A primer on rectal MRI in patients on watch-and-wait treatment for rectal cancer

Total neoadjuvant treatment (TNT) for rectal cancer is becoming an accepted treatment paradigm and is changing the landscape of this disease, wherein up to 50% of patients who undergo TNT are able to avoid surgery. This places new demands on the radiologist in terms of interpreting degrees of response to treatment. This primer summarizes the Watch-and-Wait approach and the role of imaging, with illustrative "atlas-like" examples as an educational guide for radiologists. We present a brief literature summary of the evolution of rectal cancer treatment, with a focus on magnetic resonance imaging (MRI) assessment of response. We also discuss recommended guidelines and standards. We outline the common TNT approach entering mainstream practice. A heuristic and algorithmic approach to MRI interpretation is also offered. To illustrate management and common scenarios, we arranged the illustrative figures as follows: (I) Clinical complete response (cCR) achieved at the immediate post-TNT "decision point" scan time; (II) cCR achieved at some point during surveillance, later than the first post-TNT MRI; (III) near clinical complete response (nCR); (IV) incomplete clinical response (iCR); (V) discordant findings between MRI and endoscopy where MRI is falsely positive, even at follow-up; (VI) discordant cases where MRI seems to be falsely positive but is proven truly positive on follow-up endoscopy; (VII) cases where MRI is falsely negative; (VIII) regrowth of tumor in the primary tumor bed; (IX) regrowth outside the primary tumor bed; and (X) challenging scenarios, i.e., mucinous cases. This primer is offered to achieve its intended goal of educating radiologists on how to interpret MRI in patients with rectal cancer undergoing treatment using a TNT-type treatment paradigm and a Watch-and-Wait approach.

Follow-up imaging of anal cancer after treatment

Anal cancer treatment response assessment can be challenging with both magnetic resonance imaging (MRI) and clinical evaluation considered essential. MRI, in particular, has shown to be useful for the assessment of treatment response, the detection of recurrent disease in follow up and surveillance, and the evaluation of possible post-treatment complications as well as complications from the tumor itself. In this review, we focus on the role of imaging, mainly MRI, in anal cancer treatment response assessment. We also describe the treatment complications that can occur, and the imaging findings associated with those complications.

Optimization of MR imaging for pretreatment evaluation of patients with endometrial and cervical cancer

Endometrial and cervical cancer are the most common gynecologic malignancies in the world. Accurate staging of cervical and endometrial cancer is essential to determine the correct treatment approach. The current International Federation of Gynecology and Obstetrics (FIGO) staging system does not include modern imaging modalities. However, magnetic resonance (MR) imaging has proved to be the most accurate noninvasive modality for staging endometrial and cervical carcinomas and often helps with risk stratification and making treatment decisions. Multiparametric MR imaging is increasingly being used to evaluate the female pelvis, an approach that combines anatomic T2-weighted imaging with functional imaging (ie, dynamic contrast material-enhanced and diffusion-weighted imaging). MR imaging helps guide treatment decisions by depicting the depth of myometrial invasion and cervical stromal involvement in patients with endometrial cancer and tumor size and parametrial invasion in those with cervical cancer. However, its accuracy for local staging depends on technique and image quality, namely thin-section high-resolution multiplanar T2-weighted imaging with simple modifications, such as double oblique T2-weighting supplemented by diffusion weighting and contrast enhancement.

Variation in positron emission tomography use after colon cancer resection

PURPOSE

Colon cancer surveillance guidelines do not routinely include positron emission tomography (PET) imaging; however, its use after surgical resection has been increasing. We evaluated the secular patterns of PET use after surgical resection of colon cancer among elderly patients and identified factors associated with its increasing use.

PATIENTS AND METHODS

We used the SEER-linked Medicare database (July 2001 through December 2009) to establish a retrospective cohort of patients age ≥ 66 years who had undergone surgical resection for colon cancer. Postoperative PET use was assessed with the test for trends. Patient, tumor, and treatment characteristics were analyzed using univariable and multivariable logistic regression analyses.

RESULTS

Of the 39,221 patients with colon cancer, 6,326 (16.1%) had undergone a PET scan within 2 years after surgery. The use rate steadily increased over time. The majority of PET scans had been performed within 2 months after surgery. Among patients who had undergone a PET scan, 3,644 (57.6%) had also undergone preoperative imaging, and 1,977 (54.3%) of these patients had undergone reimaging with PET within 2 months after surgery. Marriage, year of diagnosis, tumor stage, preoperative imaging, postoperative visit to a medical oncologist, and adjuvant chemotherapy were significantly associated with increased PET use.

CONCLUSION

PET use after colon cancer resection is steadily increasing, and further study is needed to understand the clinical value and effectiveness of PET scans and the reasons for this departure from guideline-concordant care.

