NUCS DDX by pengtt

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									NUCS DDX                                                                                                                          EC

Scan                        Dose/Radiopharmaceutical                                Tracer T1/2    Energies         Decay
Bone                        20 mCi Tc-99m-MDP                                       Tc-99m 6 hr    140 keV          IT
Lung                        4 mCi Tc-99m-MAA, 20 mCi Tc-99m-DTPA                    I-123  13.3 hr 159 keV          EC
Heart                       3 mCi Tl-201, 20 mCi Tc-99m-mibi                        I-131  8.1 d   364 keV          beta
RVG                         20 mCi Tc-99m-RBC                                       In-111 2.8 d   172, 247 keV     EC
Thyroid                     300 uCi PO I-123 or 10 mCi IV Tc-99m-O4                 Ga-67 78 hr    93, 185, 300 keV EC
                            4 mCi I-131                                             Co-57 270 d    122, 136 keV     EC
Parathyroid                 20 mCi Tc-99m-mibi                                      Cr-51 28 d     320 keV          EC
Renal                       4 mCi Tc-99m-DTPA or 5 mCi Tc-99m-MAG3                  F-18   109 min 511 keV          positron
Testicular                  10 mCi Tc-99m-O4                                        Xe-133 5.3 d   81 keV           beta
Liver-spleen                3 mCi Tc-99m-sulfur colloid                             Tl-201 73 hr   69-83 keV        EC
Liver (blood pool)          20 mCi Tc-99m-RBC
Hepatobiliary               1 mCi Tc-99m-DISIDA
Brain                       20 mCi Tc-99m-ECD or Tc-99m HMPAO
Infection                   10 mCi Ga-67 citrate or 500 uCi In-111 WBC or 5 mCi Tc-99m-HMPAO WBC (small bowel)
GI bleed                    20 mCi Tc-99m-RBC
Meckel’s                    10 mCi Tc-99m-O4
Gastric emptying            250 uCi PO Tc-99m-sulfur colloid
Lymphoscintigraphy          800 uCi SC Tc-99m-sulfur colloid (4 deep, 4 superficial)
Tumor                       10 mCi FDG-18; 10 mCi Ga-67 citrate; 500 uCi I-131 MIBG;5 mCi In-111-octreotide

QA: Al breakthrough <10 ug/ml; Mo breakthrough <0.15 uCi/1 mCi Tc99m; Mo breakthrough determined by counting eluate in well
counter without and with lead shield; radiochemical purity determined with thin layer chromatography, free Tc04 migrates in saline and
methanol, Tc99m compounds migrate in saline only; daily - extrinsic flood with collimator with Co57 sheet source (10 million counts),
intrinsic flood without collimator with Tc-99m-O4 point source at ceiling; weekly – bar phantom; biweekly – SPECT floods (120 million
counts)
Poor image quality: wrong photopeak, patient too far from collimator, wrong type of collimator, wrong isotope, cracked crystal, cracked
PMT, tracer contamination on crystal
PIOPED criteria: high prob (>80%) - >2 large (>75%) segmental V/Q mismatches or arithmetic equivalent in moderate or large and
moderate defects; intermediate prob (20-79%) – 1 moderate (25-75%) to 2 large segmental V/Q mismatches or arithmetic equivalent, single
matched V/Q defect with clear CXR, triple matched defects; low prob (<20%) – nonsegmental perfusion defects, any perfusion defect with
substantially larger CXR abnormality, matched V/Q defects with normal CXR, any number of small (<25%) perfusion defects with normal
CXR; normal – no perfusion defects
V/Q mismatch: PE, tumor compression of PA, hypoplastic PA, vasculitis, atelectasis (reverse mismatch)
Matched V/Q defects: consolidation, COPD, atelectasis, tumor, bulla, pneumonectomy
Lung scan (other): clumped MAA, stripe sign, fissure sign; R to L shunt – activity in kidneys and brain; central deposition of DTPA –
COPD; liver uptake on perfusion study – SVC obstruction; liver uptake on ventilation study – fatty liver; delayed washin and washout on Xe
study – air trapping; Xe leak – BPF
Cardiac: perfusion defects – reversible is ischemia, fixed is infarct or hibernating; wall motion – normal, akinesis (scarred), hypokinesis
(injured), dyskinesis (paradoxical wall motion, CABG, aneurysm), tardokinesis; RUG – adriamycin stopped if EF<45% or drops 15%
Stress test endpoints: severe angina, hypotension, arrhythmias, AMI, fatigue, dyspnea, target workload achieved
Pharmacologic stress: unable to exercise, use persantine (0.142 mg/kg/min) or adenosine, reverse with theophylline (50-100mg), use
dobutamine if COPD on theophylline; use pharmacologic stress for LBBB (o/w may see reversible septal defect)
