111In-Oxine-WBC SPECT/CT of Lumbosacral Facet Joint Septic Arthritis.

Spinal facet joint septic arthritis is a rare pathology associated with pyogenic organisms. It may present in older adults with back pain, fever, and positive bacterial blood cultures. However, clinical presentation may be equivocal, and diagnosis relies on anatomic imaging for differentiation from other pathologies. Magnetic resonance is considered the imaging modality of choice and has been found superior to CT; however, it is unable to differentiate facet joint septic arthritis from other inflammatory arthropathies. We present a case of lumbosacral facet joint septic arthritis as seen on In-oxine-WBC scintigraphy and SPECT/CT.

Brain perfusion single-photon emission computerized tomography/computerized tomography: Stroke-like manifestations of COVID-19 with transient antiphospholipid elevation.

COVID-19 is a viral respiratory disease associated with neurologic complications such as encephalitis or stroke in a minority of patients. The wide variety of neurologic manifestations with often unclear etiology may confound diagnosis and management. We present a young man admitted following an 8-day onset of self-resolving episodes of left hemiplegia and hemifacial droop. Diagnostic work up for seizures and stroke was largely negative. "Intra-ictal" ECD-single-photon emission computerized tomography/computerized tomography was consistent with right middle cerebral artery ischemia. Subsequent diagnostic work up revealed positive COVID-19 screening and newly-elevated antiphospholipid antibodies. Antiepileptic medications were discontinued, and the patient was successfully treated as an outpatient with corticosteroids leading to resolution of symptoms.

False-Positive Ventilation-Perfusion Studies Due to Nonembolic Pulmonary Artery Compromise.

Ventilation/perfusion (V/Q) scans are highly sensitive in detecting clinically significant pulmonary embolisms; however, V/Q mismatches are not specific to pulmonary embolism alone, and other etiologies can cause false-positive results. We present 3 cases where the pulmonary vasculature was compromised, from either intraluminal narrowing or external compression, with resultant mismatches. This raises the importance of interpreting V/Q scan results in conjunction with a thorough medical/surgical history and careful analysis of the chest radiograph.

Retroperitoneal hemangioma demonstrated on blood pool scan.

Retroperitoneal hemangioma is a rare but clinically significant condition that can be challenging to diagnose and characterize on anatomical imaging alone. We present a case of an 80-year-old woman with diabetes and hypertension, who was found to have an abdominal mass diagnosed first on CT abdomen and pelvis in March 2011 and demonstrated to be stable on subsequent MRI study performed 16 months later in July 2012. The mass was later confirmed to be a hemangioma on a 99mTc-red cell study.

Bone densitometry.

Conventional radiographic methods allow physicians to visualize bone structure. However, they do not offer information on the bone mineral density (BMD), which can facilitate early diagnosis and treatment of osteoporosis. Bone densitometry, by contrast, helps to detect bone mineral loss at an early stage because it provides accurate quantitative measurement of BMD. With an emphasis on quantification, shorter scanning time and precision, scientists have been developing BMD measurement devices that use absorption technique. They first developed single-energy absorptiometry (single-photon absorptiometry) by using I-125, which could measure BMD of peripheral bones. Single-photon absorptiometry was replaced by dual-energy absorptiometry (dual photon absorptiometry [DPA]) that used gadolinium-153. DPA had greater accuracy in measuring the BMD of central skeletal bones. Single-energy x-ray absorptiometry was also developed but it had limitations in measuring central skeletal BMD. In the mid-1980s, dual-energy x-ray absorptiometry (DXA) was introduced and widely accepted for the early detection, treatment, and follow-up study of osteoporosis. There are several reasons for the popularity. DXA can measure BMD of posteroanterior spine and hip in a much shorter time than DPA while being capable of measuring BMD of peripheral bones. Other advantages include very low radiation doses to the patients, high image resolution, precision, and stable calibration of the instruments. In recent years, DXA has also been applied to lateral spine for the density of trabecular bone, to the whole body for the measurement of total body bone density and for the body composition, and to the spine for the vertebral fracture assessment. Still, posteroanterior spine and hip scans remain the most common applications of DXA because data on the normal range of BMD of the skeletal sites for different age, sex, and ethnic groups are compiled and made available with the devices, which gives the physician the advantage of an immediate diagnosis.