MR imaging for preoperative evaluation of primary rectal cancer: practical considerations

High-resolution magnetic resonance (MR) imaging plays a pivotal role in the pretreatment assessment of primary rectal cancer. The success of this technique depends on obtaining good-quality high-resolution T2-weighted images of the primary tumor; the mesorectal fascia, peritoneal reflection, and other pelvic viscera; and superior rectal and pelvic sidewall lymph nodes. Although orthogonal axial high-resolution T2-weighted MR images are the cornerstone for the staging of primary rectal cancer, high-resolution sagittal and coronal images provide additional value, particularly in tumors that arise in a redundant tortuous rectum. Coronal high-resolution T2-weighted MR images also improve the assessment of nodal morphology, particularly for superior rectal and pelvic sidewall nodes, and of the relationship between advanced-stage tumors and adjacent pelvic structures. Rectal gel should be used in MR imaging examinations conducted for the staging of polypoid tumors, previously treated lesions, and small rectal tumors. However, it should not be used in examinations performed to stage large or low rectal tumors. Diffusion-weighted imaging is useful for identifying nodes and, occasionally, the primary tumor when the tumor is difficult to visualize with other sequences. Three-dimensional T2-weighted imaging provides multiplanar capability with a superior signal-to-noise ratio compared with two-dimensional T2-weighted imaging.

Quality initiatives: CT radiation dose reduction: how to implement change without sacrificing diagnostic quality

The risks and benefits of using computed tomography (CT) as opposed to another imaging modality to accomplish a particular clinical goal should be weighed carefully. To accurately assess radiation risks and keep radiation doses as low as reasonably achievable, radiologists must be knowledgeable about the doses delivered during various types of CT studies performed at their institutions. The authors of this article propose a process improvement approach that includes the estimation of effective radiation dose levels, formulation of dose reduction goals, modification of acquisition protocols, assessment of effects on image quality, and implementation of changes necessary to ensure quality. A first step toward developing informed radiation dose reduction goals is to become familiar with the radiation dose values and radiation-associated health risks reported in the literature. Next, to determine the baseline dose values for a CT study at a particular institution, dose data can be collected from the CT scanners, interpreted, tabulated, and graphed. CT protocols can be modified to reduce overall effective dose by using techniques such as automated exposure control and iterative reconstruction, as well as by decreasing the number of scanning phases, increasing the section thickness, and adjusting the peak voltage (kVp setting), tube current-time product (milliampere-seconds), and pitch. Last, PDSA (plan, do, study, act) cycles can be established to detect and minimize negative effects of dose reduction methods on image quality.

Dating pleistocene archeological sites by protein diagenesis in ostrich eggshell

Eggshells of the African ostrich (Struthio camelus), ubiquitous in archeological sites in Africa, have been shown by laboratory simulation experiments to retain their indigenous organic matrix residues during diagenesis far better than any other calcified tissue yet studied. The rate of L-isoleucine epimerization to D-alloisoleucine follows reversible first-order kinetics and has been calibrated for local temperature effects and used to estimate the age range of stratified archeological sites. Age estimates are consistent with radiocarbon dates from several stratified archeological sites. With adequate calibration, this technique can provide accurate ages to within 10 to 15 percent for strata deposited within the last 200,000 years in the tropics and the last 1,000,000 years in colder regions such as China.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia is an extremely rare pulmonary lesion, with only 39 cases reported in the literature. We report an additional case and review the literature. The patient is a 41-year-old man with a 5-year history of progressive dyspnea, cough, and wheezing. He was initially diagnosed as having bronchial asthma but did not respond to treatment of bronchodilators and inhaled steroids. Pulmonary function tests showed airflow obstruction. Chest computed tomography revealed a mosaic pattern of air trapping and thickening of bronchial walls. Open lung biopsy showed diffuse proliferation of pulmonary neuroendocrine cells within the bronchiolar epithelium, often bulging into or obliterating the bronchiolar lumen. These cells also breached the basement membrane, forming tumorlets. There was prominent peribronchiolar fibrosis and obliterative bronchiolitis. The pathologic evaluation of lung tissue is currently the gold standard in making a definitive diagnosis of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia, and all the reported cases were diagnosed by either open lung biopsy or lobectomy.

Mimicks of pancreatic malignancy in patients with chronic pancreatitis: correlation of computed tomography imaging features with histopathologic findings

Differentiation of chronic pancreatitis and pancreatic carcinoma can be a clinical and radiologic dilemma. Several patients with chronic pancreatitis can undergo unnecessary major abdominal surgery for benign lesions. This pictorial review illustrates the computed tomographic findings and histopathologic features of lesions mimicking pancreatic neoplasm in patients with chronic pancreatitis. Several benign lesions can simulate pancreatic malignancy in patients with chronic pancreatitis. Knowledge of the computed tomographic appearance of these benign entities is important to prevent unnecessary surgeries.

Localization of Appendix with MDCT and Influence of Findings on Choice of Appendectomy Incision

OBJECTIVE

The purpose of this study was to show the relation between McBurney's point and the appendix in patients undergoing 3D MDCT and to investigate the effect of this information on a surgeon's choice of appendectomy incision.

