Radiographic identification of challenging gastrointestinal tract foreign bodies: a descriptive study of how appearance varies in air versus water to aid interpretation

OBJECTIVE

To provide veterinarians with updated radiographic descriptions of select radiolucent foreign material in a simulated gastrointestinal environment.

SAMPLE

368 veterinarian respondents from the US.

METHODS

An online survey was administered between June 18, 2023, and July 2, 2023, through a private veterinarian-based social media group. Representative commonly ingested foreign bodies were radiographed surrounded by air and water to simulate being within the gastrointestinal tract. Two examiners evaluated and qualified the opacity of the objects for each environment.

RESULTS

The private social media group had a total of 3,900 members including veterinarians from all disciplines. A total of 362 small animal veterinarians (9.3% of the group) responded to the study reporting a total of 123 foreign objects that were not causing mechanical obstruction at the time of initial presentation. Sixty-eight foreign bodies were reported greater than or equal to 5 times and grouped as balls (n = 4), food (9), fabric (14), wood (3), soft plastic (14), hard plastic (18), or other (6). Most (98.5% [67/68]) objects were easily identifiable in air. In water, 23.5% (16/68) of the objects were obscured, and 39.7% (27/68) had inversion of the major opacity when compared to the opacity in air.

CLINICAL RELEVANCE

The opacity of some ingested radiolucent material can invert relative to air or fluid, which may reflect substantial differences in detection following repositioning. When known dietary indiscretion occurs, radiographing a sample of the material in air and water will improve the accuracy of assessment.

Radiopacity Enhancements in Polymeric Implant Biomaterials: A Comprehensive Literature Review

Polymers as biomaterials possess favorable properties, which include corrosion resistance, light weight, biocompatibility, ease of processing, low cost, and an ability to be easily tailored to meet specific applications. However, their inherent low X-ray attenuation, resulting from the low atomic numbers of their constituent elements, i.e., hydrogen (1), carbon (6), nitrogen (7), and oxygen (8), makes them difficult to visualize radiographically. Imparting radiopacity to radiolucent polymeric implants is necessary to enable noninvasive evaluation of implantable medical devices using conventional imaging methods. Numerous studies have undertaken this by blending various polymers with contrast agents consisting of heavy elements. The selection of an appropriate contrast agent is important, primarily to ensure that it does not cause detrimental effects to the relevant mechanical and physical properties of the polymer depending upon the intended application. Furthermore, its biocompatibility with adjacent tissues and its excretion from the body require thorough evaluation. We aimed to summarize the current knowledge on contrast agents incorporated into synthetic polymers in the context of implantable medical devices. While a single review was found that discussed radiopacity in polymeric biomaterials, the publication is outdated and does not address contemporary polymers employed in implant applications. Our review provides an up-to-date overview of contrast agents incorporated into synthetic medical polymers, encompassing both temporary and permanent implants. We expect that our results will significantly inform and guide the strategic selection of contrast agents, considering the specific requirements of implantable polymeric medical devices.

Minimizing the need for coil attenuation correction in integrated PET/MRI at 1.5 T using low-density MR-linac receive arrays

The simultaneous use of positron emission tomography (PET) and magnetic resonance imaging (MRI) requires attenuation correction (AC) of photon-attenuating objects, such as MRI receive arrays. However, AC of flexible, on-body arrays is complex and therefore often omitted. This can lead to significant, spatially varying PET signal losses when conventional MRI receive arrays are used. Only few dedicated, photon transparent PET/MRI arrays exist, none of which are compatible with our new, wide-bore 1.5 T PET/MRI system dedicated to radiotherapy planning. In this work, we investigated the use of 1.5 T MR-linac (MRL) receive arrays for PET/MRI, as these were designed to have a low photon attenuation for accurate dose delivery and can be connected to the new 1.5 T PET/MRI scanner. Three arrays were assessed: an 8-channel clinically-used MRL array, a 32-channel prototype MRL array, and a conventional MRI receive array. We experimentally determined, simulated, and compared the impact of these arrays on the PET sensitivity and image reconstructions. Furthermore, MRI performance was compared. Overall coil-induced PET sensitivity losses were reduced from 8.5% (conventional) to 1.7% (clinical MRL) and 0.7% (prototype MRL). Phantom measurements showed local signal errors of up to 32.7% (conventional) versus 3.6% (clinical MRL) and 3.5% (prototype MRL). Simulations with data of eight cancer patients showed average signal losses were reduced from 14.3% (conventional) to 1.2% (clinical MRL) and 1.0% (prototype MRL). MRI data showed that the signal-to-noise ratio of the MRL arrays was slightly lower at depth (110 versus 135). The parallel imaging performance of the conventional and prototype MRL arrays was similar, while the clinical MRL array's performance was lower. In conclusion, MRL arrays reducein-vivoPET signal losses >10×, which decreases, or eliminates, the need for coil AC on a new 1.5 T PET/MRI system. The prototype MRL array allows flexible coil positioning without compromising PET or MRI performance. One limitation of MRL arrays is their limited radiolucent PET window (field of view) in the craniocaudal direction.

