Normal Postoperative Changes Research Articles

Temporal changes in magnetic resonance imaging characteristics of Gliadel wafers and of the adjacent brain parenchyma

Carmustine is used in the treatment of glioblastomas as locally applied chemotherapy in the form of biodegradable wafers, which are lined on the walls of the resection cavity at the end of the resection, to increase local concentrations and decrease systemic toxicity. A total of 44 patients with glioblastoma with gross macroscopic tumor removal were included. MRIs were performed at various times postoperatively (within 24 hours, 1 week, 1 month, 2 months, 3 months, 6 months, 9 months, and 1 year). MR protocols included a T2-, diffusion-weighted, and T1-weighted sequences with and without intravenous administration of gadolinium. On T1, the wafers change from their initial hypointense to an isointense appearance after a period during which they appear to be hypointense, with a hyperintense rim most prominent less than 1 month postoperatively. On T2 they change from a hypointense to an isointense appearance. Restricted diffusivity reshaping the silhouette of the wafer's surface at the rim of the resection cavity can be found as early as day 1 postoperatively; however, 1 month after implantation, they all show areas of restricted diffusion, which may remain up to 1 year. Contrast enhancement at the rim of the resection cavity can already be found at day 1 postoperatively, with a peak shortly after 1 month after surgery. These changes can easily be mistaken for an abscess and hamper the early differentiation between residual tumor tissue and normal postoperative changes. However, early changes in either appearance do not predict overall survival or the progression free interval.

Normal and Pathologic Features of the Postoperative Biliary Tract at 3D MR Cholangiopancreatography and MR Imaging

Magnetic resonance (MR) imaging with cholangiopancreatographic sequences plays a critical role in evaluating alterations in the biliary tract after surgical procedures such as cholecystectomy, liver transplantation, hepatic resection, and the creation of a biliary-enteric anastomosis. MR cholangiopancreatography, a rapid, noninvasive, and accurate imaging technique for the assessment of early and late complications of hepatobiliary surgery, usually enables the identification of normal and abnormal postoperative changes. In cases of complete obstruction of the bile duct, MR cholangiopancreatography allows analysis of the biliary tract above and below the level of the obstruction, a capability essential for treatment planning and one that is not provided by either endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography. MR cholangiopancreatography is particularly useful for the evaluation of biliary-enteric anastomoses, for which an endoscopic approach is generally precluded. It also can help detect and localize bile duct strictures and stones and can help accurately classify bile duct injuries. It is useful for detecting bile leaks, although it generally does not directly depict the extravasation of bile. In addition to MR cholangiopancreatography, T1- and T2-weighted MR imaging may be performed to depict extrabiliary soft-tissue structures and abnormalities such as an abscess, tumor recurrence or metastasis, hematoma, or hemobilia. Mangafodipir trisodium-enhanced MR cholangiopancreatography, a recently developed technique that provides a combination of anatomic and functional information, is particularly helpful for documenting bile leaks because it allows a functional evaluation of biliary excretion and may directly depict bile leakage from injured ducts.