MATERIAL AND METHODS

Among 142 adults undergoing consecutive MDCT studies, 100 patients (35 women, 65 men; mean age, 52.1 years) with an identifiable appendix on abdominopelvic MDCT examinations were selected for the study group. The presence of intraabdominal mass or a history of abdominal surgery were the exclusion criteria. Three-dimensional reconstruction of the CT data was performed with a surface shaded display algorithm. The locations of the base of the appendix and McBurney's point were marked on a single 3D image that allowed display of the skin surface markings for each patient. The superoinferior and mediolateral distances from the level of the appendix to the level of McBurney's point were measured, and the radial distance was calculated from these measurements. A surgeon experienced in emergency abdominal surgery reviewed 3D CT images and one axial image showing the appendix, and his choice of incision for each patient based on the CT information was recorded. The influence of the superoinferior and mediolateral distances of the appendix from McBurney's point on the surgeon's decision was analyzed with a multivariate logistic regression model.

RESULTS

The appendix was exactly at McBurney's point in only 4% of the patients. In 36% of the cases, the appendix was within 3 cm, in 28% of cases it was 3-5 cm, and in 36% of the cases it was more than 5 cm away from McBurney's point. Mean +/- SD superoinferior, mediolateral, and radial distances between the appendix and McBurney's point were 33.0 +/- 24.1, 20.8 +/- 19.3, and 42.1 +/- 26.7 mm, respectively. After reviewing the images, the surgeon would have altered his incision site in 35% of the cases. The surgeon preferred a higher incision in 28% and a lower incision in 7% of the cases. Both positive and negative superoinferior displacement away from McBurney's point were significant factors regarding the surgeon's decision to alter the incision (p = 0.005), and the superoinferior distance was more than 3 cm in 94% of the cases in which the surgeon would have altered the incision.

CONCLUSION

The location of the appendix varies widely among individuals, and McBurney's point has limitations as an anatomic landmark. Three-dimensional MDCT findings can be useful to surgeons customizing appendectomy incisions. Additional information about the location of the appendix in the CT report (if possible, together with a 3D image showing the location of the appendix) may be beneficial for surgeons performing appendectomy.

Medical qualification of a commercial spaceflight participant: not your average astronaut

BACKGROUND

Candidates for commercial spaceflight may be older than the typical astronaut and more likely to have medical problems that place them at risk during flight. Since the effects of microgravity on many medical conditions are unknown, physicians have little guidance when evaluating and certifying commercial spaceflight participants. This dynamic new era in space exploration may provide important data for evaluating medical conditions, creating appropriate medical standards, and optimizing treatment alternatives for long-duration spaceflight.

CASE

A 57-yr-old spaceflight participant for an ISS mission presented with medical conditions that included moderately severe bullous emphysema, previous spontaneous pneumothorax with talc pleurodesis, a lung parenchymal mass, and ventricular and atrial ectopy. The medical evaluation required for certification was extensive and included medical studies and monitoring conducted in analogue spaceflight environments including altitude chambers, high altitude mixed-gas simulation, zero-G aircraft, and high-G centrifuge. To prevent recurrence of pneumothorax, we performed video-assisted thoracoscopic pleurodesis, and to assess lung masses, several percutaneous or direct biopsies. The candidate's 10-d mission was without incident.

CONCLUSION

Non-career astronauts applying for commercial suborbital and orbital spaceflight will, at least in the near future, challenge aerospace physicians with unknowns regarding safety during training and flight, and highlight important ethical and risk-assessment problems. The information obtained from this new group of space travelers will provide important data for the evaluation and in-flight treatment of medical problems that space programs have not yet addressed systematically, and may improve the medical preparedness of exploration-class missions.

Revisiting MRI for Appendix Location During Pregnancy

OBJECTIVE

The purpose of this study is to determine the location of the appendix in pregnant patients by MRI and to investigate the possibility of gradual upward displacement of the appendix during pregnancy.

CONCLUSION

The gradual upward displacement of the appendix during pregnancy was confirmed. MRI can be used for determination of the appendix localization in pregnant patients. Further studies with a larger number of patients will be helpful to answer this clinically relevant question.

Rapid CT diagnosis of acute appendicitis with IV contrast material

The purpose of this study was to determine the sensitivity and specificity of computed tomography (CT) without administration of oral contrast in confirming suspected acute appendicitis. One hundred seventy-three patient studies were retrieved by a computer-generated search for the word "appendicitis" in radiology reports. Patients presenting to the emergency department over an 8-month period were examined for acute abdominal pain or suspected acute appendicitis. IV-contrast-enhanced CT scans of the abdomen and pelvis were obtained without oral or rectal contrast. Criteria for diagnosis of acute appendicitis included a dilated appendix (>6 mm), periappendiceal inflammation, or abscess. Final diagnoses were established with surgical/clinical follow-up, histopathological analysis or both. The standard time (1 h) for the administration of oral contrast prior to the CT scan was eliminated. Fifty-nine CT diagnoses were made of acute appendicitis, 56 of which were histologically verified and three of which resulted in another diagnosis. One hundred fourteen CT diagnoses were negative for appendicitis. This corresponds to a sensitivity of 100% and specificity of 97%, a positive predictive value of 95%, and a negative predictive value of 100%. CT with IV contrast is sensitive and specific for the confirmation or exclusion of acute appendicitis. By eliminating the time required to administer oral contrast, the diagnosis might be made more rapidly.