Subtle Crucial X-Ray Findings in Pediatric Foreign Body Aspiration

Foreign body aspiration (FBA), with potentially life-threatening outcomes, is not unusual in the pediatric population. We report two cases of lobar bronchial radiolucent foreign bodies. Chest X-ray (CXR) showed a slight but significant finding of lobar emphysema without a significant mediastinal shift. This is possibly a key to suspecting foreign bodies. In the clinical field, a stepwise approach to detecting foreign bodies is commonly performed, from less invasive options such as CXR to computed tomography (CT). In this context, clinicians should scrupulously check CXRs when pediatric patients complain of respiratory symptoms, especially with potential FBA history.

Biomechanical Study of a Novel, Expandable, Non-Metallic and Radiolucent CF/PEEK Vertebral Body Replacement (VBR)

Vertebral body replacement is well-established to stabilize vertebral injuries due to trauma or cancer. Spinal implants are mainly manufactured by metallic alloys; which leads to artifacts in radiological diagnostics; as well as in radiotherapy. The purpose of this study was to evaluate the biomechanical data of a novel carbon fiber reinforced polyetheretherketone (CF/PEEK) vertebral body replacement (VBR). Six thoracolumbar specimens were tested in a six degrees of freedom spine tester. In all tested specimens CF/PEEK pedicle screws were used. Two different rods (CF/PEEK versus titanium) with/without cross connectors and two different VBRs (CF/PEEK prototype versus titanium) were tested. In lateral bending and flexion/extension; range of motion (ROM) was significantly reduced in all instrumented states. In axial rotation; the CF/PEEK combination (rods and VBR) resulted in the highest ROM; whereas titanium rods with titanium VBR resulted in the lowest ROM. Two cross connectors reduced ROM in axial rotation for all instrumentations independently of VBR or rod material. All instrumented states in all planes of motion showed a significantly reduced ROM. No significant differences were detected between the VBR materials in all planes of motion. Less rigid CF/PEEK rods in combination with the CF/PEEK VBR without cross connectors showed the smallest reduction in ROM. Independently of VBR and rod material; two cross connectors significantly reduced ROM in axial rotation. Compared to titanium rods; the use of CF/PEEK rods results in higher ROM. The stiffness of rod material has more influence on the ROM than the stiffness of VBR material.

Oral dissolution therapy for renal radiolucent stones, outcome, and factors affecting response: A prospective study

Background:

Urolithiasis is a widespread problem, that affects up to 10% of population. Uric acid stones come second to calcium stones in prevalence (around 10% of urolithiasis). Potassium citrate is currently the treatment of choice for urine alkalization with minimal side effects and high tolerability.

Aims and Objectives:

This study is trying to present the outcome of oral dissolution therapy (ODT) for treating radiolucent renal stones and evaluating factors affecting its success in a prospective manner.

Materials and Methods:

Between 2015 and 2018, 147 patients with solitary radiolucent renal stones were offered ODT using potassium sodium hydrogen citrate (K citrate). The study included patients diagnosed by noncontrast computed tomography (NCCT) with stone size of 5–30 mm in the longest dimension and attenuation less than 600 Hounsfield units (HU). Patient compliance, blood pressure, creatinine level, K level, and tolerance to side effects were followed up at days 3, 7, and 15 and then monthly for 3 months. Follow-up renal ultrasound at 6-week intervals and a final NCCT at the end of treatment. Successful dissolution was defined as complete stone dissolution or residual that measures up to 2 mm in maximum length. Data were collected, tabulated, and analyzed using Stata 12.0 software (Stata Corporation, College Station, TX, USA).

Results:

One hundred and thirty-nine patients were included in the analyses. The age was 45.1 ± 10.5 years. DJ stent was used in 47 (33.8%) patients. Overall response rate was 64.8%. The stone location within the kidney (pelvic or calyceal) showed no difference between responders and non-responders. Stone longest diameter was smaller in responders (17 ± 5.7 mm) versus 19.2 ± 6.1 mm in nonresponders (P value = 0.039). The mean stone attenuation value (HU) was also lower in responders (347.4 ± 68.5 HU) versus (428.9 ± 84.0 HU) in nonresponders with P < 0.001. DJ insertions seemed to have marginal effect on stone dissolution on univariate analysis but found insignificant in multivariate analysis.

Conclusion:

ODT is safe and effective in the treatment of radiolucent renal stones. The efficacy was affected by stone density and stone size with more tendencies to failure with bigger stones and denser stones. Double J stent insertion may facilitate dissolution rate. There was no effect of the baseline urinarypH, hyperuricemia, or stone location on the dissolution rate of the stones.

Ureteral Obstruction Due to Radiolucent Atazanavir Ureteral Stones

Background: Protease inhibitors (PIs) are a well-documented cause of nephrolithiasis. Although medications such as indinavir are known to increase risk of stone formation, the association of newer HIV medications is not as well studied. In this study, we report a case of a patient who developed atazanavir stones.