Zolpidem Tartrate Use as Contributory Factor in Sinus Disease

849 DEAR EDITOR, WE WRITE TO SHARE OUR EXPERIENCE WITH A PATIENT WHO EXHIBITED SYMPTOMS OF CHRONIC RHINOSINUSITIS DUE TO ZOLPIDEM TARTRATE USE. THIS patient’s nasal congestion, sinus pressure, and headache resolved with the discontinuation of zolpidem tartrate. Our MEDLINE search coupling the terms zolpidem tartrate and Ambien with sinusitis, rhinitis, rhinosinusitis, nasal congestion, rhinorrhea, allergy and otolaryngology revealed no published association. However, inquiry to Sanofi-Aventis revealed that cases of sinus complaints in association with zolpidem tartrate use have been reported. In this instance, a 55-year-old female nonsmoker was unsuccessfully treated for 12 years for symptoms of chronic rhinosinusitis. Her past medical history revealed asthma, mitral valve prolapse, multinodular goiter, osteoporosis, gastroesophageal reflux disease, and insomnia. She originally described symptoms of nasal congestion, sinus pressure, and headache and complained of recurrent sinus infections characterized by increased facial pain, mucopurulent discharge, postnasal drip, cough, and low-grade fevers with malaise. Skin testing was positive only to hormodendrum, and immunologic work-up was negative. Initial medical therapy with nasal decongestants, allergy medications, and courses of antibiotics failed to resolve her symptoms. She underwent functional endoscopic sinus surgery, septoplasty, and bilateral partial inferior turbinectomy in 1993. Despite an initial improvement, her nasal congestion and headaches soon returned. Endoscopic examinations demonstrated well-healed postoperative paranasal sinus cavities. Computed tomography scans showed normal postoperative changes in the paranasal sinuses. Her symptoms persisted despite medical therapy by neurology, allergy, and pulmonary consultants for presumed contributing factors of migraines and allergic rhinitis. The patient’s symptoms completely resolved upon discontinuing her long-term zolpidem tartrate (Ambien) therapy for insomnia. She has been symptom free and off all rhinosinusitis and headache medications for 9 months. Zolpidem tartrate is a nonbenzodiazepine, nonbarbiturate hypnosedative that is “the #1 prescribed sleep aid in America,” having largely replaced the benzodiazepine class as pharmacologic therapy for insomnia and related disorders. 1 Zolpidem was first introduced in France in 1992 under the trade name Stilnox, followed by marketing in the United States as Ambien. Hypnosedative drugs act on the g-aminobutyric acid (GABA) receptor complex to produce their sedative effects. The classic benzodiazepine drugs act nonselectively on both the ω 1 and ω 2 GABA A receptorbinding sites, producing both sedation and memory/cognition effects, respectively. Zolpidem acts selectively on the ω 1 receptor of the GABA A molecule, thereby producing sedation similar to that of the benzodiazepines but without the side effects of memory impairment. 2,3 It is quickly absorbed and distributed, reaches peak plasma levels in 1.5 hours, and has a short half-life of 1 to 2.4 hours. 2 Thus, it works rapidly to induce and maintain sleep but has few after-effects of daytime somnolence after a full 7 to 8 hours of sleep. Side effects and adverse reactions with the use of zolpidem are reported to occur in 1% to 30% of patients. The most common adverse reactions are central nervous system-related, with headache as the dominant complaint (19% to 28.4%), followed by drowsiness (8% to 16.6%). 2-6 Other adverse effects include dizziness, vertigo, dry mouth and bitter or metallic taste, nausea, emesis, dyspepsia, diarrhea, myalgias, and arthralgias. Various psychiatric complaints of anxiety, confusion, depression, nightmares, and hallucinations have been reported. 2-6 In our review of the published literature, we found no report of any rhinologic side effects of zolpidem; a related nonbenzodiazepine hypnosedative, zaleplon, is reported in the pharmacology literature as infrequently causing rhinitis and pharyngitis symptoms. 2 However, the manufacturing company of zolpidem, Sanofi-Aventis, reports that symptoms of rhinosinusitis can occur in patients treated with zolpidem. According to the detailed drug information available on their web site, the incidence of rhinosinusitis in patients on zolpidem is 4%, compared with 2% in the placebo group. Rhinitis is reported in 1% (placebo 3%), upper respiratory infection symptoms in 5% (placebo 6%), and pharyngitis symptoms in 3% (placebo 1%). 4 A mechanism of action for zolpidem and related sedative-hypnotics to produce these sinonasal complaints has not yet been described. Bateman and Woolford reviewed multiple drug classes for their rhinologic side effects and noted that one drug of the hypnotic class, chlomethiazole, may cause rhinitis. Other central nervous system medications are noted to produce sinonasal complaints due to the widespread effect of these drugs on the various neurotransmitter systems of the central nervous system, including those of the autonomic nervous system. The α- and β-blocking properties of many of these drugs interfere with the normal sympathetic tone of the sinonasal mucosa. The drugs cause vasodilation and mucosal engorgement, producing symptoms of congestion and rhinorrhea. This theory has not, however, been applied to the hypnosedative class, nor to other psychiatric drug classes known to produce sinonasal complaints, such as the selective serotonin-specific reuptake inhibitors, antiepileptics, and anti-Parkinson drugs. 7