Magnetic Resonance Imaging of Maternal Diseases Causing Acute Abdominal Pain During Pregnancy

Evaluation of acute abdominal pain in a pregnant patient is a clinical challenge. In these patients, magnetic resonance imaging (MRI) can allow a systematic cross-sectional evaluation of the entire abdomen and can provide clinically useful information in a short enough time for emergent diagnosis. This pictorial essay demonstrates MRI findings of various maternal diseases that can present as acute abdominal pain in pregnant patients. Familiarity with these findings is important for the radiologist to make an accurate and prompt diagnosis.

Right-Lower-Quadrant Pain and Suspected Appendicitis in Pregnant Women: Evaluation with MR Imaging—Initial Experience

PURPOSE

To determine if there is a role for magnetic resonance (MR) imaging in evaluation of pregnant women with acute right-lower-quadrant pain in whom acute appendicitis is suspected.

MATERIALS AND METHODS

Informed consent and institutional review board approval were obtained. Images obtained with a 1.5-T MR imager and medical records of 23 pregnant women (age range, 19-34 years; mean age, 24.7 years) who presented with acute right-lower-quadrant pain were retrospectively reviewed. MR protocol included use of transverse, coronal, and sagittal noncontiguous T2-weighted single-shot fast spin-echo (SE) sequences; transverse fat-suppressed T2-weighted fast SE sequences; transverse T1-weighted gradient-recalled-echo sequences; and transverse and coronal short inversion time inversion-recovery sequences performed through the lower abdomen and pelvis. MR findings were evaluated by two radiologists and compared with surgical and pathologic findings and clinical follow-up data.

RESULTS

Appendix was detected in 20 (86.9%) of 23 patients. Seven patients underwent surgery; four had acute appendicitis, and three had ovarian torsion. Two patients with pelvic abscesses not related to appendicitis underwent percutaneous drainage. Fourteen patients were treated medically. Dilated thick-walled appendix and periappendiceal inflammation were detected in three (75%) of four patients with acute appendicitis. In one patient with appendicitis, the appendix could not be visualized, but inflammation was present in the right lower quadrant. In three patients with ovarian torsion, MR imaging demonstrated right adnexal mass or inflammation. MR imaging was used to correctly identify pelvic abscesses and healthy appendix in two patients. A healthy appendix was depicted in 17 (89.5%) of 19 patients without acute appendicitis.

CONCLUSION

MR imaging shows promise for evaluation of pregnant women in whom acute appendicitis is suspected by enabling diagnosis of other possible causes of right-lower-quadrant pain, including ovarian torsion or pelvic abscesses, and demonstrating a healthy or unhealthy appendix.

Traumatic diaphragmatic rupture: can oral contrast increase CT detectability?

Traumatic diaphragmatic rupture is a frequently missed diagnosis. We present a patient with traumatic diaphragmatic hernia. Diagnosis was suggested by a emergent computed tomography (CT) examination without oral contrast. Diaphragmatic rupture and herniation of stomach were confirmed by repeating CT examination after the administration of oral contrast and using multiplanar reconstruction.

Alternative diagnoses to stone disease on unenhanced CT to investigate acute flank pain

Acute flank pain is a common problem in emergency medicine. The most frequent cause is urolithiasis, but many other entities can cause the same clinical presentation. In many institutions unenhanced computed tomography (CT) of the abdomen is used in this setting. One of the major advantages of unenhanced CT is its ability to detect other pathologies causing flank pain. In this pictorial review, we present the CT findings of pathologies other than stone disease in patients with acute flank pain.

Adrenal oncocytoma: US and CT findings

We describe a case of an oncocytoma occurring in the adrenal gland, a rare location, and describe US and CT findings of this tumor in our patient. The mass was well marginated but heterogeneous on both CT and US and unfortunately the imaging findings of the tumor are non-specific.

Transition from film to electronic media in the first-year medical school gross anatomy lab

For the benefit of the first-year gross anatomy students, we digitized and published on a Web site images that had been collected over a 30-year period. We provided a CD-ROM (compact disk, read-only media) containing the image set in higher quality format to students and faculty. We supplemented basic images with hot topics such as CT angiography, virtual colonography, computer-aided diagnosis, and 3D post-processing. Full motion video and moving JPEG (Joint Photo Expert Group) animations were integrated into the atlas. On the post course questionnaire medical students reported that the images on CD-ROM were helpful during the course and for review prior to examinations. Faculty and medical students used the CD-ROM for problem-based learning sections and facilitator training. The images were clear and easily projected during review sessions and were useful for the small group sessions, where they served as examples of normal anatomy.