Increased lung uptake on thallium: LV failure, pulmonary venous HTN
Viable myocardium: normal, reversible defect, fixed defect with >50% tracer uptake of normal myocardium; hibernating – blood flow and
function chronically reduced; stunned – blood flow normal and function reduced
False negative thallium: submaximal exercise, noncritical stenosis, small ischemic area, medications
False positive thallium: any cardiomyopathy, LBBB, infiltrative cardiac disease, ST attenuation
Paradoxical septal movement: septal ischemia, previous cardiac surgery, LBBB or pacemaker, RV overload
Pyrophosphate uptake: MI, LV aneurysm, cardiomyopathy, myocarditis, pericarditis, amyloid
GB not visualized: acute cholecystitis, prolonged fasting, recent meal, cholecystectomy, GB agenesis
Biliary system not visualized: biliary atresia, long-standing bile duct obstruction
Low hepatic and renal activity: severe liver disease, neonatal hepatitis
Bowel not visualized: choledocholithiasis, ampullary stenosis, CCK given pre-scan
Abnormal tracer collections: bile leak, choledochal cyst, Caroli’s, duodenal diverticulum; rim sign specific for acute cholecystitis
False negative HIDA: duodenal diverticulum simulating GB, accessory cystic duct
False positive HIDA: recent meal, prolonged fasting, liver dysfunction, hyperalimentation
Pharmacologic HIDA: if GB not seen in 60 min, can give morphine 0.04 mg/kg (2-3mg) and scan for additional 30 min, but don’t give if
morphine allergy or CD obstruction; if bowel not seen at 60 min, can give CCK 0.02 ug/kg (1-2ug) and scan additional 30 min, also can
evaluate GB EF (30% in 30 min), can give CCK prior to scan if distended; phenobarbitol 5 mg/kg/day x 5 days prior to scan for biliary
atresia and delayed scan up to 24 hrs
Sulfur colloid: focal liver uptake - FNH, regenerative nodule, Budd-Chiari (hot caudate), SVC or IVC obstruction; renal transplant uptake –
rejection; colloid shift into marrow, spleen, lungs, kidneys – severe liver dysfunction; all hepatic masses cold except for FNH; filtered SC for
sentinel node study – breast, melanoma
Blood pool: hemangioma (2cm); if immediate uptake consider hypervascular met; heat damaged rbc – splenic remnant, splenosis, accessory
spleen
GI bleed scan: sensitivity 0.1 ml/min; uptake conforming to bowel with no change over time – IBD, TcO4 excreted into bowel; uptake
conforming to bowel with progressive accumulation over time -–hemorrhage; uptake not conforming to bowel – aneurysm
RLQ activity on Meckel scan: Meckel’s diverticulum with ectopic gastric mucosa (25%), other duplication cyst with ectopic gastric
mucosa, renal, active bleeding sites, tumor, IBD; prep with pentagastrin and cimetidine
Gastric emptying: 50% in 50 min; delayed – diabetic gastroparesis, obstruction; rapid - postoperative, PUD, ZE syndrome, drugs
Focal renal cold defects: tumor, cyst, abscess, scar, duplex collecting system, trauma, infarct; DMSA – pyelonephritis, scar
Focal hot renal lesions: collecting system, leak, cross-fused ectopic, horseshoe
Dilated ureter or collecting system: reflux (most common), obstructed or nonobstructed ureter (Lasix renogram to distinguish, delayed
parenchymal clearance >20min)
Delayed uptake and excretion (renal failure): prerenal – poor flow and uptake, unilateral, RAS (ascending pattern with captopril, beware
of hypotension), RVT; renal – bilateral, ATN (nl uptake, poor excretion), GN (poor uptake and excretion), CRF; postrenal – obstruction
Nonvisualized kidney: nephrectomy, ectopic kidney, renal artery occlusion, hyperacute rejection in transplant
Renal transplant complications: ATN, cyclosporine toxicity, acute rejection, obstruction, urinoma, lymphocele, hematoma, abscess
Decreased testicular uptake: torsion, orchiectomy
Increased testicular uptake: epididymoorchitis
Ring sign: late torsion, tumor with central necrosis, abscess, trauma
Focal hot bone lesions: tumor; inflammation – osteomyelitis, arthritis; congenital – OI, TORCH; metabolic – marrow hyperplasia, Paget’s,
FD; trauma – fracture (rib fxs linear distribution), stress fx (e.g. Honda sign), avulsion injury, AVN, RSD, THR (negative within 6 mos),
spondylolysis, child abuse; vascular – sickle cell; transient osteoporosis of hip; flare phenomenon – good response to chemotherapy
Focal cold bone lesions: mets most common – myeloma, lymphoma, renal, thyroid, neuroblastoma; primary bone lesions – SBC, ABC, EG;
vascular – infarction, AVN (get pinhole view), radiation; artifact – overlying pacemaker, barium, jewelry, prosthesis
