Prevalence of Incidental Extraspinal Findings on MR Imaging of the Lumbar Spine in Adults: A Systematic Review and Meta-analysis

BACKGROUND

Low back pain is common worldwide. MR imaging may identify extraspinal findings that are not related to the proposed clinical question. The prevalence of extraspinal incidental findings and their clinical significance has not been well-established.

PURPOSE

This review aimed to evaluate the prevalence of extraspinal findings on MR imaging of the lumbar spine in adults and the prevalence of clinically significant incidental findings.

DATA SOURCES

A systematic search of MEDLINE and EMBASE was performed, including studies published before June 14, 2023.

STUDY SELECTION

Studies presenting a prevalence of extraspinal findings in patients 16 years of age or older were included.

DATA ANALYSIS

A random effects meta-analysis was used to generate composite prevalence measures of extraspinal findings, patients with extraspinal findings, and clinically significant findings.

DATA SYNTHESIS

Sixteen studies were included in this meta-analysis, with a total of 19,593 patients and 6,006 extraspinal incidental findings. The overall prevalence of extraspinal findings was 19.9% (95% CI, 11.1%-30.7%). Overall, 26.7% of patients had an extraspinal finding identified (95% CI, 14.8%-40.6%). The most common subgroup of extraspinal findings was genitourinary findings in males (27.1%; 95% CI, 25.6%-28.8%). Data from 8 studies demonstrated the prevalence of clinically significant findings at 5.4% (95% CI, 3.2%-8.1%).

LIMITATIONS

Retrospective populations with small numbers of participants in clinically relevant subgroups may result in heterogeneity and imprecision within composite outcome measures.

CONCLUSIONS

Extraspinal findings are common, detected in more than one-quarter of patients. Five percent of findings are clinically significant and may require further action.

Benign-appearing Incidental Adnexal Cysts at US, CT, and MRI: Putting the ACR, O-RADS, and SRU Guidelines All Together

Adnexal cysts are a common incidental finding at US, CT, and MRI but have historically caused a diagnostic dilemma for determining when to follow up and how to manage them. Characteristic imaging features of simple adnexal cysts include a simple fluid collection with smooth walls and no solid or vascular components. Day-to-day practice guidelines were recently updated to reflect the overwhelming evidence that incidental cystic adnexal masses are almost always benign. Three major consensus articles on adnexal cystic masses were published between 2019 and 2020: the Society of Radiologists in Ultrasound (SRU) consensus update on adnexal cysts, the Ovarian-Adnexal Reporting and Data System (O-RADS) US consensus guideline, and the American College of Radiology (ACR) white paper on the management for incidental adnexal findings at CT and MRI. All three standardize reporting terminology, are based on evidence-based data and institutional practice patterns, and apply to nonpregnant women of average risk for ovarian cancer. While there are small differences in follow-up recommendations based on size thresholds, the goal of each is the same-to limit unnecessary imaging follow-up and, by doing so, save the patient time, money, and anxiety. For the diagnostic radiologist to use these guidelines, it is essential that the entire mass is visualized well. Without adequate visualization, further characterization of the mass may be necessary. To put it all together, the SRU consensus guideline and ACR white paper are easily applied in day-to-day practice for masses that are O-RADS 2 and below. An invited commentary by Patel is available online. The online slide presentation from the RSNA Annual Meeting is available for this article. ^©RSNA, 2022.

Prevalence and clinical potential of extraspinal incidental findings in lumbosacral spine MRI of patients with suspected disc diseases

