Schmorl's Node May Cause an Increased FDG Activity

Increased 18F-FAPI uptake in bones and joints of lung cancer patients: characteristics and distributions

OBJECTIVE

This study investigated the distribution and characteristics of various bone and joint lesions on 18F-FAPI PET/CT in lung cancer patients.

METHODS

Seventy-four lung cancer patients who underwent 18F-FAPI PET/CT were reviewed. Bone and joint lesions with elevated 18F-FAPI uptake were recorded and analyzed. The distribution and maximum uptake value (SUVmax) of different benign lesions or bone metastases were presented. In addition, the SUVmax of bone metastases on 18F-FDG and 18F-FAPI-04 PET/CT were also compared.

RESULTS

In 53 patients, a total of 262 lesions presented 18F-FAPI accumulation. Bone metastases were mainly in vertebrae, pelvis, and ribs, while benign lesions were in vertebral margins, alveolar bone, and shoulder joints. The SUVmax of bone metastases was significantly higher than that of benign lesions ([Formula: see text] vs. [Formula: see text], [Formula: see text]), with NSCLC cases having higher SUVmax values than SCLC cases ([Formula: see text] vs. [Formula: see text], [Formula: see text]). Among benign lesions, arthritis and periodontitis demonstrated higher SUVmax than degenerative lesions (arthritis: [Formula: see text]; periodontitis: [Formula: see text]; degenerative diseases: [Formula: see text]; [Formula: see text] and [Formula: see text], respectively). The SUVmax of bone metastases was comparable between 18F-FDG and 18F-FAPI PET/CT. However, 18F-FAPI PET/CT was found to be superior in identifying cranial metastases compared to 18F-FDG PET/CT (TBRmet/brain: [Formula: see text] vs. [Formula: see text], [Formula: see text]).

CONCLUSION

This study demonstrated that 18F-FAPI PET/CT is a valuable imaging modality for detecting bone and joint lesions in lung cancer patients. The SUVmax of malignant lesions was higher than that of benign lesions, but cannot accurately distinguish benign and malignant lesions. The uptake of FAPI differs among lesions with different pathological types.

Schmorl Node Can Cause Increased 68Ga-FAPI Activity on PET/CT

ABSTRACT

68Ga-FAPI is a newly developed tumor imaging agent with promising clinical applications. However, benign lesions may also show increased FAPI activity. We accidentally discovered that Schmorl node expressed FAPI activity in a patient with sweat gland cancer. Thus, greater awareness is needed that Schmorl nodes are a potential reason for false-positive uptake on 68Ga-FAPI PET/CT.

Differentiation between spinal subchondral bone metastasis with focal pathologic endplate fracture and oedematous Schmorl's node

INTRODUCTION

We aimed to identify imaging-based findings that can differentiate between spinal subchondral bone metastasis with focal pathologic endplate fracture and oedematous Schmorl's nodes that have been histopathologically confirmed.

METHODS

Between March 2010 and April 2016, 11 patients who had undergone spinal magnetic resonance (MR) imaging or computed tomography (CT) with final radiologic reports that included 'subchondral bone metastasis with focal pathologic endplate fracture' or 'edematous Schmorl's node' and had also undergone percutaneous imaging-guided spinal biopsies were included. Two radiologists retrospectively evaluated the following imaging features in consensus: size, location, presence of sclerotic margin, presence of intralesional or perilesional enhancement and opposite endplate enhancement of the involved disc, presence of disc height loss and presence of metabolic uptake at a corresponding lesion on nuclear medicine imaging.

RESULTS

A total of 11 patients, including six patients with spinal subchondral bone metastasis with focal pathologic endplate fracture and five patients with oedematous Schmorl's nodes, were included in this study (median age, 58 years; range, 50-63 years; six men). Sclerotic margin (P = 0.002) and enhancement on the opposite endplate of the involved disc (P = 0.047) were significantly different between oedematous Schmorl's node and subchondral bone metastasis with focal pathologic endplate fracture.

CONCLUSION

Sclerotic margin and enhancement on the opposite endplate of the involved disc suggest oedematous Schmorl's node rather than subchondral bone metastasis with focal pathologic endplate fracture. Decreased disc height is likely to be an oedematous Schmorl's node rather than subchondral bone metastasis with focal pathologic endplate fracture.

