDMC MRI Head, Axial, T1 C+ CSF IS DARK MRI Head, Axial, T2 C+ CSF IS BRIGHT Our patient: C+ T1 Our patient: C+ T2 Lesion is BRIGHT 23 Our patient: FLAIR Lesion is BRIGHT MRI Head, Axial, T1 C+ CSF IS BRIGHT CSF IS DARK MRI Head, Axial, FLAIR Results: T1, T2, FLAIR MRI Head, Axial, T2C+ PACS, BIDMC 24 Types of Edema VASOGENIC EDEMA: • Results from a breakdown of the BBB, most common • Think: trauma, infection, tumors, inflammation CYTOTOXIC EDEMA: • BBB maintained, second most common • Think: Ischemic infarcts (early), intoxications INTERSTITIAL EDEMA: • Transudative edema resulting from increased pressure • Think: Hydrocephalus OSMOTIC EDEMA: • Edema caused by change in plasma osmolality • Think: Hyponatremia 25 Types of Edema VASOGENIC EDEMA: • Results from a breakdown of the BBB, most common • Think: trauma, infection, tumors, inflammation CYTOTOXIC EDEMA: • BBB maintained, second most common • Think: Ischemic infarcts (early), intoxications INTERSTITIAL EDEMA: • Transudative edema resulting from increased pressure • Think: Hydrocephalus OSMOTIC EDEMA: • Edema caused by change in plasma osmolality • Think: Hyponatremia Findings? Our patient: FLAIR C+ T1 Our patient: C+ T2 26 Our patient: MRI Head, Axial, T1 C+ MRI Head, Axial, FLAIR Results: T1, T2, FLAIR MRI Head, Axial, T2C+ • • Ring-enhancing Lesion Vasogenic Edema PACS, BIDMC Our patient: 27 C+ T1 Our patient: FLAIR MRI Head, Axial, T1 C+ Our patient: C+ T1 MRI Head, Axial, FLAIR Results: Multiple Lesions MRI Head Axial, T1C+ MULTIPLE • Ring-enhancing Lesions • Vasogenic Edema PACS, BIDMC 28 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 29 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 30 TB: CNS Manifestations 1. Intracranial Tuberculoma: Conglomerate granulomatous (caseous) foci within the brain parenchyma C+T1: Ring Enhancing Lesion: Hyperintense ring: Collagenous fibers Hypointense ring: outer inflammatory infiltrates Inner: Caseating necrosis Kyoung, Kim 31 TB: CNS Manifestations 1. Intracranial Tuberculoma: Conglomerate granulomatous (caseous) foci within the brain parenchyma 2. TB Meningitis *Most common CNS manifestation. LP is best to diagnose (high protein, low glucose, lymphocytic pleocytosis, +/- TB on smear). Can see signs of increased pressure on CT. 32 TB: CNS Manifestations 1. Intracranial Tuberculoma: Conglomerate granulomatous (caseous) foci within the brain parenchyma 2. TB Meningitis *Most common CNS manifestation. LP is best to diagnose (high protein, low glucose, lymphocytic pleocytosis, +/- TB on smear). Can see signs of increased pressure on CT. 3. Spinal tuberculous arachnoiditis : Focal inflammatory disease leading to gradual encasement of the spinal cord in gelatinous or fibrous exudate. Dastur, DK. Companion Patient 3: Spinal TB arachnoiditis 33 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 34 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -Differential -MSK Manifestations of TB 3. Image the CHEST -Findings -Expected findings with TB 35 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: 1. Metastasis 2. Infection 3. Demyelinating Disease 36 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: MAGICAL DR Metastasis Abscess Glioblastoma Multiforme Infarction Contusion Atypical organisms Lymphoma Bacterial: Mycobacteria, Nocardia, Actinomyces Demyelination Radiation Fungal: Crypto, Histo, Aspergillus Parasites: Neurocystircerocosis,Toxoplasmosis, Echinococcus, Entamoeba 37 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: Metastasis Abscess Glioblastoma Multiforme Infarction Contusion Atypical organisms Lymphoma Demyelination Radiation Some helpful differentiating features… 38 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: Metastasis Abscess Glioblastoma Multiforme