BACKGROUND Incidental findings could be observed in organs close to the spine while reporting lumbosacral spine magnetic resonance imaging (MRI). This study aimed to report the prevalence and clinical potential of extraspinal incidental findings in lumbosacral MRI of patients with suspected disc diseases. METHODS This single-centered cross-sectional study was carried out on 420 consecutive adult patients who underwent lumbar spine MRI for suspected disc disease from January to July 2019. The MRI was checked for the presence of extraspinal incidental findings, and each finding was categorized according to the body organ and its clinical significance. Each MRI plane that best displayed the findings was recorded, and the association between the findings and patient's age and sex was determined. RESULTS Of 420 samples, 135 cases showed extraspinal findings (32.1%), and 7.6% of the patients displayed suspicious lesions. The urinary tract was the most common system (18.6%) to display both clinically significant (5.0%) and benign findings (13.6%), and the axial MRI section was the plane which showed most of the incidental findings. Incidental findings in any body system were rarely found in the younger patients. Females had significantly higher benign findings than males (p = 0.002). CONCLUSIONS The prevalence of extraspinal findings in lumbosacral spine MRI is high, and some are significant. Most findings are related to the urinary tract and best displayed in the axial plane.

Preparing for the Unexpected: A Review of Incidental Extraspinal Findings on Computed Tomography/Magnetic Resonance Imaging of the Spine

Potentially clinically important incidental/unexpected extraspinal findings occur with sufficient frequency in cross-sectional imaging of the spine to warrant the radiologist's careful consideration, regardless of whether the interpreter is a neuroradiologist, a musculoskeletal radiologist, an emergency radiologist, or a generalist. Awareness of the commonly encountered incidentalomas and the anatomy contained within the field of view of cervical, thoracic, and lumbar spine cross-sectional imaging examinations, respectively, assists radiologists in their efficient and accurate analysis. This article familiarizes radiologists with some of the potential relevant extraspinal findings that may be encountered, and recommends an extraspinal search pattern for each spinal segment.

Incidental extraspinal imaging findings on adult EOS full body radiographs: prevalence and clinical importance

Purpose

The purpose of this study was to review our institutional experience with the EOS machine in order to identify the incidence and clinical significance of incidental extraspinal findings (IESF) in an adult spinal deformity population.

Methods

Our institutional database was queried for all full-length standing radiographs generated by the EOS machine. Dictations were reviewed and the number of incidental extraspinal findings were classified using a previously described system. All findings related to the spine were excluded. A subset of electronic medical records were reviewed to determine further workup for individual findings of suspected clinical significance.

Results

Original database query based on radiology reports returned a total of 1857 EOS studies. Duplicate studies, studies without the entire body, and patients with more than 1 study during the search period were excluded. 503 patient studies (55.5% female, mean age 59-years-old, range 18 to 91-years-old) met inclusion criteria. The overall rate of incidental extraspinal findings in our study was 60.4% (304 findings in 503 patients). Most findings were classified as Minor. The rate of Major and Moderate findings was 4.8%. The final rate of clinically significant incidental extraspinal findings was 0.8% and included 3 presumed metastatic lesions in long bones and 1 pulmonary nodule.

Conclusion

To our knowledge this is the first study that reports the rate of incidental extraspinal findings on full body EOS studies. We report a low rate (0.8%) of clinically significant incidental extraspinal findings which is lower than that of CT or MRI. Further research is warranted in comparing EOS and standard radiography.

Extraspinal findings prevalence and clinical significance in 4250 lumbar spine MRI exams

To assess extraspinal findings (ESFs) prevalence in lumbar spine MRI, including clinically significant findings using a systematic approach, and to determine their reporting rate. Lumbar spine MRI scans were retrospectively reviewed over 18 months by two radiologists. Reading discrepancies were resolved by consensus. ESFs were classified according to the involved system, clinical diagnosis, and clinical significance. The reporting rate was estimated by referring to the original report. There were 1509 ESFs in 1322/4250 patients with a substantial agreement between the two radiologists (kappa = 0.8). Almost half (621/1322) were in the 45–60 age group. Females represented 56.6% (748/1322). 74.2% (1120/1509) of the ESFs involved the urinary system among which 79.6% (892/1120) were renal cysts. Clinically significant findings represented 8.7% (131/1509) among which hydronephrosis represented 23% (30/131). First time detected malignant lesions represented 4.6% (6/131). ESFs reporting rate was 47.3%. 58.8% of the clinically significant ESFs were not reported. ESFs prevalence was 31.1%. The Urinary system was the most commonly involved. Most ESFs were benign warranting no further workup. However, clinically significant ESF were not infrequently detected. More than half of the clinically significant findings were not reported. A systematic review of MRI images is highly recommended to improve patient’s outcome.