Computerized tomographic colonography: performance evaluation in a retrospective multicenter setting

BACKGROUND & AIMS

No multicenter study has been reported evaluating the performance and interobserver variability of computerized tomographic colonography. The aim of this study was to assess the accuracy of computerized tomographic colonography for detecting clinically important colorectal neoplasia (polyps >or=10 mm in diameter) in a multi-institutional study.

METHODS

A retrospective study was developed from 341 patients who had computerized tomographic colonography and colonoscopy among 8 medical centers. Colonoscopy and pathology reports provided the standard. A random sample of 117 patients, stratified by criterion standard, was requested. Ninety-three patients were included (47% with polyps >or=10 mm; mean age, 62 years; 56% men; 84% white; 40% reported colorectal symptoms; 74% at increased risk for colorectal cancer). Eighteen radiologists blinded to the criterion standard interpreted computerized tomography colonography examinations, each using 2 of 3 different software display platforms.

RESULTS

The average area under the receiver operating characteristic curve for identifying patients with at least 1 lesion >or=10 mm was 0.80 (95% lower confidence bound, 0.74). The average sensitivity and specificity were 75% (95% lower confidence bound, 68%) and 73% (95% lower confidence bound, 66%), respectively. Per-polyp sensitivity was 75%. A trend was observed for better performance with more observer experience. There was no difference in performance across software display platforms.

CONCLUSIONS

Computerized tomographic colonography performance compared favorably with reported performance of fecal occult blood testing, flexible sigmoidoscopy, and barium enema. A prospective study evaluating the performance of computerized tomography colonography in a screening population is indicated.

Paleoradiology: advanced CT in the evaluation of nine Egyptian mummies

Axial thin-collimation state-of-the-art spiral computed tomography (CT) was combined with sagittal and coronal reformatting, three-dimensional (3D) reconstruction, and virtual "fly-through" techniques to nondestructively study nine Egyptian mummies. These techniques provided important paleopathologic and historical information about mummification techniques, depicted anatomy in the most informative imaging plane, illustrated the soft-tissue preservation and physical appearance of mummies in superb detail, and generated an intriguing virtual tour through hollow mummified remains without harming the specimens themselves. Images generated with these methods can help archaeologists and Egyptologists understand these fascinating members of mankind and can serve as adjunct visual aids for laypersons who are interested in mummies. CT has emerged as the imaging modality of choice for the examination of Egyptian mummies due to its noninvasive cross-sectional nature and inherently superior contrast and spatial resolution. As multi-detector row CT and postprocessing tools evolve, the capabilities and applications of CT will continue to proliferate, attesting to the expanded versatility and utility of CT as a noninvasive research tool in the multidisciplinary study of Egyptian mummies.

Development of a teaching file by using a DICOM database

A teaching file of Digital Imaging and Communications in Medicine (DICOM) images was developed. Selected computed tomographic, magnetic resonance, angiographic, nuclear medicine, and ultrasonographic images were transferred to a personal computer (PC) with a 75-GB hard drive. The database created from the DICOM header information was modified to include American College of Radiology (ACR) Learning File categories. Database modification allowed cases to be searched by diagnosis, by findings, and by patient age, sex, and demographics. Technologists inputted ACR codes into the DICOM headers before the images were acquired, thereby reducing database maintenance time. Images were manipulated and reviewed and were used for case presentations, board review, and conferences. Selected images were transferred via a hospital network to workstations for consultation, saving time for referring clinicians. The teaching file is reliable, cost-effective, and easy to install and takes advantage of recent technologic advances in computer hardware and software. Rapid cost reductions and increases in PC storage capacity allow maintenance of the teaching file in DICOM format without intermediate steps involving automation or manual conversion. This setup rivals any of the proprietary software currently available from other vendors.

CT evaluation of renovascular disease

Computed tomography (CT) plays an important role in evaluation and management of primary renovascular disease. Nonenhanced CT is useful for demonstrating renal hemorrhage, renal parenchymal or vascular calcifications, and masses. Contrast material-enhanced CT is essential to identify global or regional nephrographic abnormalities resulting from the vascular process (eg, renal infarcts, ischemia secondary to renal artery stenosis, arteriovenous communications). In addition, renal manifestations of a systemic disease (eg, vasculitis, thromboembolic disease) can be seen at CT. In trauma, occlusion of the main renal artery can be accurately diagnosed with contrast-enhanced CT. In cases of spontaneous renal hemorrhage without an apparent cause (eg, vasculitis, coagulopathy), a careful CT study should be performed to exclude renal cell carcinoma. The presence of fat in a hemorrhagic renal mass larger than 4 cm in diameter is characteristic of angiomyolipoma complicated by hemorrhage. Acute renal vein thrombosis appears as a clot in a distended renal vein, whereas renal vein retraction with collateral vessels is highly indicative of chronic thrombosis. Helical CT, especially with multiplanar two-dimensional and three-dimensional reconstruction following an intravenous injection of iodinated contrast material, has greatly improved our ability to directly image the proximal renal arteries and detect vascular lesions.