Infarction Contusion Atypical organisms Lymphoma Companion Patient 4: Multiple Metastases Multiple lesions Usually at Greywhite matter junctions Demyelination Radiation MRI Head, Axial, T1/C+ Khosla, Anil 39 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: Metastasis Abscess Glioblastoma Multiforme Infarction Contusion Atypical organisms Lymphoma Demyelination Radiation Companion Patient 5: Abscess MRI Head, Axial, T1/C+ MRI Head, Axial, FLAIR Thin, regular, enhancing rim Extensive edema relative to lesion Gaillard 40 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: Companion Patient 6: GBM Metastasis Abscess Glioblastoma Multiforme Infarction Contusion Atypical organisms Lymphoma Demyelination Radiation Irregular, heterogenuous, solitary lesion Often crosses corpus callosum MRI Head, Axial, T1/C+ Gaillard 41 Ring Enhancing Lesions RING ENHANCING LESION DIFFERENTIAL: Metastasis Abscess Glioblastoma Multiforme Infarction Contusion Atypical organisms Lymphoma Companion Patient 7: MS Paraventricular white matter lesions “Open ring sign” Demyelination Radiation MRI Head, Axial, T1/C+ Gaillard 42 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 43 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 44 ACR Criteria: Back Pain Which imaging modality? ACR Appropriateness Criteria 45 MRI: Indications Which imaging modality? MRI Relevant Indications: High suspicion for infection, malignancy Greater than 12 weeks of symptoms Advantages: More sensitive than plain radiographs and CT, without the radiation exposure Detection of soft tissue defects, neurological impingement Can accentuate edematous areas Better characterizes the lesion itself 46 Results: Sagittal T-Spine Our Patient: T1 Pre-Contrast MRI T-Spine, Sagittal, T1/C- Our Patient: T2 Pre-Contrast MRI T-Spine, Sagittal, T2/C- PACS, BIDMC 47 T-Spine Anatomy Our Patient: T1 Pre-Contrast Our Patient: T2 Pre-Contrast Intervertebral Discs Vertebral Body CSF (dark) CSF (bright) Spinal Cord MRI T-Spine, Sagittal, T1/C- MRI T-Spine, Sagittal, T2/C- PACS, BIDMC 48 Results: Sagittal T-Spine Our Patient: T1 Pre-Contrast MRI T-Spine, Sagittal, T1/C- Our Patient: T1 Post-Contrast MRI T-Spine, Sagittal, T1/C+ PACS, BIDMC 49 Results: Sagittal T-Spine Our Patient: T1 Pre-Contrast T12 MRI T-Spine, Sagittal, T1/C- Our Patient: T1 Post-Contrast Enhancing mass within T12 vertebral body T12 MRI T-Spine, Sagtital, T1/C+ PACS, BIDMC 50 MRI: Axial T-Spine Our Patient: T11 Vertebral Body (Normal) MRI T-Spine, Axial, T2 Image from: Advanced Practice Strategies PACS, BIDMC 51 Axial T-Spine Anatomy Vertebrae Spinal Cord CSF Epidural Fat Ribs Our Patient: T11 Vertebral Body (Normal) MRI T-Spine, Axial, T2 Image from: Advanced Practice Strategies PACS, BIDMC 52 Results: Axial T-Spine Our Patient: T11 Unaffected Vertebral Body MRI T-Spine, Axial, T2 PACS, BIDMC Our Patient: T12 Affected Vertebral Body MRI T-Spine, Axial, T2 53 Results: Axial T-Spine Our Patient: T11 Unaffected Vertebral Body Our Patient: T12 Affected Vertebral Body Lesion in Vertebral Body Epidural Fat MRI T-Spine, Axial, T2 PACS, BIDMC MRI T-Spine, Axial, T2 Mass effect on the Spinal Cord and Thecal Sac Epidural Fat Impingement 54 Results: Axial T-Spine Our Patient: T11 Unaffected Vertebral Body Our Patient: T12 Affected Vertebral Body Epidural Fat Impingement: notice loss of normal epidural fat border Epidural Fat MRI T-Spine, Axial, T2 PACS, BIDMC Mass effect : Note lack of CSF seen on this T2 MRI T-Spine, Axial, T2 55 Results: Axial T-Spine *Remember: NERVE ROOTS EXIT BELOW THE VERTEBRAL BODIES IN THE THORACIC SPINE Our Patient: Normal (T11 – T 12) MRI T-Spine, Axial, T2 Our Patient: Abnormal (T12- L1) MRI T-Spine, Axial, T2 PACS, BIDMC 56 Results: Axial T-Spine *Remember: NERVE ROOTS EXIT