Wooden Foreign Bodies: Imaging Appearance

Size: px

Start display at page:

Download "Wooden Foreign Bodies: Imaging Appearance"

Jemima Clark
6 years ago
Views:

1 Downloaded from by on 01/23/18 from IP address Copyright RRS. For personal use only; all rights reserved Jeffrey J. Peterson 1 Laura W. ancroft Mark J. Kransdorf Received May 21, 2001; accepted after revision September 17, Presented at the annual meeting of the merican Roentgen Ray Society, Seattle, pril May ll authors: Department of Radiology, Mayo Clinic, 4500 San Pablo Rd., Jacksonville, FL ddress correspondence to M. J. Kransdorf. JR 2002;178: X/02/ merican Roentgen Ray Society Wooden Foreign odies: Imaging ppearance OJECTIVE. The purpose of this study was to identify the characteristic imaging features of wooden foreign bodies. MTERILS ND METHODS. The imaging studies of 12 patients with surgically confirmed wooden foreign bodies were retrospectively reviewed. The study group consisted of seven females and five males, years old (mean age, 36 years). ll patients underwent radiography. Nine patients were evaluated with sonography, eight with MR imaging, three with CT, and one with CT arthrography. Gadolinium-enhanced MR imaging was performed in six patients. Three patients presented with a draining sinus and nine with painful swelling. Only three patients presented with a history of penetrating injury. RESULTS. Lesions were located in the foot (n = 4), hand (n = 3), thigh (n = 2), calf (n = 2), and elbow (n = 1). Radiographs failed to reveal the retained foreign bodies in all patients. With MR imaging, wooden foreign bodies displayed a variable signal intensity that was equal to or less than that of skeletal muscle on both T1- and T2-weighted images. MR imaging showed the surrounding inflammatory response in all patients. CT showed the retained wood as linear cylindric foci of increased attenuation. Wood was highly echogenic and revealed pronounced acoustic shadowing on sonography. rthrography in one patient showed an associated reactive synovitis. CONCLUSION. The imaging appearance of wooden foreign bodies is variable; however, imaging can be quite specific, and when taken in the appropriate clinical setting, the imaging should reliably suggest the diagnosis. Sonography is frequently underused but proved most useful for the evaluation of retained wooden foreign bodies. D espite advances in imaging techniques, the detection of retained wooden foreign bodies remains a difficult and challenging task. Patients often present for evaluation several months or even years after the initial injury, and consequently, clinical evaluation may fail to elicit a history of antecedent skin puncture. When a history of penetrating trauma is suggested, its severity is difficult to estimate clinically. Even when there is a high suspicion of a retained foreign body, localization remains difficult. Foreign body fragments may remain in the wound even after apparent successful extraction by the patient at the time of injury. The initial physical examination may reveal a painful swollen soft-tissue mass or psuedotumor that may simulate malignancy or infection, rather than suggesting a retained foreign body. The detection of wood is especially important because it may serve as an unrecognized nidus for infection. Wood, with its porous consistency and organic nature, is an excellent medium for microorganisms, and the retained wooden foreign matter may result in cellulitis, abscess, or fistula formation [1]. The wooden foreign matter may also result in synovitis if a joint is violated or in osteomyelitis if adjacent osseous structures become involved. Radiography, CT, MR imaging, and sonography have been advocated for the detection of retained foreign bodies. We reviewed our experience with 12 patients who had retained wooden foreign bodies, only three of whom presented with a history of previous penetrating trauma. Materials and Methods We retrospectively reviewed the imaging studies of 12 patients with surgically confirmed retained wooden foreign bodies. The study group was composed of seven female and five male patients, years old (mean age, 36 years). Radiographs were JR:178, March

Downloaded from www.ajronline.org by 37.44.194.233 on 01/23/18 from IP address 37.44.194.233. Copyright RRS. For personal use only; all rights reserved Peterson et al. available for each patient.