The efficacy of magnetic resonance cholangiography for the evaluation of patients with suspected choledocholithiasis before laparoscopic cholecystectomy

BACKGROUND

Endoscopic retrograde cholangiography is the most commonly utilized tool for the identification of common bile duct stones (CBDS) before laparoscopic cholecystectomy, whereas the role of magnetic resonance cholangiography (MRC) for patient evaluation before laparoscopic cholecystectomy is currently undefined.

METHODS

We prospectively evaluated the efficacy of MRC for the identification of CBDS among patients with high risk for choledocholithiasis. Patient selection was based on clinical, sonographic, and laboratory criteria. Standard cholangiograms were obtained when possible for verification of MRC results.

RESULTS

Ninety-nine patients underwent evaluation with preoperative MRC. CBDS was visualized in 30% of patients. MRC sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 85%, 90%, 77%, 94%, and 89%, respectively.

CONCLUSIONS

MRC is useful for the evaluation of patients with suspected choledocholithiasis. Advantages of MRC include its noninvasive nature, ease of application, and accuracy in identifying and estimating the size of CBDS. Application of MRC in this setting reduces the need for diagnostic endoscopic retrograde cholangiography. Future investigations should be directed at the development of cost-effective utilization strategies for MRC application.

Normal anatomy of the fetus at MR imaging

Owing to recent advances in magnetic resonance (MR) imaging, the role of obstetric MR imaging has increased in cases in which the results of ultrasonography are equivocal. Fast MR imaging sequences, such as T2-weighted fast spin-echo (SE), half-Fourier single-shot fast SE, 0.5-signal-acquired single-shot fast SE, and echo-planar imaging, have virtually eliminated the need for fetal premedication, with a concomitant improvement in image resolution and diminished blurring. Artifacts related to maternal respiratory motion and fetal motion no longer limit the anatomic detail that can be demonstrated with MR imaging. With such advances in obstetric MR imaging, knowledge of normal fetal anatomy at MR imaging is essential to detect disease in utero. MR imaging can demonstrate fetal anatomy in detail, especially the brain, thorax, abdomen, pelvis, and vasculature. Major developmental structures of the fetus, particularly the cranial nervous system, naso- and oropharynx, lungs, and major abdominal viscera, can be adequately evaluated with targeted fast MR imaging as early as the beginning of the second trimester. However, MR imaging of the heart remains limited. Fetal MR imaging during the first trimester remains controversial secondary to biosafety issues and is limited due to diminutive fetal size.

Imaging of nontraumatic hemorrhage of the adrenal gland

Nontraumatic hemorrhage of the adrenal gland is uncommon. The causes of such hemorrhage can be classified into five categories: (a) stress, (b) hemorrhagic diathesis or coagulopathy, (c) neonatal stress, (d) underlying adrenal tumors, and (e) idiopathic disease. Computed tomography (CT), ultrasonography (US), and magnetic resonance (MR) imaging play an important role in diagnosis and management. CT is the modality of choice for evaluation of adrenal hemorrhage in a patient with a history of stress or a hemorrhagic diathesis or coagulopathy (anticoagulant therapy). CT may yield the first clue to the diagnosis of adrenal insufficiency secondary to bilateral massive adrenal hemorrhage; such insufficiency is rare but life threatening. US is the modality of choice for evaluation of neonatal hematoma, and MR imaging is helpful for further characterization. MR imaging is also useful in the diagnosis of coexistent renal vein thrombosis. When an adrenal abscess is suspected, percutaneous aspiration and drainage under imaging guidance should be performed. Hemorrhage into an adrenal cyst or tumor can cause acute onset of symptoms and signs in a patient without discernible risk factors for adrenal hemorrhage. A hemorrhagic adrenal tumor should be suspected when CT or MR imaging reveals a hemorrhagic adrenal mass of heterogeneous attenuation or signal intensity that demonstrates enhancement.

Distributing digital imaging and communications in medicine data and optimizing access over satellite networks

To improve radiology access to full uncompressed Digital Imaging and Communications in Medicine (DICOM) data sets, we evaluated satellite access to a DICOM server. Radiologists' home computers were connected by satellite to a Medweb DICOM server (Medweb, San Francisco, CA). A 10.2-kb data set containing a 19-image head computed tomography (CT) scan was transferred using DirecPC (Hughes Electronics Corp, Arlington, VA) at three different times of the day; 6 AM, 3 PM, and 8 PM. The average transfer time for all 19 images from the DICOM server was 4 minutes and 17 seconds (257 seconds). The slowest transfer rate of 670 seconds (121 kbps) was obtained at 8 PM. The best transfer rate of 2 minutes, 54 seconds (467 kbps) was obtained at 6 AM. The full 16-bit DICOM images were viewed with bone, brain, and soft tissue windows. The Medweb plug-in viewer loaded the first image within 30 seconds of selecting the case for satellite transfer. In conclusion, satellite internet transfer of radiology studies is suitable for timely review of full DICOM data sets and can expand the range of teleradiology consultation.