Incidental findings in lumbar spine MRI: their prevalence and potential impact on patient management

Background

To document the prevalence of extra spinal findings in lumbar MRI

Results

Among the scanned 400 patients, 90 cases had incidental non-spinal findings, and in 30 out of these 90 patients, the finding was the only reason for their complaint.

Conclusions

Radiologists should give attention to the non-spinal findings in lumbar spine MRI, as the detected pathology could be the source of pain or could potential life-threatening conditions.

Incidentalomas in Spine and Spinal Cord Imaging

Incidentalomas are common in magnetic resonance imaging (MRI) of the spine. These incidental findings (IFs) can be seen involving the spinal cord, nerve root, vertebral body, posterior arch and the extraspinal region. This review article describes the imaging findings, stratifies the IFs similar to the computed tomography (CT) colonography reporting and data system and briefly mentions the current recommendations for further evaluation and management of IFs. Radiologists are the first to detect these lesions, suggest further evaluation and management of IFs. It is therefore mandatory for them to be aware of recommendations in clinical practice in order to avoid increased patient anxiety, excessive healthcare expenditure and inadvertent therapeutic procedures.

Beyond the Spinal Canal

Cross-sectional spinal imaging is common, and extraspinal findings are often incidentally identified during interpretation. Although some of these findings may cause symptoms that mimic a spinal disorder, the majority are entirely asymptomatic and incidental. It is essential that the radiologist not only identify those abnormalities that may have clinical significance but also recognize those that are clinically irrelevant and thereby prevent patients from being subjected to further unnecessary, expensive and potentially harmful interventions. This article focuses on those abnormalities that are commonly encountered and provides practical guidance for follow-up and management based on current recommendations.

Incidental extraspinal findings in the lumbar spine during magnetic resonance imaging of intervertebral discs

Purpose

To calculate the frequencies of incidental extraspinal findings and incidentally detected congenital anomalies or anatomical differences in the lumbar spine on magnetic resonance imaging (MRI) scans of intervertebral discs.

Materials and methods

A total of 379 lumbar spine MRI cases were prospectively investigated in the period spanning from August 2016 to January 2018. Both 1.5 and 0.35 Tesla MRI units (Toshiba and Siemens Medical Systems) were used to examine patients with clinically suspected intervertebral disc abnormalities at three MRI diagnostic centers in Khartoum State, Sudan.

Results

Of the 379(100%) patients, 90(23.7%) patients were presented with incidental findings. Among the incidental findings, 39(10.3%) were renal cysts, 10(2.6%) were retroverted uteri, 5(1.3%) were Nabothian cysts, 4(1.1%) were ovarian cysts, 10(2.6%) were uterine fibroids, 3(0.8%) were endometrial thickening, 11(2.9%) were indicative of hydronephrosis, 4(1.1%) were uncovered prostatic enlargement, 2(0.5%) were atrophic kidney, and 1(0.3%) each was of an ectopic kidney and bladder wall thickening, respectively.

Conclusions

A high percentage of extraspinal pathological findings were detected during MRI lumbar spine scans of intervertebral discs. Thus, it is important to be aware of the high percentage of patients who undergo further evaluation given the presence of unexpected findings, but for whom clinical confirmation of these abnormalities is not obtained.

Lumbar Transforaminal Epidural Steroid Injections: Incidental Extraspinal Findings on Planning Imaging

OBJECTIVE

Planning imaging performed during CT-guided procedures may occasionally contain important incidental findings. The purpose of this study was to identify and characterize by clinical relevance the extraspinal findings detected on planning imaging for CT-guided lumbar transforaminal epidural steroid injections (TFESIs).