BELOW THE VERTEBRAL BODIES IN THE THORACIC SPINE Our Patient: Normal (T11 – T 12) Our Patient: Abnormal (T12- L1) Impingement on the Neuroforamen MRI T-Spine, Axial, T2 MRI T-Spine, Axial, T2 PACS, BIDMC 57 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 58 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 59 TB: Skeletal Manifestations In order of prevalence: Pott’s Disease Arthritis Osteomyelitis (non-vertebral) Epidural Abscess Psoas Abscess 60 TB: Skeletal Manifestations In order of prevalence: Pott’s Disease Our Patient: Pott’s Disease Arthritis Osteomyelitis (non-vertebral) Epidural Abscess Psoas Abscess MRI, T-spine, Sagittal, T2 61 TB: Skeletal Manifestation In order of prevalence: Companion Patient 8: TB Hip Arthritis Pott’s Disease Arthritis Osteomyelitis (non-vertebral) Epidural Abscess Psoas Abscess Hip> ankle> elbow> wrist > shoulder Singh, et.al 62 TB: Skeletal Manifestations In order of prevalence: Pott’s Disease Companion Patient 9: Chest Wall TB- Osteomyelitis Arthritis Osteomyelitis Epidural Abscess Psoas Abscess Ribs, skull, phalanx, pelvis, long bones Grover et.al 63 TB: Skeletal Manifestations In order of prevalence: Pott’s Disease Companion Patient 10: TB Psoas Abscess Arthritis Osteomyelitis (non-vertebral) Epidural Abscess Psoas Abscess CT Abdomen, Axial, C+ Worry about tracking down into groin Golden et.al 64 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 65 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 66 Differential At this point: -HA, n/v Ring enhancing lesions on MRI -Back pain Enhancing mass in T12 vertebral body -Night sweats, weight loss -Positive PPD, with hx of BCG vaccine 67 Differential At this point: -HA, n/v Ring enhancing lesions on MRI -Back pain Enhancing mass in T12 vertebral body -Night sweats, weight loss -Positive PPD, with hx of BCG vaccine Our Narrowed DDX: TB Endocarditis Neoplastic (Lymphoma) Infectious, other 68 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 69 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 70 Results: CHEST What would you start with? Chest XR If positive findings Chest CT 71 Results: CHEST XR Our Patient: Initial CXR AP Right apical nodular opacities Our Patient: Initial CXR Lateral PACS, BIDMC 72 Results: CHEST CT Our patient: Initial Chest CT Right posterior apical cavitary lesion PACS, BIDMC 73 TB: Pulmonary Findings LESIONS: NON-SPECIFIC Undetectable Focal Infiltrates Lobar Infiltrates CAVITATION *rare in primary Caseating Granuloma Abscess Miliary Nodules Jones, et al 74 TB: Pulmonary Findings LESIONS: NON-SPECIFIC Undetectable Focal Infiltrates Lobar Infiltrates CAVITATION *rare in primary Caseating Granuloma Abscess Miliary Nodules LOCATION OF LESIONS: Primary Infection: Anywhere, Middle and Lower Reactivation: Apical and posterior segments of upper lobe or upper segments of lower lobe Jones, et al 75 TB: Pulmonary Findings LESIONS: NON-SPECIFIC LYMPH NODES: Undetectable Ghon Lesion: Calcified parenchymal tuberculoma Ranke: Ghon Lesion + Calcified ipsilateral draining lymph node Focal Infiltrates Lobar Infiltrates CAVITATION *rare in primary Caseating Granuloma Abscess Miliary Nodules Companion Patient 11: Ghon Lesion and Ranke CompleX LOCATION OF LESIONS: Primary Infection: Anywhere, Middle and Lower Reactivation: Apical and posterior segments of upper lobe or upper segments of lower lobe CT chest, Axial, C- CT chest, Axial, C+ Costa, et al 76 Radiologic Evaluation OVERVIEW: 1. Image the BRAIN -MRI Review -Results -CNS Manifestations of TB -Differential 2. Image the SPINE -Results -MSK Manifestations of TB -Differential 3. Image the CHEST -Findings -Expected findings with TB 77 FINAL DIAGNOSIS Needle Our patient: CT – Guided T12 Biopsy CT Abdomen, Axial, C- CT Abdomen, Axial, C- SPUTUM