MR imaging included spin-echo T1-weighted sequences and either conventional spinecho dual-echo or short tau inversion recovery sequences. Gadolinium-enhanced imaging was available in six patients.

ll CT scans were examined in both soft-tissue and bone windows. Patient presentation was variable. The most common presenting symptoms were pain and swelling, which were observed in 10 patients.

2 Downloaded from by on 01/23/18 from IP address Copyright RRS. For personal use only; all rights reserved Peterson et al. available for each patient. dditional imaging included the following: sonography (n = 9), MR imaging (n = 8), CT (n = 3), and CT arthrography (n = 1). Sonography was performed using high-resolution phased array probes. MR imaging included spin-echo T1-weighted sequences and either conventional spinecho dual-echo or short tau inversion recovery sequences. Gadolinium-enhanced imaging was available in six patients. ll CT scanning was performed in the axial plane with either a 1- or 3-mm slice thickness. Reformatted images were obtained in the sagittal and coronal planes. ll CT scans were examined in both soft-tissue and bone windows. Patient presentation was variable. The most common presenting symptoms were pain and swelling, which were observed in 10 patients. Three patients presented with a draining sinus. Only three patients presented prospectively with a history of penetrating trauma. The foot was involved in four patients, the hand in three, the thigh in two, the calf in two, and the elbow in one. Results Radiography Radiographs failed to reveal the retained foreign bodies in all patients. one erosion was seen in one patient related to the close proximity of the retained wood to the humerus. The erosion was subtle, and although identified prospectively, the adjacent foreign body was not identified (Fig. 1). MR Imaging MR imaging showed the retained foreign bodies to be hypointense to skeletal muscle on both T1- and T2-weighted sequences. Two patients revealed the retained fragment as a signal void (Fig. 2). The surrounding inflammatory response was seen in all patients. The response was hypointense on T1-weighted images and isointense to hyperintense on T2weighted images in relation to surrounding skeletal muscle and fat, respectively (Figs. 2 4). Gadolinium-enhanced imaging in six patients showed enhancement of the surrounding inflammatory response. CT CT depicted the retained wooden foreign body as a linear or cylindric area of high attenuation compared with the surrounding skeletal muscle and fat (Fig. 5). ll foreign bodies were best visualized on images viewed at a Fig. 1. Retained wooden foreign body in 11-year-old boy with 2-year history of elbow pain and swelling., nteroposterior elbow radiograph shows subtle extrinsic erosion (arrow) related to close proximity of retained wooden foreign body., nteroposterior elbow radiograph after performance of arthrogram shows marked reactive synovitis. C, xial CT scan of elbow after performance of arthrogram reveals subtle hyperattenuating structure, which at surgery proved to be retained wooden foreign body (open arrow) with associated extrinsic erosion to posterior cortex of humerus (solid arrow). C 558 JR:178, March 2002

Downloaded from www.ajronline.org by 37.44.194.233 on 01/23/18 from IP address 37.44.194.233. Copyright RRS. For personal use only; all rights reserved Wooden Foreign odies wide (bone) window.

response, was seen in two patients. Sonography Sonography showed the retained wooden foreign bodies as linear echogenic structures with pronounced acoustic shadowing (Figs. 4 and 5).

