Biomedical subjects
Publications and source records attributed to J A Barakos.
To verify perineural spread of tumor along the mandibular division of the trigeminal nerve in four patients, the authors obtained cytologic specimens by means of a CT-guided transfacial fine-needle aspiration technique. Diagnoses were squamous cell carcinoma (n = 3) and meningioma (n = 1). The technique allows biopsy of deep lesions that would otherwise require open surgical biopsy.
Despite recent advances in neurodiagnostic imaging, it may be difficult to differentiate tuberculum sellae meningiomas from pituitary macroadenomas preoperatively. Magnetic resonance (MR) imaging has supplanted computed tomography as the imaging modality of choice for sellar and parasellar lesions, but unenhanced MR imaging does not reliably distinguish between all tuberculum sellae meningiomas and pituitary macroadenomas. Accurate differentiation between these alternative diagnoses of a suprasellar mass is important because a tuberculum sellae meningioma always requires a craniotomy, whereas a transsphenoidal route is preferred for removing most pituitary macroadenomas. The gadolinium-enhanced MR images of seven patients with tuberculum sellae meningioma and seven with pituitary macroadenoma were reviewed retrospectively. Although no specific radiological feature was pathognomonic, a combination of several features allowed the correct diagnosis in all cases. Three characteristics of tuberculum sellae meningiomas distinguish them from pituitary macroadenomas: 1) bright homogeneous enhancement with gadolinium, as opposed to heterogeneous, relatively poor enhancement; 2) a suprasellar rather than a sellar epicenter of tumor; and 3) tapered extension of an intracranial dural base. Each of these findings can be subtle, but careful examination of gadolinium-enhanced, high-quality, thin section coronal and sagittal MR images of the parasellar region for this constellation of findings will allow the correct preoperative diagnosis in patients with either of these tumors.
The high signal intensity of fat on T1-weighted magnetic resonance images has limited the utility of gadopentetate dimeglumine in imaging of the extracranial head and neck. Enhancing lesions may be obscured either by proximity to fat or by chemical misregistration artifact. The authors evaluated the role of a gadolinium-enhanced fat suppression imaging technique in the detection of extracranial head and neck abnormalities in 29 patients. These studies were directly compared with conventional pre- and postcontrast T1- and T2-weighted SE sequences. In detecting and defining the extent of abnormalities, fat-suppressed images were superior to non-fat-suppressed gadolinium-enhanced T1-weighted images in the majority of cases (22 of 27 [81%]). Fat-suppressed images were particularly beneficial in the detection of perineural spread of tumor as well as in defining lesions situated within or adjacent to fat-containing areas such as the base of the skull. These findings demonstrate that fat suppression techniques in combination with gadolinium enhancement are of value in extracranial head and neck imaging and should replace conventional postcontrast T1-weighted SE imaging.
The magnetic resonance (MR) imaging characteristics of lateral tibial rim (Segond) fractures and their associated injuries were reviewed in 12 patients with radiographic evidence of this fracture. Bone marrow adjacent to the fracture emitted a focally abnormal MR signal, which indicated an injury of the lateral capsular junction. The Segond fragment, however, was seen on MR images in only four of 12 patients. Associated ligamentous and meniscal injuries identified with MR imaging and arthroscopy involved the anterior (n = 11) and medial (n = 7) cruciate ligaments and the lateral (n = 4) and medial (n = 1) menisci. Focal bone marrow edema was due to injury of the lateral capsular junction. MR imaging evidence of such edema should indicate the presence of a lateral capsular injury and fracture, if one has not already been demonstrated with conventional radiography. A high association of Segond fractures with tears of the anterior cruciate ligament was confirmed, and MR imaging signs of a Segond fracture may therefore be used as indirect evidence for tears of that ligament.
The neck encloses a tremendous spectrum of tissues in a compact space. The normal and pathologic anatomy of the neck can be exquisitely displayed with high-resolution CT and MR imaging. Accurate assessment of the neck requires a thorough knowledge of both its complex anatomy and the scope of pathologic entities that may affect the various cervical compartments. We review the advances in the past year that serve to improve our ability to identify and characterize pathology of the cervical soft tissues.