SAMPLE Acid Fast Bacilii - Mycobacterium TB confirmed by NAAT PACS, BIDMC 78 TREATMENT “RIPE” Therapy: Rifampin Isioniazid Pyrazinamide Ethambutol + Moxifloxacin and IV Amikacin For drug resistant TB, common in Tanzania + Dexamethasone 79 TREATMENT Our patient: Initial CXR AP PACS, BIDMC Our patient: CXR 2 weeks s/p therapy 80 Patient X did well on the therapy outlined above. His HA, N/V, and back pain all resolved early after initiation of therapy. His imaging, as seen above, continued to improve accordingly. After a long hospitalization, he was discharged home on antibiotics and a dexamethasone taper. He had outpatient follow up scheduled at TB Clinic and with Infectious Disease. Our patient was found to be HIV negative and appeared otherwise immunocompetent, without any known exposures to TB. The etiology of his reactivation vs primary TB infection thus remains unclear. 81 Acknowledgements: Gillian Lieberman, MD Jennifer Steinkeler, MD Komal Talati, MD 82 References: 1. Van Stavern, Renee. MRI for Neurology. 2009; Available :http://neuro.wustl.edu/files/6413/4461/5738/Week_3_Handout_MRI_for_Neurology.pdf 2. Dastur DK et al. Neurosurgically relevant aspects of pathology and pathogenesis of intracranial and intraspinal tuberculosis. Neurosurgery Review. 6:103. 3. Akeson P, Larsson EM, Kristoffersen DT. Brain metastases--comparison of gadodiamide injection-enhanced MR imaging at standard and high dose, contrast-enhanced CT and non-contrast-enhanced MR imaging. Acta Radiol. May 1995;36(3):300-6 4. Gaillard, et al. Tuberculosis on Radiology. Radiopaedia.org. Available: http://radiopaedia.org/articles/tuberculosis 5. Kyoung, Kim et al. Intracranial Tuberculoma: Comparison of MR with Pathologic Findings. American Journal of Neuroradiology. 1995. 16; 1903-1908 6. Golden, Marjorie et al. Extrapulmonary Tuberculosis: An Overview. American Family Physician. 2005. 1;72(9):1761-1768. 7. Jones, Jeremy et al. Ranke Complex Radiology. 2014. Available: http://radiopaedia.org/images/832237 8. Leonard, John et al. Central Nervous System Tuberculosis. UpToDate. 2013. Available: www.uptodate.com/contents/ central-nervous-system-tuberculosis? 9. McDonald, Malcolm et al. Skeletal Tuberculosis. UpToDate. 2013. Available: www.uptodate.com/skeletal_tuberculosis 10. Edward G. Miner Library. Axial MRI- T1 vs. T2; Axial MRI- T2 vs. FLAIR. University of Rochester Medical School (2013). Available: http://www.urmc.rochester.edu/libraries/courses/neuroslides04/other.cfm 83 References cont… 11. Singh, Arun Pal. Tuberculosis Arthritis-Pathology and Clinical Features. Bone and Spine. Available: http://boneandspine.com/tuberculous-arthritispathology-clinical-features/ 12. Grover, Shabnam Bhandari et al. Chest Wall Tuberculosis- A clinical and Imaging Experience. Indian Journal of Radiology and Imaging. 2011. 21: 1; 28-33. 13. American College of Radiology. ACR Appropriateness Criteria: Low Back Pain. 2011. Available:http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/LowBackPain.pdf 14. American College of Radiology. ACR Appropriateness Criteria: Headache. 2011. Available at: http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/Headache.pdf 15. Khosla, Anil. Brain Metastases Imaging. Medscape. 2013. Available: http://emedicine.medscape.com/article/338239-overview 16. Costa, Joao et al. The Ranke Complex: Incidental Finding on CT. Euro Rad. 2008. Available:http://www.eurorad.org/eurorad/case.php?id=5346 17. Advanced Practice Strategies. Superior view of thoracic vertebra w/ spinal cord and spinal nerves. 2001. Available : http://www.apsweb.com/projectreview/000sp5.asp 18. Gaillard, Frank. Cerebral ring enhancing lesions. Radiopaedia.org. Available: http://radiopaedia.org/articles/cerebral-ring-enhancing-lesions