Zolpidem Tartrate Use as Contributory Factor in Sinus Disease

849 DEAR EDITOR, WE WRITE TO SHARE OUR EXPERIENCE WITH A PATIENT WHO EXHIBITED SYMPTOMS OF CHRONIC RHINOSINUSITIS DUE TO ZOLPIDEM TARTRATE USE. THIS patient’s nasal congestion, sinus pressure, and headache resolved with the discontinuation of zolpidem tartrate. Our MEDLINE search coupling the terms zolpidem tartrate and Ambien with sinusitis, rhinitis, rhinosinusitis, nasal congestion, rhinorrhea, allergy and otolaryngology revealed no published association. However, inquiry to Sanofi-Aventis revealed that cases of sinus complaints in association with zolpidem tartrate use have been reported. In this instance, a 55-year-old female nonsmoker was unsuccessfully treated for 12 years for symptoms of chronic rhinosinusitis. Her past medical history revealed asthma, mitral valve prolapse, multinodular goiter, osteoporosis, gastroesophageal reflux disease, and insomnia. She originally described symptoms of nasal congestion, sinus pressure, and headache and complained of recurrent sinus infections characterized by increased facial pain, mucopurulent discharge, postnasal drip, cough, and low-grade fevers with malaise. Skin testing was positive only to hormodendrum, and immunologic work-up was negative. Initial medical therapy with nasal decongestants, allergy medications, and courses of antibiotics failed to resolve her symptoms. She underwent functional endoscopic sinus surgery, septoplasty, and bilateral partial inferior turbinectomy in 1993. Despite an initial improvement, her nasal congestion and headaches soon returned. Endoscopic examinations demonstrated well-healed postoperative paranasal sinus cavities. Computed tomography scans showed normal postoperative changes in the paranasal sinuses. Her symptoms persisted despite medical therapy by neurology, allergy, and pulmonary consultants for presumed contributing factors of migraines and allergic rhinitis. The patient’s symptoms completely resolved upon discontinuing her long-term zolpidem tartrate (Ambien) therapy for insomnia. She has been symptom free and off all rhinosinusitis and headache medications for 9 months. Zolpidem tartrate is a nonbenzodiazepine, nonbarbiturate hypnosedative that is “the #1 prescribed sleep aid in America,” having largely replaced the benzodiazepine class as pharmacologic therapy for insomnia and related disorders. 1 Zolpidem was first introduced in France in 1992 under the trade name Stilnox, followed by marketing in the United States as Ambien. Hypnosedative drugs act on the g-aminobutyric acid (GABA) receptor complex to produce their sedative effects. The classic benzodiazepine drugs act nonselectively on both the ω 1 and ω 2 GABA A receptorbinding sites, producing both sedation and memory/cognition effects, respectively. Zolpidem acts selectively on the ω 1 receptor of the GABA A molecule, thereby producing sedation similar to that of the benzodiazepines but without the side effects of memory impairment. 2,3 It is quickly absorbed and distributed, reaches peak plasma levels in 1.5 hours, and has a short half-life of 1 to 2.4 hours. 2 Thus, it works rapidly to induce and maintain sleep but has few after-effects of daytime somnolence after a full 7 to 8 hours of sleep. Side effects and adverse reactions with the use of zolpidem are reported to occur in 1% to 30% of patients. The most common adverse reactions are central nervous system-related, with headache as the dominant complaint (19% to 28.4%), followed by drowsiness (8% to 16.6%). 2-6 Other adverse effects include dizziness, vertigo, dry mouth and bitter or metallic taste, nausea, emesis, dyspepsia, diarrhea, myalgias, and arthralgias. Various psychiatric complaints of anxiety, confusion, depression, nightmares, and hallucinations have been reported. 2-6 In our review of the published literature, we found no report of any rhinologic side effects of zolpidem; a related nonbenzodiazepine hypnosedative, zaleplon, is reported in the pharmacology literature as infrequently causing rhinitis and pharyngitis symptoms. 2 However, the manufacturing company of zolpidem, Sanofi-Aventis, reports that symptoms of rhinosinusitis can occur in patients treated with zolpidem. According to the detailed drug information available on their web site, the incidence of rhinosinusitis in patients on zolpidem is 4%, compared with 2% in the placebo group. Rhinitis is reported in 1% (placebo 3%), upper respiratory infection symptoms in 5% (placebo 6%), and pharyngitis symptoms in 3% (placebo 1%). 4 A mechanism of action for zolpidem and related sedative-hypnotics to produce these sinonasal complaints has not yet been described. Bateman and Woolford reviewed multiple drug classes for their rhinologic side effects and noted that one drug of the hypnotic class, chlomethiazole, may cause rhinitis. Other central nervous system medications are noted to produce sinonasal complaints due to the widespread effect of these drugs on the various neurotransmitter systems of the central nervous system, including those of the autonomic nervous system. The α- and β-blocking properties of many of these drugs interfere with the normal sympathetic tone of the sinonasal mucosa. The drugs cause vasodilation and mucosal engorgement, producing symptoms of congestion and rhinorrhea. This theory has not, however, been applied to the hypnosedative class, nor to other psychiatric drug classes known to produce sinonasal complaints, such as the selective serotonin-specific reuptake inhibitors, antiepileptics, and anti-Parkinson drugs. 7