Digital photography of digital imaging and communications in medicine-3 images from computers in the radiologist's office

To fully take advantage of the widespread use of digital imaging systems and to update and eliminate redundant steps involved in medical radiographic publication, we present our experience of processing Digital Imaging and Communications in Medicine (DICOM)-3 digital images from the point of acquisition to the point of publisher-ready radiographic images without intervening hardcopies.

Ureterolithiasis: can clinical outcome be predicted with unenhanced helical CT?

PURPOSE

To evaluate the use of helical computed tomography (CT) without contrast material enhancement for prediction of a favorable outcome in ureterolithiasis.

MATERIALS AND METHODS

CT studies were reviewed in 69 patients with a single ureteral stone not located at the ureteropelvic junction. CT findings (tissue rim sign, hydronephrosis, perinephric fat stranding, perinephric fluid collections, and thickening of renal fascia) were graded on a scale of 0-3. Stone diameter and renal parenchymal enlargement were also measured.

RESULTS

Twenty-two patients had spontaneous passage, 12 did not respond to conservative treatment, and 35 were lost to follow-up. When the latter 35 patients were excluded, perinephric fat stranding (P = .044) and perinephric fluid collections (P = .021) were graded significantly higher in patients with spontaneous stone passage. Mean stone diameter was significantly larger (P < .001) in patients in whom conservative treatment failed (mean, 7.8 mm) than in patients with spontaneous stone passage (mean, 2.9 mm). The presence of a tissue rim sign and the grade of hydronephrosis, renal fascial thickening, and renal parenchymal enlargement were not significantly different between the two groups.

CONCLUSION

In addition to stone size, the degree of perinephric fat stranding and the presence of perinephric fluid collections are useful ancillary signs for help in predicting the likelihood of stone passage.

Excretory phase CT urography for opacification of the urinary collecting system

OBJECTIVE

The purpose of our study was threefold: to evaluate the ability of excretory phase CT urography to opacify the urinary collecting system by comparing opacification seen on CT with the opacification seen on a series of unmatched IV urography examinations; to determine the optimal CT urography technique for ureteral filling by comparing studies of patients who were imaged supine, prone, and with abdominal compression; and to assess the possible value that reformatted planar images might add to axial excretory phase images.

SUBJECTS AND METHODS

Seventy patients with hematuria were imaged in one of four ways. Twenty-five patients underwent contrast-enhanced excretory phase helical CT of the kidneys, ureters, and bladder. All patients were imaged in a supine position. Ten other patients underwent a similar CT protocol in which we used abdominal compression. Ten further patients underwent excretory phase CT while in a prone position. A final 25 patients underwent IV urography. Each patient's collecting system was arbitrarily divided into 10 parts (both right and left sides of calices; pelvis; upper, mid, and lower ureters) for scoring of images on a five-point scale for opacification by contrast material. Opacification scores for the four groups of patients were then compared. For patients who underwent CT, reformatted images of the collecting systems were generated and evaluated for their potential to add value to the conventional axial images.

RESULTS

We found no significant difference in the ability of CT urography and IV urography to yield opacification of the calices, pelvis, and upper or mid ureters. Opacification of the distal ureter was less well seen on supine CT urography than on IV urography. Prone and compression CT urography resulted in better opacification of the collecting system than the supine noncompression technique. Opacification of the distal ureter was best seen with compression CT and was as good as that seen with IV urography. Reformatted CT urography was judged to be of probable or definite additional value to the axial images in 44% of cases. In each case, we saw a pathologic finding whose relationship to the kidney and collecting system was not as easy to appreciate on the axial CT scans.

CONCLUSION

CT urography with abdominal compression results in reliable opacification of the collecting system that is comparable with opacification seen on IV urography. In patients with abnormalities, reformatted images were a useful adjunct to axial images. CT urography has potential as an imaging tool for the urothelium.

Accurate determination of chemical composition of urinary calculi by spiral computerized tomography

PURPOSE

Choice of efficacious clinical management of symptomatic renal calculi can be facilitated by ascertaining the precise chemical composition of the calculus. Spiral computerized tomography (CT) is becoming a frequently used radiographic examination to establish the diagnosis and severity of calculus disease. Our objective for this study was to determine the precision of spiral CT in identifying the chemical composition of 6 different types of urinary calculi with region of interest measurements using spiral CT.