Case Presentation: A 74-year-old man with HIV on antiretroviral therapy—including atazanavir, a PI—presented with right flank pain. He previously had passed two ureteral stones that were not analyzed. A CT scan showed mild right hydronephrosis without evidence of nephrolithiasis or ureteral obstruction. The patient was presumed to have passed a stone and was discharged home. He returned one day later with persistent flank pain and acute kidney injury that did not improve with intravenous fluid hydration. A right ureteral stent was placed that relieved his symptoms. Subsequent ureteroscopy demonstrated bilateral ureteral stones that were basket extracted. Stone composition was 100% atazanavir. Since being switched off of this medication, the patient has not had any further episodes of renal colic and his renal function has improved to below his baseline level on presentation.

Conclusion: Patients treated with the PI atazanavir are at risk for developing nephrolithiasis and obstructive uropathy. Because these stones can be radiolucent on CT scan, a high level of suspicion is required to accurately diagnose ureteral obstruction in these patients. Alternative effective HIV treatment regimens can to be utilized when clinically indicated.

Radiolucent Skull Clamps for Intra-Operative Imaging: A Technical Note

Conventionally, surgery and procedural-based radiology are performed on different premises. With advances in imaging technology, the operating room is rapidly being transformed into an intraoperative imaging suite. Diagnostic imaging in conjunction with surgery has great utility and by all accounts has great future potential. During the last decade, cone beam computed tomography (CT) scanners have been introduced and have made intraoperative imaging more feasible because these scanners can be made less bulky. The current usefulness of intraoperative magnetic resonance imaging (MRI) or CT for neurosurgery, however, is impaired by the lack of completely radiolucent skull clamps, causing image artifacts. Metal artifacts are particularly problematic, given that they lead to a considerably higher image quality degradation factor for cone beam CT scanners than for conventional CT scanners. Here, we describe our experience with near-radiolucent skull clamps and their associated problems and discuss future improvements to facilitate high-quality image guidance in the field of neurosurgery.

Effect of Clothing on Measurement of Bone Mineral Density

It is unknown whether allowing patients to have BMD (bone mineral density) studies acquired while wearing radiolucent clothing adlib contributes appreciably to the measurement error seen. To examine this question, a spine phantom was scanned 30 times without any clothing, while draped with a gown, and while draped with heavy winter clothing. The effect on mean BMD and on SD (standard deviation) was assessed. The effect of clothing on mean or SD of the area was not significant. The effect of clothing on mean and SD for BMD was small but significant and was around 1.6% for the mean. However, the effect on BMD precision was much more clinically important. Without clothing the spine phantom had an least significant change of 0.0077 gm/cm(2), while when introducing variability of clothing the least significant change rose as high as 0.0305 gm/cm(2). We conclude that, adding clothing to the spine phantom had a small but statistically significant effect on the mean BMD and on variance of the measurement. It is unlikely that the effect on mean BMD has any clinical significance, but the effect on the reproducibility (precision) of the result is likely clinically significant.

Ultrasound in differential diagnosis of periapical radiolucencies: A radiohistopathological study

OBJECTIVES

To evaluate the efficacy of ultrasound in differential diagnosis of periapical radiolucencies.

MATERIALS AND METHODS

Ten patients aged between 19 years and 40 years with periapical lesions associated with anterior maxillary or mandibular teeth were selected and consented for the study. Pre-operative periapical radiographs were obtained. Measurements and provisional diagnoses of the apical areas were made by two specialist observers on two separate occasions. Preoperative ultrasound examinations with Doppler flowmetry were then performed and the images assessed by two specialist observers for the size, contents, vascular supply and a provisional diagnosis made as to whether the lesion was a cyst or granuloma. Endodontic surgery was performed including curettage of the apical tissues to enable histopathological investigation, which provided the gold standard diagnosis. All measurements and findings were compared and statistically analyzed.

RESULTS

Total 10 lesions were identified in 10 patients. On periapical radiographs, lesions were readily identified but observers were unable to differentiate granuloma from cyst using either modality. Where sufficient buccal cortical bone had been resorbed, ultrasound imaging was simple but underestimated the size of the lesions compared with periapical radiographs. In all cases, the ultrasound diagnosis agreed with the histopathological gold standard.

CONCLUSION

Ultrasonography (USG) can provide accurate information about the nature of intraosseous lesions of the jaws before any surgical procedure. It is proposed that USG with Doppler flowmetry can provide an additional diagnostic tool without invasive surgery, where treatment option is nonsurgical.

Pulsatile lavage irrigator tip, a rare radiolucent retained foreign body in the pelvis: a case report

Retained foreign bodies after surgery have the potential to cause serious medical complications for patients and bring fourth serious medico-legal consequences for surgeons and hospitals. Standard operating room protocols have been adopted to reduce the occurrence of the most common retained foreign bodies. Despite these precautions, radiolucent objects and uncounted components/pieces of instruments are at risk to be retained in the surgical wound. We report the unusual case of a retained plastic pulsatile lavage irrigator tip in the surgical wound during acetabulum fracture fixation, which was subsequently identified on routine postoperative computed tomography. Revision surgery was required in order to remove the retained object, and the patient had no further complications.