Imaging After a Whipple Operation

Spiral computed tomography (CT) examination of patients after a Whipple operation often raises questions concerning the afferent loop. This study evaluates the efficiency of biliary contrast medium (BCM) in visualizing opacification of this loop. After undergoing a Whipple operation, 31 patients received 100 mL BCM before postoperative spiral CT (Somatom Plus 4; Siemens, Erlangen, Germany: 5- or 10-mm slices, feed of 7 or 12 mm/s; Volume Zoom; Siemens: 2.5 mm collimation, total feed of 15 mm/s). Semiquantitative evaluation included opacification of the jejunal loop and visibility of jejunostomies. Complications and tumor recurrences were recorded. In all patients, BCM was successfully administered without complications. Afferent loop opacification was seen in 95% of examinations with BCM versus 5% of examinations with oral contrast medium. Evaluation of jejunostomies was unequivocally facilitated by BCM. Three previously undetermined changes were identified as tumor recurrence, and recurrence was ruled out after examination with BCM in 7 cases. After a Whipple operation, opacification of the afferent loop can be regularly achieved by intravenous administration of BCM, which eases distinction of normal postoperative changes from local tumor recurrence. Administration of BCM is recommended as a standard diagnostic procedure in these patients.

Color Doppler US of the Postoperative Penis: Anatomy and Surgical Complications

A number of surgical procedures that significantly change the penile anatomy and vasculature can be used to manage pathologic conditions of the penis (eg, congenital and acquired deformities, erectile dysfunction, priapism). Phallic reconstruction surgery can be used for sex reassignment and after penile amputation or for correction of congenital malformations. Color Doppler ultrasonography (US) clearly depicts the normal penile anatomy and postoperative changes (eg, changes of the tunica albuginea, extraalbugineal pathologic fluid collections, cavernosal tissue changes produced by scars and fibrosis). It is also effective in evaluating surgery-related complications and determining the causes of erectile dysfunction and other unsatisfactory long-term results. Moreover, color Doppler US of the penile vessels and vascular anastomoses following revascularization allows direct evaluation of flow characteristics, shunt patency, and venous engorgement. Color Doppler US is the imaging modality of choice in evaluating patients who have undergone penile surgery.