MATERIALS AND METHODS

Four radiologists retrospectively evaluated the planning scout views and CT studies for 488 consecutive CT-guided lumbar TFESIs performed in 400 patients over a 1-year period. Incidental extraspinal findings were identified and used to characterize patients by the need for follow-up using the CT Colonography Reporting and Data System (C-RADS), a classification scheme originally developed to characterize incidental findings on CT colonography. Patients with C-RADS E4 findings have potentially important findings that should be communicated to the referring physician; patients with C-RADS E3 findings have findings that are likely unimportant, but workup may be indicated. All previously unknown C-RADS E3 and E4 findings discovered in the course of this research were reported to referring physicians for appropriate patient follow-up.

RESULTS

Ten of 400 (2.5%) patients were classified as C-RADS E4; the most common C-RADS E4 finding was vascular aneurysm or stenosis (4/400, 1.0%). Thirteen of 400 (3.3%) patients were classified as C-RADS E3; the most common C-RADS E3 finding was hepatomegaly (4/400, 1.0%). Of 22 patients with C-RADS E3 and E4 findings unknown to clinicians, the finding for only one (4.5%) was communicated to clinicians at the time of the procedure.

CONCLUSION

Clinically important incidental extraspinal findings were identified in 5.8% of patients on the planning imaging performed for CT-guided lumbar TFESIs. Communication of clinically important findings was poor (4.5%).

Incidental findings on CT for suspected renal colic in emergency department patients: prevalence and types in 5,383 consecutive examinations

PURPOSE

This study aimed to determine the prevalence, importance, and types of incidental findings (IF) in non-enhanced CT scans performed for suspected renal colic, based on ACR white papers and other accepted radiographic recommendations.

METHODS

Retrospective review of 5,383 consecutive finalized reports of nonenhanced CT using renal colic protocol performed on adult patients at 2 emergency departments over a 5.5-year period. IF were defined as those unrelated to symptoms (as opposed to alternate causes of symptoms) and were categorized as "important" if follow-up was recommended based on recently published consensus recommendations. Subsets of reports of those with important IF were blindly re-reviewed to calculate inter-rater variability for presence and categorization of important IF.

RESULTS

Important IF were identified in 12.7% (95% confidence interval [CI]: 11.8%-13.6%) of scans. Prevalence of important IF increased with age: important IF in individuals age >80 years were 4 times more common than for those aged 18-30 years: 28.9% (95% CI: 22.4%-36.4%) versus 6.9% (95% CI: 5.5%-8.6%), respectively, P ≤ .05. Women had a higher prevalence of important IF compared with men: 13.4% (95% CI: 12.2%-14.7%) versus 11.9% (95% CI: 10.7%-13.2%), but the difference was not statically significant (P = .09). There was substantial inter-rater agreement (kappa ≥ 0.69) regarding presence and classification of important IFs using published guidelines.

CONCLUSIONS

Important IF occurred in 12.7% of non-enhanced CT scans performed for suspected renal colic in the emergency department and are more common in older individuals. Prospective studies that use radiographic recommendations to characterize IF and examine the outcome and cost of their workup are encouraged.

Incidental Extraspinal Findings at Lumbar Spine Magnetic Resonance Imaging: A Retrospective Study

STUDY DESIGN

Retrospective study of a consecutive series of patients undergoing lumbar spine magnetic resonance imaging (MRI) for low back pain at a single institution.

OBJECTIVE

To determine the prevalence and nondetection rate of incidental extraspinal findings (IESFs) in adult patients undergoing MRI of the lumbar spine performed for low back pain by using a structured approach.

SUMMARY OF BACKGROUND DATA

Extraspinal findings are depicted on lumbar spine magnetic resonance image. There is limited evidence concerning their prevalence, importance, how often they are missed by interpreting physician, and how to improve their detection.

METHODS

Our study was approved by our institutional review board committee, which waived informed consent because it was retrospective. Lumbar spine magnetic resonance images obtained for low back pain at our institution from January 2011 to December 2013 were assessed by 3 readers for IESFs using a structured approach and their results compared with the archived reports. Repeat lumbar spine MRI and cases with a history of trauma were excluded. A total of 3024 lumbar spine magnetic resonance images were included. IESFs were classified according to the organ involved and to the model adopted by the modified CT Colonography Reporting and Data System (C-RADS). Nondetection rates were determined by comparing the results of our structured approach with the archived MRI reports.