Two combined magnetic resonance (MR) spin-echo pulse sequences at 0.35 T were compared with dynamic bolus contrast-enhanced computed tomography (CT) in the evaluation of focal hepatic lesions. Each combined MR sequence was performed in a separate group of patients. The first group consisted of 76 patients in whom a moderately T1-weighted sequence (spin echo [SE] 500/30 [repetition time/echo time]) was combined with a T2-weighted sequence (SE 2000/60). In the second group, consisting of 68 patients, a more heavily T1-weighted sequence (SE 250/15) was combined with the T2-weighted sequence. All studies were evaluated in a retrospective blinded fashion, with construction of receiver operating characteristic curves. We conclude that, in detection of patients with one or more focal hepatic lesions, either combined MR sequence was comparable to CT. In the detection of individual hepatic lesions, the sensitivity of the combined MR sequence with a moderately T1-weighted sequence (SE 500/30 and 2000/60) was essentially equivalent to CT (79 vs 77%, respectively). Additionally, a combined MR sequence with a heavily T1-weighted pulse sequence (SE 250/15 and 2000/60) was not statistically different than CT (86 vs 80%, respectively). These findings were supported by the receiver operating characteristic analysis.
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Magnetic resonance imaging (MRI) with ECG-gated acquisition displays the blood pool as a signal void and thereby provides high contrast differentiation between cardiovascular structures and soft-tissue masses. The role of MRI for the detection and definition of the extent of paracardiac and intracardiac masses is reviewed. The extension of mediastinal, lung, and upper abdominal tumors to the heart and pericardium is depicted favorably by MRI and this attribute is also demonstrated. It is anticipated that MRI will have an increasing role in the evaluation of primary and secondary masses of the heart and pericardium.
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Ninety patients undergoing Tc-99m disofenin hepatobiliary scintigraphy for suspected acute cholecystitis were assessed for enterogastric reflux. Seventy-seven cases showed bowel activity by one hour and were included in the study. Twenty-six percent (20/77) showed definite enterogastric reflux. The gastric activity tended to clear rapidly, even though patients remained supine during examination. Six of 20 patients (30%) with enterogastric reflux had gallbladder visualization. Of these six, one had acute cholecystitis and one had resolving acute cholecystitis with gallstone pancreatitis. There was one case each of pancreatitis, amebic abscess, sepsis, and one normal. Thus, of 20 patients with enterogastric reflux, 16 had acute cholecystitis (80%). Twenty-three of seventy-seven patients (30%) had surgically proven acute cholecystitis: of these, 16 of 23 (70% sensitivity) had gastric reflux, and 50 of 54 without acute cholecystitis did not have reflux (93% specificity). The overall accuracy of enterogastric reflux for acute cholecystitis is 86%. Gastric reflux seen on cholescintigraphy is a secondary sign of acute cholecystitis. Reflux may be related to duodenal irritation from the adjacent inflamed gallbladder.
The Kock continent ileal urinary reservoir (Kock pouch) is a new form of urinary diversion that, due to its advantages over previous techniques of urinary bypass, will probably become widespread in urologic practice. When bone imaging is performed in the presence of the Kock pouch, the unusual configuration of the pouch may obscure or simulate osseous lesions. An understanding of the surgical anatomy as well as the planar and SPECT scintigraphic appearances of the Kock pouch is necessary to avoid errors during interpretation. This series of 51 bone images reports on the variable scintigraphic appearance of the Kock pouch. In addition, the incidence and type of potentially avoidable pitfalls in the interpretation of bone imaging when this form of urinary diversion is used are evaluated.
Scintiangiography and hepatobiliary scintigraphy were performed in 45 patients with abdominal trauma. There were 18 gunshot wounds, six stab wounds, and 21 blunt injuries. Thirty-one of 45 patients showed abnormalities (69%). There were nine bilomas (4 with leaks), three leaks without biloma, (7 total leaks), five liver hematomas, three liver infarcts, one liver abscess, four renal injuries, one post-traumatic hepatic artery aneurysm, one acute acalculus cholecystitis, and four bowel injuries including one fistula, two obstructions, and one stricture. Two of the renal injuries and the hepatic artery aneurysm were identified only during scintiangiography. Eighteen of 38 gallbladders were not visualized despite normal bowel transit and delayed views to 4 hours (47%). Fourteen of 16 gallbladders were grossly normal at surgery, one had gallstones, and one had post-traumatic acalculus cholecystitis (6%). Hepatobiliary scintiangiography showed unique characteristics of vascular and renal lesions that were not seen on routine images. Sulfur colloid had no advantage over disofenin in evaluating liver injuries in nine cases. A high percentage of nonvisualized gallbladders (47%) were noted in acutely traumatized patients, and caution is recommended in diagnosing acute cholecystitis in the face of trauma.