Postoperative anatomic and pathologic findings at CT following colonic resection

CT is frequently used for postoperative evaluation in patients who have undergone colonic resection. This pictorial article reviews and demonstrates the CT findings of normal postoperative anatomic changes, as well as different postoperative complications following various colonic operative techniques.

Scintimammography: a pictorial review of the variable normal, post surgical and pathological appearances

Scintimammography has a high specificity and sensitivity for the detection of primary and metastatic breast carcinoma and in the evaluation of the postoperative breast. This review highlights the spectrum of pathological features as well as the normal postoperative and postreconstruction changes and the variable normal appearances that may be encountered with this technique.

The role of preliminary interpretation of chest radiographs by radiographers in the management of acute medical problems within a cardiothoracic centre

Radiographic staff in a regional cardiothoracic centre were asked to assess all pre- and post-operative chest radiographs over a 6-month period. Radiographs showing new, acute changes were noted and a red dot placed on the film. Medical staff were notified of radiographs with red dots, and these were subsequently reported by radiologists. Using reports by radiologists as the gold standard, an audit was performed of the radiographers' accuracy in identifying new abnormalities. The absence of a necessary red dot as well as inappropriate use were noted. To enhance the accuracy of radiograph interpretation, a series of lectures on the chest radiograph and a protocol for red dot use were developed by senior radiologists. During this 6-month period 8614 chest radiographs were taken; red dots were applied to 464 (5%). These red dots were considered incorrect in 100 radiographs. Radiographers misinterpreted or missed potentially important changes in 38 of the remaining 8150 radiographs without red dots (sensitivity and specificity of 90% and 99%, respectively). Radiographers appeared to err on the side of caution when confronted with an abnormal chest radiograph, especially when previous radiographs and reports were unavailable. This resulted is a relatively high false positive rate. Future audits will show whether this rate can be reduced by continued training. Subtle interpretation is crucial to distinguish between an abnormal chest radiograph needing urgent medical attention and an abnormal chest radiograph with normal post-operative changes. The opinion of the experienced and trained radiographer is immediate and may be invaluable to the diagnostic care of the patient.

Intra-operative MR guidance during trans-sphenoidal pituitary resection: Preliminary results

The use of intra-operative MR image guidance has the potential to improve the precision, extent, and safety of trans-sphenoidal pituitary resections. The trans-sphenoidal approach to pituitary surgery has been performed for some time (1--3). Until now these surgeries have relied on direct visualization without the aid of image guidance. An open-bore configuration 0.5T SIGNA SP MR system (GE Medical Systems, Milwaukee, Wisconsin) has been used to provide image guidance for seventeen trans-sphenoidal pituitary adenoma resections (4). The intra-operative MRI system allowed the radiologist to successfully direct the surgeon toward the sella turcica while avoiding the cavernous sinus, optic chiasm and other critical structures. Imaging performed during the surgery monitored the extent of resection and allowed for removal of tumor beyond the surgeon's view in seven cases. Dynamic MR imaging was used to distinguish residual tumor from normal gland and postoperative changes, permitting more precise tumor localization. A heme-sensitive long TE gradient echo sequence was used to find the presence of hemorrhagic debris. All patients tolerated the procedure well without significant complications. J. Magn. Reson. Imaging 2001;13:136-141.

Role of radionuclide imaging in the diagnosis of postoperative infection.