MATERIALS AND METHODS

A total of 102 chemically pure stones were separated into 6 groups. The stones along with phantoms containing butter (fat) and jello (water) were mounted vertically in the scanner gantry. Then 1 mm. thickness scanning was performed with a high speed scanner at the 2 energy levels of 80 and 120 kV. The determination of the chemical composition was performed using the absolute CT value measured at 120 kV. and the dual kilovolt CT values measured at 80 and 120 kV. Hounsfield unit at 80 kV.-Hounsfield unit at 120 kV.).

RESULTS

The absolute CT value measured at 120 kV. was able to identify precisely the chemical composition of uric acid, struvite and calcium oxalate stones. It was imprecise in differentiating calcium oxalate from brushite stone and struvite from cystine stone. However, dual kilovolt CT value was able to differentiate these latter stones with statistical significance (p < 0.03). Uric acid stones were easily differentiated from all other stones using the absolute CT value.

CONCLUSIONS

This study demonstrates that the chemical composition of urinary calculi can be accurately determined by CT scanning in an in vitro setting.

Spectrum of CT findings in nonmalignant disease of the adrenal gland

Computed tomography (CT) plays a leading role in the evaluation of nonmalignant disease of the adrenal gland. CT is highly accurate in the localization of adrenal masses in patients with diseases associated with hyperfunctioning adrenal glands such as Cushing syndrome and Cushing disease, Conn syndrome, adrenal tumors leading to virilization or feminization, and pheochromocytomas. CT permits a specific diagnosis of acute or subacute adrenal hematoma and myelolipoma. Hematomas are round to oval and have increased attenuation (50-90 HU) that decreases on follow-up CT scans. Myelolipomas typically manifest as a well-defined suprarenal mass with an attenuation of-30 to -115 HU. Adrenal cysts are usually round to oval and manifest as a hypoattenuating mass with a smooth, thin wall. CT is useful in the evaluation of patients with Addison disease, particularly the subacute form secondary to tuberculosis or disseminated histoplasmosis. Findings typically include bilateral adrenal enlargement with a central necrotic area of hypoattenuation and peripheral enhancement. Thin-section unenhanced CT permits accurate measurement of attenuation and can be used to differentiate adrenal adenoma from metastasis in a cancer patient with an indeterminate mass: Attenuation of 10 HU or less usually indicates adenoma rather than cancer. If the mass is found incidentally at contrast material-enhanced CT, delayed scans obtained as early as 5-15 minutes after intravenous administration of contrast material appear to have comparable accuracy.

Accurate determination of chemical composition of urinary calculi by spiral computerized tomography

PURPOSE

Choice of efficacious clinical management of symptomatic renal calculi can be facilitated by ascertaining the precise chemical composition of the calculus. Spiral computerized tomography (CT) is becoming a frequently used radiographic examination to establish the diagnosis and severity of calculus disease. Our objective for this study was to determine the precision of spiral CT in identifying the chemical composition of 6 different types of urinary calculi with region of interest measurements using spiral CT.

MATERIALS AND METHODS

A total of 102 chemically pure stones were separated into 6 groups. The stones along with phantoms containing butter (fat) and jello (water) were mounted vertically in the scanner gantry. Then 1 mm. thickness scanning was performed with a high speed scanner at the 2 energy levels of 80 and 120 kV. The determination of the chemical composition was performed using the absolute CT value measured at 120 kV. and the dual kilovolt CT values measured at 80 and 120 kV. Hounsfield unit at 80 kV.-Hounsfield unit at 120 kV.).

RESULTS

The absolute CT value measured at 120 kV. was able to identify precisely the chemical composition of uric acid, struvite and calcium oxalate stones. It was imprecise in differentiating calcium oxalate from brushite stone and struvite from cystine stone. However, dual kilovolt CT value was able to differentiate these latter stones with statistical significance (p < 0.03). Uric acid stones were easily differentiated from all other stones using the absolute CT value.

CONCLUSIONS

This study demonstrates that the chemical composition of urinary calculi can be accurately determined by CT scanning in an in vitro setting.

Renal inflammatory disease: the current role of CT

Computed tomography (CT) plays a significant role in establishing the diagnosis in clinically equivocal cases of renal infection, determining the extent of the disease process, and assessing its complications. Gas, calculi, renal parenchymal calcifications, hemorrhage, and masses can be revealed with unenhanced CT. A subsequent study with contrast enhancement is crucial for the complete evaluation of patients with renal infection in order to demonstrate the areas of altered nephrogram that occur as a result of the inflammatory process and to identify complications. In this article we review a spectrum of renal inflammatory disease, with illustrations of the CT findings in representative cases. We also review the role and potential pitfalls of fast scanning techniques that can image a particular phase of the nephrogram in a renal infection. In acute pyelonephritis, enhanced CT scans obtained during the cortical nephrographic phase typically demonstrate solitary or multifocal hypodense areas with obliteration of the corticomedullary differentiation. Delayed images obtained during the excretory phase are frequently more helpful in defining the extent of the disease process, identifying the complications such as renal abscess, and confirming the presence of urinary obstruction than are early images.