Evolution of a Schmorl's Node and a Degenerative Osteophyte on Sequential 68Ga-DOTATATE PET/CT Scans: Potential Pitfalls in Neuroendocrine Tumor Imaging

Schmorl's node (SN) arises from the herniation of the nucleus pulposus of the disc through the cartilaginous endplate into the body of the vertebra. Our report describes a patient with carcinoid tumor who underwent a series of Ga-DOTATATE PET/CT scans for follow-up, demonstrating gradually increasing focal vertebral uptake in absence of CT abnormality, suspicious for a metastasis. Both CT and MRI eventually revealed classical findings of a SN. Also observed in the same vertebra is a degenerative osteophyte showing intense Ga-DOTATATE uptake. This interesting case shows 2 benign spinal lesions, which potentially can simulate bone metastasis in patients with neuroendocrine tumors.

Schmorl Nodes Can Cause Increased 68Ga DOTATATE Activity on PET/CT, Mimicking Metastasis in Patients With Neuroendocrine Malignancy

Schmorl node (SN) is the herniation of the nucleus pulposus through the cartilaginous and bony endplate into the adjacent vertebral body. It is documented that SNs produce areas of moderately increased F-FDG uptake. We present a case of a patient with history of neuroendocrine tumor, who underwent Ga DOTATATE PET/CT for follow-up, showing increased focal vertebral uptake suggestive of bone metastasis. CT revealed typical findings of an SN. The presented case indicates that SNs should be considered when encountering focally increased skeletal uptake in Ga DOTATATE PET/CT studies, which can mimic metastasis in patients with history of neuroendocrine tumors.

Uncommon Manifestations of Intervertebral Disk Pathologic Conditions

Beyond the familiar disk herniations with typical clinical features, intervertebral disk pathologic conditions can have a wide spectrum of imaging and clinical manifestations. The goal of this review is to illustrate and discuss unusual manifestations of intervertebral disk pathologic conditions that radiologists may encounter, including disk herniations in unusual locations, those with atypical imaging features, and those with uncommon pathophysiologic findings. Examples of atypical disk herniations presented include dorsal epidural, intradural, symptomatic thoracic (including giant calcified), extreme lateral (retroperitoneal), fluorine 18 fluorodeoxyglucose-avid, acute intravertebral (Schmorl node), and massive lumbar disk herniations. Examples of atypical pathophysiologic conditions covered are discal cysts, fibrocartilaginous emboli to the spinal cord, tiny calcified disks or disk-level spiculated osteophytes causing spinal cerebrospinal fluid (CSF) leak and intracranial hypotension, and pediatric acute calcific discitis. This broad gamut of disease includes a variety of sizes of disk pathologic conditions, from the tiny (eg, the minuscule calcified disks causing high-flow CSF leaks) to the extremely large (eg, giant calcified thoracic intradural disk herniations causing myelopathy). A spectrum of clinical acuity is represented, from hyperacute fibrocartilaginous emboli causing spinal cord infarct, to acute Schmorl nodes, to chronic intradural herniations. The entities included are characterized by a range of clinical courses, from the typically devastating cord infarct caused by fibrocartilaginous emboli, to the usually spontaneously resolving pediatric acute calcific discitis. Several conditions have important differential diagnostic considerations, and others have relatively diagnostic imaging findings. The pathophysiologic findings are well understood for some of these entities and poorly defined for others. Radiologists' knowledge of this broad scope of unusual disk disease is critical for accurate radiologic diagnoses. Online supplemental material is available for this article. (©)RSNA, 2016.

Papillary Thyroid Carcinoma Metastasis to the Lumbar Spine Masquerading as a Schmorl's Node

A Schmorl's node is a common incidental finding encountered during radiologic imaging. Despite the vertebral body being a common site of metastatic disease, a lytic lesion adjacent to an endplate with typical imaging features can often confidently be called a Schmorl's node. This is a case report of a patient with a single well-defined FDG-avid papillary thyroid carcinoma metastasis to the spine that had imaging findings characteristic of a Schmorl's node on CT and MRI. This case is important to consider as it demonstrates that the imaging characteristics of metastatic disease and Schmorl's nodes can overlap.