Postoperative infections are a serious cause of morbidity and mortality and are difficult to diagnose. Signs and symptoms that are generally associated with infection may be masked by, or mistaken for, normal postoperative changes. Anatomic imaging modalities provide high-quality anatomic detail and are the procedures of choice in affected patients because of their availability, ease of performance, accuracy, and value in the selection of treatment options. However, radionuclide studies demonstrate physiologic processes, which often precede anatomic changes, and can help distinguish normal postoperative inflammation from infection. Radionuclide studies are also useful in identifying complicated orthopedic infections, in which the often extensive distortions produced by metallic hardware can confound the interpretation of anatomic images. Of the three agents (gallium-67 citrate, indium-111-labeled leukocytes, technetium-99m-labeled leukocytes) that are currently approved in the United States for imaging of infection, In-111-labeled leukocyte imaging is the procedure of choice for diagnosing postoperative infection. Gallium scintigraphy is best reserved for those situations in which leukocyte imaging is not available or there is concern that the suspected infection may not incite a neutrophil response. In general, the value of radionuclide imaging is maximized when used only in those patients for whom the results of anatomic imaging are negative, nondiagnostic, or at odds with the clinical impression.

Postoperative Pattern of Various Hormonal and Metabolic Variables. A Pilot Study in Patients Without Complications Following Cardiac Surgery

SummaryThe use of single predictors for threatening postoperative complications are widely accepted. However, a typical pattern of multiple parameters could be more helpful than a single predictor. To study this hypothesis, various variables of normal postoperative changes in patients without postoperative complications were investigated. Secondly, this pattern needs to be compared in the future with those findings in patients with postoperative complications.Blood parameters of 13 patients undergoing cardiovascular surgery without postoperative complications for 24 hours were evaluated. Samples were obtained on the afternoon before the operation and 1,3, 6,12 and 24 hours after the end of surgey.At one hour postoperation increased levels of the following parameters were noted: growth hormone (p < 0.0001), glucose (p < 0.0001), insulin (p < 0.001), c-peptide (p < 0.001), lactate (p < 0.002), glutamate (p < 0.0001), aspartate (p < 0.001) and total amino acids (p < 0.07), although the concentration of some amino acids decreased. Three hours postoperatively free fatty acids (p < 0.05) were increased. Total-T3 concentrations were reduced postoperatively. Other parameters were not altered. Most of the parameters returned to normal values during the period of observation.

MR-appearance of the pituitary gland before and after resection of pituitary macroadenomas

Pituitary macroadenomas can cause severe compression and displacement of the pituitary gland. This study was undertaken to determine the value of contrast administration for the detection of the pituitary gland in patients with pituitary macroadenomas, to evaluate the preoperative location and configuration of the pituitary gland and to describe its postoperative changes after tumour resection. Preoperative and postoperative MR imaging examinations of 30 patients with histologically proven pituitary macroadenomas were retrospectively evaluated. The examinations were performed on a 1.5 T unit, by obtaining T1-weighted sagittal and coronal images after administration of gadopentetate dimeglumine. On preoperative MR images, contrast administration increased the detectability of the anterior lobe from 30% to 80%. Depending on the size and extension of the adenoma, the pituitary gland was displaced to the suprasellar space (53%) and/or deformed to a club-shaped (27%) or sickle-shaped (47%) configuration. In six patients, the sickle-shaped pituitary gland was interposed between the cavernous sinus and the adenoma ('rim-sign'), which was seen only on gadopentetate dimeglumine-enhanced images. In these cases, there was no infiltration of the cavernous sinus at surgery. Postoperatively, descent of the pituitary gland was found in 63%, and reexpansion in 54%. We conclude that contrast administration improves the detectability of the pituitary gland on preoperative MR images, and that the displacement and deformation of the pituitary gland depend on the size, location and extension of the adenoma. Preoperatively, demonstration of the pituitary gland interposed between the cavernous sinus and the adenoma ('rim-sign') is a very useful sign for exclusion of cavernous sinus infiltration, best seen on contrast-enhanced coronal MR images. The normal postoperative changes of the pituitary gland after tumour resection include repositioning and re-expansion.

