Impact of reducing iodinated intravenous contrast volume in brain CT on image diagnostic quality.

PURPOSE: To investigate whether reducing the volume of intravenous iodinated contrast material injected during brain computed tomography (CT) provides reliable and accurate imaging without compromising diagnostic accuracy. METHODS: This prospective study enrolled patients undergoing enhanced brain CT at a single tertiary hospital. Subjects who agreed to participate received a reduced dose of 60 ml contrast. The images were compared to an age and gender-matched control group who received the conventional 80 cc dose. Neuroradiologists assessed image quality and interpretation using a 5-point Likert scale with six specific domains. Based on ICC, inter-rater reliability was high at 0.873. Multiple linear regression predicted overall diagnostic accuracy based on contrast dose, age, and gender. Visual Grading Characteristics (VGC) analysis was also performed to quantify regional brain enhancement differences between the two contrast groups. RESULTS: The study included 47 patients in the 60 cc group and 55 in the 80 cc control group. The results showed the 80 cc group had significantly higher enhancement ratings compared to 60 cc for all six structures assessed. The differences between groups ranged from -0.241 to -0.433 (p < 0.001) on the 5-point scale.The VGC analysis confirmed significantly greater brain parenchymal enhancement in the 80 cc group compared to the 60 cc group. CONCLUSION: The findings indicate that reducing the intravenous iodinated contrast material volume during brain CT from 80 cc to 60 cc leads to a statistically significant reduction in image quality and diagnostic accuracy. Further research with larger cohorts is needed to confirm these findings and assess the clinical impact of these differences.

Internal carotid artery dissection among younger and older patients with acute ischemic stroke.

Purpose/Aim of the study: Carotid artery dissection (CAD) is a known causative factor in the etiology of acute ischemic stroke in young patients. However, the significance of CAD in older patients with acute ischemic stroke is unclear with only a few prior clinical studies. In order to isolate the influence of CAD as an independent factor, we performed multivariate analyses of common covariables in acute ischemic stroke patients in northern Israel. MATERIALS AND METHODS: Three hundred and forty-seven consecutive patients who suffered from acute ischemic stroke had initial CT angiography (CTA) ordered from the emergency room. We reviewed the CTAs for radiologic signs of CAD, and recorded patients' demographic and clinical data from the hospital's computerized information system. RESULTS: Eighteen of the 347 patients (5.19%) had CTA evidence of CAD, with no statistically significant differences based on age, gender or ethnicity. A statistically significant inverse association between hypertension and a lower rate of CAD was found before and after stepwise logistic regression, while hyperlipidemia showed a trend toward a similar inverse association that was borderline for statistical significance. CONCLUSIONS: Our study shows that CAD is an independent and significant causative factor for acute ischemic stroke. Therefore, diagnostic imaging is indicated to rule out CAD not only in young patients, but rather in all patients with acute ischemic stroke. The inverse correlation between common vascular risk factors (i.e. hypertension and hyperlipidemia) and CAD points to CAD as an independent nonatherosclerotic causative factor in the etiology of acute ischemic stroke.

The role of computerized tomography, magnetic resonance imaging, bone scan, and monoclonal antibody nuclear scan for prognosis prediction in prostate cancer.

The single most important issue in determination of treatment options for prostate cancer is accurate assessment of disease extent. Some prediction of probability is afforded by algorithms of patient and tumor characteristics, but definitive detection of disease extension before this decision often remains difficult. This is the critical issue in the healthy 58-year-old man depicted with relatively high-grade, high-volume prostate cancer and a moderately low serum PSA relative to these characteristics. Any combination of choices for evaluation and treatment of this patient is likely to generate some controversy. This article discusses both the changing trends in treatment patterns, which place more emphasis on noninvasive staging and the limited value of conventional radiographic evaluation to detect small volume or microscopic disease. Recent advances in imaging techniques with magnetic resonance and radiolabeled monoclonal antibodies may provide more precise localization of prostate cancer in these clinical circumstances. The relative merits and limitations of the current and selected emerging imaging technology for prostate cancer detection are provided in this article.

Imaging of the umbilicus and periumbilical region.

Umbilical disorders can be classified according to embryonic remnants contained in the umbilicus, including the urachus, omphalomesenteric duct, and round ligament of the liver; the extraperitoneal paravesical spaces; the umbilical ring; and the umbilicus itself. Only one of the five types of congenital urachal abnormalities (urachal cyst) is common. All anomalies associated with the omphalomesenteric duct are rare except the Meckel diverticulum, which is the most common congenital abnormality of the gastrointestinal tract. The round ligament contains the remnant of the umbilical vein, which in the presence of portal hypertension, may open, recanalize, and form a portosystemic collateral vessel. Extraperitoneal paravesical spaces that run from the umbilicus to the bladder may contain fluid collections. The umbilical ring and the umbilicus may give rise to many masses, including omphalocele, gastroschisis, various hernias, inflammatory and suppurative processes, and neoplasms. Clinical manifestations of umbilical disorders are usually nonspecific; use of cross-sectional imaging can help identify most of these entities because of their typical locations and distributions in continuity with the urinary bladder and the umbilicus and guide therapy. Understanding the anatomy and the differential diagnosis of umbilical disorders is key to arriving at a correct diagnosis and proper patient treatment.