RESULTS

A total of 859 IESFs were found in 671 of 3024 lumbar spine patients undergoing MRI (22%). A total of 623 out of them (73%) were categorized E2 (clinically unimportant finding), 192 (22%) were categorized E3 (likely unimportant finding), and 44 (5%) were categorized E4 (potentially important finding). A total of 347 of 859 findings were not mentioned in the archived reports for a nondetection rate of 40%. The nondetection rate for E4 category findings was 38.6% (17/44).

CONCLUSION

IESFs on lumbar spine MRI are common with a significant nondetection rate of 40% using a nonstructured approach. Specifically, there was a significant nondetection rate of 38.6% for potentially important (E4) findings.

LEVEL OF EVIDENCE

3.

Extraspinal Incidental Findings on Routine MRI of Lumbar Spine: Prevalence and Reporting Rates in 1278 Patients

Objective

The aim of the present study was to determine the prevalence and reporting rate of incidental findings (IF) in adult outpatients undergoing lumbar magnetic resonance imaging (MRI).

Materials and Methods

Re-evaluation of a total of 1278 lumbar MRI images (collected from patients with a mean age of 50.5 years, range 16-91 years) captured between August 2010-August 2011 was done by a neuroradiologist and a musculoskeletal radiologist. IFs were classified according to organ or system (liver, gallbladder, kidney, bladder, uterus, ovary, lymph node, intestine and aorta). The rate of reporting of a range of IF was examined. The outcome of each patient's treatment was evaluated based on review of hospital records and by telephone interviews.

Results

A total of 253 IFs were found in 241 patients (18.8% of 1278). Among these, clinically significant IFs (n = 34) included: 2 renal masses (0.15%), 2 aortic aneurysms (0.15%), 2 cases of hydronephrosis (0.15%), 11 adrenal masses (0.86%), 7 lymphadenopathies (0.55%), 6 cases of endometrial or cervical thickening (0.47%), 1 liver hemangioma (0.08%), 1 pelvic fluid (0.08%) and 2 ovarian dermoid cysts (0.15%). Overall, 28% (71/253) of IFs were included in the clinical reports, while clinically significant findings were reported in 41% (14/34) of cases.

Conclusion

Extraspinal IFs are commonly detected during a routine lumbar MRI, and many of these findings are not clinically significant. However, IFs including clinically important findings are occasionally omitted from formal radiological reports.

Extra-spinal incidental findings at lumbar spine MRI in the general population: a large cohort study

OBJECTIVE

To determine the prevalence of clinically and non-clinically relevant extra-spinal incidental findings (IF) in patients undergoing magnetic resonance imaging (MRI) of the lumbar spine and to evaluate the rate of undetected findings in archived radiological reports.

METHODS

A retrospective search of patients undergoing lumbar spine MRI from January 2006 to December 2010 was conducted. By means of randomisation, we retrospectively reviewed 3,000 lumbar spine MRI examinations. Extra-spinal abnormalities were classified according to a modified CT Colonography Reporting and Data System (C-RADS). We retrospectively compared our structured approach with the archived MRI reports as it regarded the detection of extra-spinal IF to estimate non-detection rates.

RESULTS

By means of the structured approach used, extra-spinal findings were detected in 2,060 (68.6 %) of the 3,000 lumbar spine MRI examinations; 362 (17.6 %) patients had indeterminate or clinically important findings (E3 and E4) requiring clinical correlation or further evaluation. After review of the original archived radiological reports, potentially important C-RADS E3 and E4 extra-spinal IF were respectively reported in 47 of the 265 (17.7 %) and in 8 of 74 (10.8 %) patients.

CONCLUSIONS

Our study shows that incidental extra-spinal findings at conventional lumbar spine MRI are common but underestimated in radiological reports.