3 Downloaded from by on 01/23/18 from IP address Copyright RRS. For personal use only; all rights reserved Wooden Foreign odies wide (bone) window. The surrounding inflammatory response seen on MR imaging was difficult to differentiate from surrounding skeletal muscle, although effacement of surrounding fat planes, indicative of an inflammatory response, was seen in two patients. Sonography Sonography showed the retained wooden foreign bodies as linear echogenic structures with pronounced acoustic shadowing (Figs. 4 and 5). In two patients with larger pieces of wood, only the hyperechoic, crescent-shaped leading edge of the wood was seen with acoustic shadowing obscuring the trailing edge. CT rthrography In one case in which the wooden foreign body was suspected to have traversed the elbow joint, athrography revealed an irregular margin of the joint with a thickened, corrugated synovium (Fig. 1). Contrast material was seen about the retained foreign body. Discussion Radiographs are usually unrewarding in the search for retained foreign bodies, as they were in this series. Radiographs have been reported to reveal a wooden foreign body in only 15% of patients [2]. Wooden foreign bodies are usually radiolucent, associated with gas in the matrix. However, the small size of the foreign body often is not sufficient to create an appreciable radiolucency [3]. In one patient in our series, the wooden foreign body came to rest in close proximity to the distal humerus, with subsequent nonspecific extrinsic erosion of the underlying cortex (Fig. 1). When retained foreign bodies penetrate or lie adjacent to bone, osteolytic, osteoblastic, or a combination of changes can occur [4]. Unfortunately, this can often confuse the situation further and suggest another underlying process other than a retained splinter. Xeroradiography has been reported as slightly more sensitive than conventional radiography for the detection of retained wood; however, xeroradiographs show negative results in 80% of patients and are not available in most radiology departments [2]. CT has been shown to be useful in the evaluation for suspected wooden matter. In our series, retained wooden foreign bodies were more subtle when using the standard window and level setting. When the settings were altered by increasing the window width, the for- JR:178, March 2002 Fig year-old woman who stepped on toothpick 7 days before imaging., Spin-echo T1-weighted axial MR image (TR/TE, 700/20) of forefoot shows retained wooden foreign body as focal signal void (open arrow) with surrounding hypointense inflammatory reaction (solid arrow)., Corresponding spin-echo T2-weighted axial MR image (2,000/90) depicts retained wood as signal void (open arrow) with hyperintense surrounding foreign body granulomatous response (solid arrow). eign bodies were more easily identified. Previous authors have suggested using wide window widths up to 1,000 H with a level of 500 H for optimization of detection [5]. The attenuation of a retained wooden foreign body varies in relation to the content of air and fluid in the interstices of the wood. When dry wood enters the body, it is predominantly filled with air. Within approximately 1 week, the wood absorbs surrounding blood products and exudate and increases its attenuation [6]. In addition, different types of wood have been shown to have variable attenuations, and surface coating such as paint or sealant will affect the degree and timing of this increase in attenuation [7]. Dry wood, with a high air content, has been reported to mimic a gas collection [5]. The attenuation values for smaller objects may vary relating to partial volume averaging. When compared with MR imaging, CT has the advantage of being less expensive, more readily available, and faster to perform [7]. The identification of wooden foreign bodies may be exceedingly difficult on MR imaging, especially when foreign bodies are small and there is no associated abscess or fluid collection. In such cases, the foreign body may appear as a signal void with surrounding nonspecific granulation tissue. In this series, all foreign bodies appeared hypointense on all se- 559

, Three-dimensional surface rendered CT scan of foot shows retained wooden foreign body within soft tissue between first and second metatarsals.

Retained wood, in contrast to metal, does not reveal susceptibility artifact, and linear signal voids may be mistaken for tendons or dense collagenous structures (Fig. 2).