Transient mutism after posterior fossa surgery

An 8-year-old girl developed mutism after removal of a vermian medulloblastoma. The mutism was not accompanied by long tract signs or cranial nerve palsy. The girl started to regain her speech 2 weeks postoperatively, showing marked improvement 2 months after the operation, after passing through a dysarthric phase. Magnetic resonance imaging showed only normal postoperative changes without abnormalities of dentate nuclei or supranuclear region. Nineteen similar cases of transient mutism following cerebellar operations have been reported in the literature, most of them with a delayed postoperative onset. In all patients the recovery of speech started to appear 4 days to 4 months postoperatively, and all patients passed through a monotonous, dysarthric phase. The absence of long tract or other brain stem signs, together with the presence of dysarthria during the recovery of speech, suggested a cerebellar cause of the transient mutism. Various hypotheses advanced to explain the pathogenesis of this speech disorder are analyzed.

Postoperative diskitis: distinguishing early MR imaging findings from normal postoperative disk space changes.

To distinguish early magnetic resonance (MR) imaging findings in postoperative diskitis from normal postoperative changes, a prospective study was performed in 15 asymptomatic patients (17 disk levels) who underwent uncomplicated lumbar diskectomy and seven patients with proved postoperative diskitis. On postoperative MR images, four of the asymptomatic patients had a finding that could also be seen in patients with diskitis. Gadolinium enhancement was useful in making the distinction and occurred as follows: (a) vertebral bone marrow: all seven diskitis patients and one asymptomatic patient; (b) disk space: five diskitis patients and three asymptomatic patients; and (c) posterior anulus fibrosus: all seven diskitis patients and 13 asymptomatic patients (14 of 17 levels). This entire triad of findings, which is strongly suggestive of postoperative diskitis, was not seen in any of the asymptomatic patients. Changes in the disk space and adjacent bone marrow on pre- and post-contrast MR images after routine diskectomy are uncommon and should not be assumed to be normal postoperative changes without careful consideration and analysis for early diskitis.

Imaging of the postoperative lumbar spine

Abstract The failed back surgery syndrome is characterized by intractable pain and varying degrees of disability after spine surgery. The most important task of postoperative imaging is to distinguish conditions that will benefit from surgery from those that will not be improved with another operation. Plain radiographs are important for obtaining a set of basic information about the previously operated levels and overall alignment of the spine. After excluding mechanical instability, bony stenosis, and arachnoiditis, one of the most crucial diagnostic distinctions is that of epidural scar from recurrent or residual herniated disc. Unenhanced CT can make this assessment in 43% to 60% of the cases. The addition of IV contrast to CT increases the diagnostic accuracy to 70% to 83%. Unenhanced MR has a similar accuracy to that of CT with contrast, 76% to 89%. Gadolinium-enhanced MR may further increase the ability to identify scar and disc material noninvasively. With any of these imaging modalities it is essential to distinguish normal postoperative changes from findings that result in persistent or recurrent symptoms. As with preoperative imaging studies, these tests should not be used to screen, but rather to confirm diagnoses based on clinical information. Extreme caution must be exercised to avoid overinterpretation of postoperative imaging abnormalities that do not correspond anatomically to the patient's symptoms.

Left ventricular diastolic function. Doppler echocardiographic changes soon after cardiac transplantation.

In acute cardiac rejection, left ventricular diastolic function is altered, and a restrictive ventricular filling pattern occurs. Doppler echocardiographic indexes of mitral inflow have been proposed as sensitive markers of the rejection process. As rejection progresses, the restrictive ventricular filling pattern is reflected by a shortening of isovolumic relaxation time and mitral valve pressure half-time and by an increase in early transmitral filling velocity. Diastolic function is also compromised in the nonrejecting cardiac transplant recipient during the early postoperative period. This study examined the progression in Doppler-derived mitral filling indexes in 25 recent cardiac transplant recipients who demonstrated no histological evidence of transplant rejection. Isovolumic relaxation time, mitral valve pressure half-time, and early transmitral filling velocity were measured at postoperative weeks 1, 2, 4, and 6 on the day that surveillance right ventricular endomyocardial biopsies were performed. The initial indexes were comparable to previously described restrictive parameters and over the 6-week study period evolved into a nonrestrictive filling pattern. This evolution reflects a progressive improvement in postoperative diastolic function and a decrease in left heart filling pressures. None of the evaluated clinical characteristics, including preoperative pulmonary pressures, total ischemic time of the transplanted heart, cardiopulmonary bypass time, and age of the donor heart, correlated with this process. Given the increasing use of Doppler echocardiography as a means of screening for transplant rejection, it is important to have a thorough understanding of normal postoperative changes in left ventricular diastolic function.