Computed tomography (CT) is often the first imaging modality used in the diagnosis of patients with suspected abdominal disease. While it is known that early generation CT scanners often detect gallstones, the detection rate of newer equipment is not widely known. Abdominal CT scans of 226 patients who had undergone ultrasonographic (US) studies of the gallbladder were reviewed in a blinded study to determine the accuracy of state-of-the-art CT scanning equipment in the detection of cholelithiasis. Of 110 patients with US or surgical evidence of cholelithiasis, gallstones were demonstrated on CT images of 87 (79.1% sensitivity). Overall accuracy was 89.8%, while specificity was 100%. On CT images stones could appear densely (48.3%) or slightly (11.5%) calcified, as an area with a rim of increased density (21.8%), as an area of soft-tissue density (14.9%), or as an area of low density (3.4%). Stone size, stone density, section incrementation, and the pericholecystic anatomy affected the detection rate. Understanding the spectrum of findings and the other factors involved can optimize success of diagnosis of cholelithiasis on the basis of CT examinations.
We report 2 cases of diffuse intraperitoneal metastases from testicular carcinoma following transabdominal retroperitoneal lymphadenectomy. This is an unusual pattern of metastasis for nonseminomatous germ cell tumors and it is believed to be the result of direct seeding from lymphatic leakage secondary to surgery. The value of computerized tomography in diagnosing this entity is emphasized.
The Kock continent ileal urinary reservoir (Kock pouch) is a new urinary bypass system that can overcome some of the principal complications associated with other forms of urinary diversion. It is important to understand the anatomy and radiology of this new technique since radiologists play an important role in evaluating the function of the Kock pouch as well as assessing its complications. The authors review the clinical and radiographic findings in 193 patients who had undergone Kock pouch urinary diversion. Patients are evaluated radiographically in the immediate postoperative period and at regular postoperative intervals for as long as 3 years. Routine evaluation consists of Kock pouch cystography followed by intravenous urography. When indicated, computed tomography, ultrasound, and interventional radiologic procedures are used. The normal anatomy as well as the radiographic appearance of the Kock pouch is presented. In addition, the radiographic appearance of pouch complications and their frequency are reviewed.
Abdominal CT was the primary diagnostic method used to evaluate 40 patients with suspected periappendiceal abscess. Its subsequent impact on patient management was then analyzed for several categories of clinical presentation, including patients with and without a palpable right-lower-quadrant mass and postoperative patients. CT was reliable in distinguishing periappendiceal abscesses from phlegmons; 17 of 18 patients with phlegmons responded promptly to antibiotic therapy alone without need for surgery. Patients with larger, poorly localized abscesses underwent early surgical drainage. CT was successful in guiding percutaneous catheter drainage (nine patients) or aspiration (one patient) of well-localized periappendiceal abscesses in 10 of 11 patients. One attempted catheter drainage guided by sonography was technically unsuccessful. In patients without a palpable right-lower-quadrant mass, CT was helpful in establishing the diagnosis of periappendiceal inflammation. However, there were three false-positive diagnoses in patients with pericecal fluid collections including a ruptured cecal lymphoma, a ruptured cecal diverticulum, and a ruptured corpus luteum cyst. A diagnostic approach with CT is presented in patients with suspected periappendiceal abscess.
To evaluate the frequency of retroperitoneal hemorrhage related to renal biopsy, we prospectively assessed 182 patients (200 biopsies) using state-of-the-art CT and ultrasound. Our study revealed definite CT evidence of hemorrhage after 90.9% of biopsies. In a blinded analysis of images obtained in biopsied patients and in unbiopsied control patients the overall accuracy of CT was 93.8 versus 76.4% for ultrasound. Our data suggest that detectable hemorrhage is virtually always seen after renal biopsy and its frequency is much higher than noted in earlier studies.
The majority of pathologic lesions in the lung and mediastinum have relatively long T1 and T2 relaxation times and consequently yield medium to low signal intensity on T1-weighted images. Pulmonary lesions with high signal intensity on T1-weighted images are unusual and raise a special group of diagnostic considerations. In the current study, a mass with a lesion/fat signal intensity ratio of greater than 0.7 on a T1-weighted sequence was considered high signal intensity. The nature of these masses was ganglioneuroma or ganglioneuroblastoma (n = 3), atrial lipoma (lipomatous atrophy of the interatrial septum) (n = 3), pheochromocytoma (n = 2), bronchogenic cyst (n = 2), lymphangioma (n = 1), teratoma (n = 1), and a variety of primary and metastatic tumors of the mediastinum and lung. A single pathologic structure of these lesions was not present, but rather several underlying tissue compositions were noted, including fat, subacute hemorrhage, myxoid material, and cellular composition with high cytoplasmic/nuclear ratio. Thus, high signal intensity lesions of the thorax on T1-weighted images should suggest a number of differential diagnoses.