4 Downloaded from by on 01/23/18 from IP address Copyright RRS. For personal use only; all rights reserved Peterson et al. Fig year-old girl who presented for 2 years with intermittently draining sinus on dorsum of foot at site of previous surgery for ganglion., Sagittal short tau inversion recovery MR image shows hypointense retained wooden foreign body with surrounding highsignal inflammatory response., Three-dimensional surface rendered CT scan of foot shows retained wooden foreign body within soft tissue between first and second metatarsals. C, Gross specimen photograph depicts toothpick removed at surgery. C quences. Two cases showed the lesions to be signal voids. Retained wood, in contrast to metal, does not reveal susceptibility artifact, and linear signal voids may be mistaken for tendons or dense collagenous structures (Fig. 2). It has been reported with MR imaging, just as with CT, that wood in soft tissue may absorb the surrounding hematoma and exudate, prolonging T1 and T2 relaxation times [1]. Some degree of surrounding inflammatory tissue is usually associated with a foreign body. In the acute setting, surrounding hemorrhage and hematoma may be seen, being replaced in time with granulomatous tissue. 560 In this study, the inflammatory reaction associated with retained wood showed prolonged T1 and T2 relaxation times and prominent contrast enhancement. Identification of the inflammatory response can assist the viewer in identifying the retained foreign body because the actual splinter may be difficult to visualize. The surrounding foreign body reaction may be mistaken for a soft-tissue mass or a tumor if the central foreign body is not identified [8]. Sonography has been well studied in the evaluation of retained foreign bodies and has proved both sensitive and specific [9, 10]. Given the markedly different acoustic impedance of wood and soft tissues, retained wooden foreign bodies are easily identified, with the leading edge of the echogenic wood resulting in marked acoustic shadowing [11] (Figs. 4 and 5). Sonography proved to be the best modality in the detection of retained wooden foreign bodies. However, the evaluation was often performed to confirm findings first seen on other modalities. In our experience, only 25% of patients presented with a history of penetrating injury. In patients presenting with nonspecific pain and swelling, MR imaging or CT is often performed first to JR:178, March 2002

, Spin-echo T2-weighted axial MR image (TR/TE, 2,716/80) of right thigh reveals retained wooden foreign body (asterisk) in right vastus lateralis muscle.

, Sagittal short tau inversion recovery MR image (2,300/30; inversion time, 150 msec) shows foreign body as signal void with surrounding hyperintense granulomatous response.

D, Gross specimen photograph shows large twig removed at surgery. evaluate for the presence of an underlying mass or inflammatory process.

5 Downloaded from by on 01/23/18 from IP address Copyright RRS. For personal use only; all rights reserved Wooden Foreign odies C D Fig. 4. Retained wooden foreign body with abscess and draining sinus tract in 49-year-old man who fell off roof into foliage several months earlier., Spin-echo T2-weighted axial MR image (TR/TE, 2,716/80) of right thigh reveals retained wooden foreign body (asterisk) in right vastus lateralis muscle. Hypointense retained wood is seen centrally with surrounding hyperintense inflammatory response., Sagittal short tau inversion recovery MR image (2,300/30; inversion time, 150 msec) shows foreign body as signal void with surrounding hyperintense granulomatous response. Note associated cellulitis and sinus tract extending through subcutaneous adipose tissue. C, Gray-scale sonogram shows hyperechoic retained wooden foreign body with associated acoustic shadowing. D, Gross specimen photograph shows large twig removed at surgery. evaluate for the presence of an underlying mass or inflammatory process. t our institution, if there is any reason to suspect a retained foreign body or if an equivocal case imaged with another modality presents, sonography is routinely performed. When compared with MR imaging or CT, sonography is less expensive, more readily available, and superior in the detection of small wooden foreign bodies. Sonography is the modality of choice in patients who present with a history of antecedent skin puncture or when a penetrating injury is suspected. rthrography may be helpful in cases in which the wooden foreign body has pene- JR:178, March 2002 trated a joint cavity. In one patient in our series, the retained wooden foreign body penetrated the elbow joint. Distention of the elbow joint with contrast material showed marked irregularity of the synovium consistent with reactive synovitis (Fig. 1), which was also seen on contrast-enhanced MR imaging. If intraarticular, the foreign body may be identified on arthrography as a filling defect in the contrast-filled joint. When a soft-tissue mass is seen and there is a possibility of a retained foreign body, the shape of the lesion can be helpful. On crosssectional imaging, retained wooden foreign bodies tend to be cylindric with a long length and minimal width. Imaging perpendicular to the foreign body often reveals a target appearance with the central foreign body appearing as a signal void or hypointense area in contrast to the surrounding hyperintense inflammatory tissue [3] (Figs. 2 and 4). If a wooden splinter is large and the slice thickness is thin, the lesion can be seen in a profile that allows a confident diagnosis (Fig. 3). Unfortunately, imaging parallel to a thin foreign body with thick slices or a large gap may miss the wood completely and render the foreign body inconspicuous. In summary, the detection of retained wooden foreign bodies can be exceedingly dif- 561

Peterson et al. Downloaded from www.ajronline.org by 37.44.194.233 on 01/23/18 from IP address 37.44.194.233. Copyright RRS. For personal use only; all rights reserved Fig. 5.