Incorporation versus infection of retroperitoneal aortic grafts: MR imaging features.

The magnetic resonance (MR) imaging characteristics of normal aortic graft healing were compared with those of perigraft infection in 57 patients after aortic graft implantation. Thirty-three patients without postoperative complications underwent MR imaging in a 0.35-T unit 1 week after graft implantation, and 13 of those patients were reexamined 2-3 months after graft implantation. Twenty-four patients with clinically suspected perigraft infection underwent MR imaging 6 weeks to 18 years after graft implantation. Early normal postoperative changes were characterized by a perigraft collar of low to medium signal intensity on T1-weighted images and of high intensity on T2-weighted images in all 33 cases, consistent with perigraft fluid collection. In 10 of 13 patients reexamined 2-3 months postoperatively, the MR images demonstrated a collar of tissue consistent with perigraft fibrosis. In cases of clinical suspicion of retroperitoneal graft infection, MR imaging showed eccentric fluid collections of low to medium signal intensity on T1-weighted images and high intensity on T2-weighted images at more than 3 months after surgery. The MR findings were diagnostic of retroperitoneal perigraft infection in 17 of 20 patients shown to be infected at surgery. Retroperitoneal infection was correctly excluded on the basis of MR findings in four patients. Thus, MR imaging is an accurate imaging method for the diagnosis of aortic graft infection. In the early postoperative phase, resolving perigraft fluid cannot be differentiated from perigraft infection.

Chest wall after mastectomy. Part I. CT appearance of normal postoperative anatomy, postirradiation changes, and optimal scanning techniques.

The computed tomographic (CT) scans of patients with breast carcinoma treated by surgery with and without radiation therapy were reviewed and correlated with clinical status. The optimal techniques of patient examination and the post-therapy findings were analyzed. The brachial injection of intravenous contrast material produced significant artifacts that limited interpretation of the ipsilateral chest wall in all cases and did not give additional information. Scans obtained with the patients' arms placed at their sides resulted in more clearly interpretable scans, especially when arm weakness or lymphedema precluded symmetric elevation of the arms out of the CT gantry. Radiation therapy produced both acute and chronic changes with characteristic CT appearances. The postoperative anatomy varied markedly depending on the previous surgery. Careful clinical correlation with referring physicians was the key to proper scan evaluation.

The neck after total laryngectomy: CT study.

Computed tomographic scans in 23 patients who had undergone total laryngectomy were analyzed retrospectively to determine normal postoperative appearance and to evaluate the role of CT in assessing recurrent neoplasm. Nine patients without clinical evidence of recurrence illustrated the normal postoperative changes: a round or ovoid neopharynx connecting the base of the tongue with the cervical esophagus and intact fat planes surrounding the neopharynx, neurovascular bundles, and sternocleidomastoid muscles. In the 12 patients with recurrent neoplasm, the CT manifestations included masses involving the internal jugular lymph node chain (adjacent to the neopharynx, neurovascular bundles, or sternocleidomastoid muscles), tracheostomy site, or paratracheal region. Recurrence was mimicked on CT in two patients, one with an abscess and one with metastases from an adenocarcinoma of unknown primary site. In eight patients, a distended neopharyngeal lumen correlated with benign or malignant stricture. CT supplemented physical examination and indirect mirror examination, providing data regarding presence and extent of recurrent tumor and aiding in planning the mode and scope of therapy.