The superior pericardial sinus: normal appearance on gradient-echo MR images.

OBJECTIVE: The purpose of this study was to describe and explain the normal appearance of the superior pericardial sinus (the retroaortic extension of the superior pericardial recess) on gradient-recalled-echo (GRE) MR images. This is important clinically because on some GRE images the superior pericardial sinus may have a signal like that of flowing blood, which could be mistaken for an aortic dissection or an anomalous vascular structure. SUBJECTS AND METHODS: Six patients had MR imaging for evaluation of the mediastinum. In two cases, CT scans were also obtained. Both T1- and T2-weighted axial, spin-echo, ECG-gated MR images were obtained in all cases. The superior pericardial sinus was imaged with axial gradient-recalled acquisition in the steady state (GRASS) by using flip angles between 5 degrees and 60 degrees. The nature of the signal of the superior pericardial sinus on GRASS images was further studied in one patient by using spoiled GRASS (SPGR), GRASS with an inferior saturation pulse, GRASS with a slice thickness that encompassed the entire superior pericardial sinus, and cine GRASS sequences. RESULTS: The superior pericardial sinus was visualized well in all six patients. It had low signal on T1-weighted images and high signal on T2-weighted images. The signal of the sinus on T2-weighted images was heterogeneously high in three of six cases. On GRASS and cine images with flip angles less than 20 degrees, the signal of the superior pericardial sinus was similar to that of flowing blood. The sinus also had high signal on SPGR images with flip angles less than 10 degrees. No decrease in the signal of the sinus was seen on GRASS images obtained with an inferior saturation pulse. On SPGR and GRASS images obtained with the same parameters, the signals of the superior pericardial sinus were similar. When the slice thickness of the GRASS sequence was increased to encompass the entire sinus without an inferior saturation pulse, little or no decrease in signal occurred. CONCLUSION: On flow-sensitive GRE MR images obtained with a low flip angle and moderate TE, the superior pericardial sinus has high signal similar to that of flowing blood. This is a reflection of the high proton density and long T2* of pericardial fluid, and not a consequence of flow or steady-state free precession. Radiologists must be aware of this phenomenon in order to avoid misdiagnosis of aortic dissection or confusion with a vascular structure.

Staging of gynecologic malignancies using cross-sectional imaging.

Because clinical staging of gynecologic malignancies often underestimates the extent of disease, preoperative and staging work-up has routinely included cross-sectional imaging, usually CT or MR imaging. The use of ultrasound has been primarily for the evaluation of pelvic masses of unknown origin. None of these modalities has proved efficacious for screening patients for malignancy. Rather, the major indication for CT or MR imaging in this setting has been for delineating the extent of disease, and in so doing, tailoring the choice of therapy with accurate pretreatment or preoperative staging.

Cystic lymphangioma in the adult: an unusual axillary mass.

Magnetic resonance imaging (MRI) has rapidly become an effective technique for the diagnosis and localization of most musculoskeletal diseases. Because MRI lacks ionizing radiation and has superior soft tissue contrast as compared with computed tomography without the need for intravenous contrast material, MRI is emerging as the study of choice for soft tissue masses. This report describes the use of MRI in the evaluation of an unusual axillary soft tissue mass in an adult, a cystic lymphangioma.

Imaging strategies for MRI of the pelvis.

Appropriate patient triage of pelvic diseases depends upon a problem-solving approach as outlined in this article. Whether MRI is chosen as an adjunct to US or CT or as the primary modality, as in the staging of malignancy, imaging strategies for pelvic MRI can be tailored to the organ of interest and to the clinical question being asked.

MRI in staging of endometrial and cervical carcinoma.

MRI of 54 patients with endometrial and cervical carcinoma was performed on a 0.6-T superconducting magnet. In 18 of 24 cases of surgically proved endometrial carcinoma, MRI accurately showed the depth of myometrial invasion. MRI was superior to CT scan for defining the primary site and extent of the tumor in 14 of 24 cases. Of 25 patients with cervical carcinoma studied, MRI was superior to CT scan in 15 of 19 cases with CT correlation for localizing the primary site. MRI showed parametrial extension and invasion of surrounding structures but is probably less reliable than CT scan for detection of adenopathy because of false positive findings from volume averaging with bowel.

The value of MRI in evaluating perirectal and pelvic disease.

MRI of the perirectal region is facilitated by the superb soft tissue contrast, multiplanar imaging capability, lack of respiratory motion artifact and absence of clip artifact which can hamper visualization by CT scan. MRI provides distinct advantages over CT scanning without the need for ionizing radiation or the injection of intravenous contrast material. This study reviews the findings in 18 consecutive patients with a variety of perirectal pathologies including rectal carcinoma (3), gynecologic neoplasm (8), sacral lesions (2), pelvic arteriovenous malformations (2), inflammatory bowel disease (2), and a pelvic kidney (1). In the perirectal region, MR was useful to show normal tissue planes, benign processes which can mimic neoplasm, intrapelvic extension of malignancy and adenopathy.