, Sagittal reformatted CT scan of forefoot shows hyperdense retained wooden foreign body in plantar soft tissues of foot.

6 Peterson et al. Downloaded from by on 01/23/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with draining sinus tract on plantar aspect of foot with multiple prior débridements with history of penetrating trauma 2 years earlier., Sagittal reformatted CT scan of forefoot shows hyperdense retained wooden foreign body in plantar soft tissues of foot., Sonogram of foot shows retained wooden foreign body with hyperechoic leading edge and obscuration of trailing edge by acoustic shadowing. ficult because patients typically present with nonspecific symptoms without a reported history of penetrating injury. Radiographs are frequently the first study obtained, but they are usually unremarkable. MR imaging and CT are often performed to evaluate nonspecific symptoms; however, accurate identification of retained wood with these modalities can be difficult. Wood usually shows a linear hypointense signal on MR imaging with an associated inflammatory mass. CT typically shows the retained wood as a linear area of increased attenuation, which is best seen on wide window settings. Sonography has proved the most useful modality, easily identifying the retained wood as a linear echogenic focus with marked acoustic shadowing. Unfortunately, sonography is often underused if the appropriate history is not presented. t our institution, if there is any reason to suspect a retained wooden foreign body, sonography is routinely performed. Radiologists need to be aware of the various imaging appearances of wooden foreign bodies and should be able to successfully localize the retained wood if the appropriate history is obtained. References 1. Ochiai H, Yamakawa Y, Fukushima T, Yamada H. Neuroimaging of a wooden foreign body retained for 5 months in the temporalis muscle following penetrating trauma with a chopstick. Neurol Med Chir 1998;39: nderson M, Newmeyer WL, Kilgore ES. Diagnosis and treatment of retained foreign bodies in the hand. m J Surg 1982;144: Monu JU, McManus CM, Ward WG, Haygood TM, Pope TL, ohrer SP. Soft-tissue masses caused by long-standing foreign bodies in the extremities: MR imaging findings. JR 1995;165: Laor T, arnewolt CE. Nonradiopaque penetrating foreign body: a sticky situation. Pediatr Radiol 1999;29: Ho VT, McGuckin JF, Smergel EM. Intraorbital wooden foreign body: CT and MR appearance. JNR 1996;17: Ginsberg LE, Williams DW, Mathew VP. CT in penetrating craniocervical injury by wooden foreign bodies: reminder of a pitfall. JNR 1993;14: McGuckin JF, khtar N, Ho VT, Smergel EM, Kubacki EJ, Villafana T. CT and MR evaluation of a wooden foreign body in an in vitro model of the orbit. JNR 1996;17: Ferguson PC, ell RS, Davis M. Foreign-body abscesses presenting as soft tissue tumors: two case reports. Can J Surg 1994;37: Mizel MS, Steinmetz ND, Trepman E. Detection of wooden foreign bodies in muscle tissue: experimental comparison of computed tomography, magnetic resonance imaging and ultrasonography. Foot nkle Int 1994;15: Horton LK, Jacobson J, Powell, Fessell DP, Hayes CW. Sonography and radiography of softtissue foreign bodies. JR 2001;175: Fornage D, Schernberg FL. Sonographic diagnosis of foreign bodies of the distal extremities. JR 1986;147: JR:178, March 2002

International Journal of Research in Health Sciences ISSN: Available online at: Case Study

International Journal of Research in Health Sciences ISSN: 2321-7251 Available online at: http://www.ijrhs.org/ Case Study Foreign body granuloma mimicking a soft tissue neoplasm *Rohan Sawant, Abhishek