Positive 3-phase bone scan: osteomyelitis, healing fx, tumor, orthopedic implants, AVN, RSD, neuropathic osteoarthropathy; cellulitis –
flow and blood pool positive, delayed negative; shin splints – flow and blood pool negative, delayed positive
Superscan: diffuse high bone uptake, diminished soft tissue and renal activity, high sternal uptake, increased uptake at costochondral
junction; mets (usu focal) – prostate (most common), breast, lung; metabolic – HPT, renal osteodystrophy, osteomalacia, Paget’s (hot and
cold); myelofibrosis (large spleen)
Diffuse periosteal uptake (tramtrack): HPO, child abuse, venous insufficiency, thyroid acropachy
Extraosseous activity on bone scan: soft tissues – cellulitis, renal failure, radiotherapy ports, myositis ossificans, muscle injury,
dermatomyositis, rhabdomyolysis, tumors with calcifications, neuroblastoma in child, sinusitis, SVC obstruction (upper body), IVC
obstruction (lower body), lymphedema (arm + anterior ribs); injection abnormalities – infiltration, scatter, lymph node uptake, intraarterial
injection (glove phenomenon); kidney – dehydration (most common cause), urinary tract obstruction, hypercalcemia, chemotherapy,
radiation, Al contamination; breast – pregnancy, lactation, mastitis, inflammatory breast CA, steroids, radiation; stomach, GI – free TcO4,
HPT, hypercalcemia, bowel infarction, prior MIBI scan; liver – mets, prior sulfur colloid scan, Al contamination; spleen – sickle cell,
thalassemia, breast CA, lymphoma; lung – HPT, lung tumor, pulmonary hemosiderosis, alveolar microlithiasis, metastatic osteosarcoma,
prior lung scan; pleural – malignant pleural effusion, pleural met, mesothelioma, chest wall tumor, fibrothorax; heart – MI, CM, myocarditis,
pericarditis, amyloid; other – brain infarction, urine in socks contamination, skin contamination, vascular calcification, calcified fibroid,
photopenic bowel from barium; hypercalcemia – increased uptake in lung and stomach and kidney; Al contamination – increased uptake in
liver and kidney; excess TcO4 – increased uptake in soft tissues, salivary, thyroid, stomach, choroid plexus, decreased uptake in bone;
bisphosphonates – diffuse decreased uptake in bones; amyloid – diffuse increased uptake in myocardium
Diffuse increased thyroid uptake: Graves, early Hashimoto’s thyroiditis, toxic MNG, functioning adenoma (focal)
Diffuse decreased thyroid uptake: thyroiditis – subacute, postpartum, late Hashimoto’s; meds – thyroid hormone therapy, iodine intake or
contrast, PTU, tapazole; thyroid ablation – surgery, I131; lingual thyroid; unilateral – surgery, replacement by hypofunctioning tumor,
suppression by hot nodule, hemiagenesis
Heterogeneous thyroid uptake: MNG, multiple autonomous nodules, Hashimoto’s, CA
Cold nodule: adenoma/colloid cyst (85%), CA (10%), focal thyroiditis, hemorrhage, lymph node, abscess, parathyroid adenoma
I-131 therapy: Graves 10-15 mCi, Plummer’s 30 mCi, residual tissue 30-100 mCi, mets 100-200 mCi
Positive parathyroid scan: parathyroid adenoma, hyperplasia, thyroid adenoma, lymph node, CA
Gallium positive scan: sarcoid (lambda and panda sign), PCP, lymphoma (thallium better for low-grade), osteomyelitis (better than wbc
study for discitis/osteomyelitis), amyloid, parotid, lacrimal; KS is gallium(-)/thallium(+); increased lung uptake – sarcoid, PCP, TB, MAI,
CMV, lymphoma, chemotherapy (bleomycin), lipiodol; increased parotid and lacrimal uptake – sarcoid, Sjogren’s, radiation
Diffuse decreased gallium activity: hemochromatosis, iron overload, post-chemotherapy
WBC scan: all infections in abdomen, osteomyelitis, vascular graft infection
Neuroendocrine tumors: MIBG (esp pheochromocytoma, give Lugol’s to protect thyroid), octreotide (hot spleen and kidneys)
PET indications: SPN, NSCLC, melanoma, lymphoma, colorectal, residual/recurrent brain tumor vs radiation necrosis
PET of SPN: false negative – small nodule <1cm, BAC, carcinoid; false positive – benign tumor, inflammation, infection
Brain death: no flow to cerebral cortex, can get hot nose sign
Focal brain cold defect: infarct, neoplasm, hemorrhage, crossed cerebellar diaschisis (contralateral cerebellum no uptake after stroke),
interictal siezure focus; diagnostic patterns – Alzheimer’s (temporal, parietal), Pick’s (frontal, temporal), multiinfarct dementia
Cisternogram: 500 uCi In-111 DTPAintrathecal; evaluate for NPH (activity in lateral ventricles), CSF leak (check nasal pledgets), CSF
shunt patency

								
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