Specific Enhancement Patterns Research Articles

False Liver Metastasis by Positron Emission Tomography/Computed Tomography Scan after Chemoradiotherapy for Esophageal Cancer-Potential Overstaged Pitfalls of Treatment.

In patients with esophageal cancer undergoing neoadjuvant chemoradiotherapy (nCRT), subsequent restaging with F-18-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) can reveal the presence of interval metastases, such as liver metastases, in approximately 10% of cases. Nevertheless, it is not uncommon in clinical practice to observe focal FDG uptake in the liver that is not associated with liver metastases but rather with radiation-induced liver injury (RILI), which can result in the overstaging of the disease. Liver radiation damage is also a concern during distal esophageal cancer radiotherapy due to its proximity to the left liver lobe, typically included in the radiation field. Post-CRT, if FDG activity appears in the left or caudate liver lobes, a thorough investigation is needed to confirm or rule out distant metastases. The increased FDG uptake in liver lobes post-CRT often presents a diagnostic dilemma. Distinguishing between radiation-induced liver disease and metastasis is vital for appropriate patient management, necessitating a combination of imaging techniques and an understanding of the factors influencing the radiation response. Diagnosis involves identifying new foci of hepatic FDG avidity on PET/CT scans. Geographic regions of hypoattenuation on CT and well-demarcated regions with specific enhancement patterns on contrast-enhanced CT scans and MRI are characteristic of radiation-induced liver disease (RILD). Lack of mass effect on all three modalities (CT, MRI, PET) indicates RILD. Resolution of abnormalities on subsequent examinations also helps in diagnosing RILD. Moreover, it can also help to rule out occult metastases, thereby excluding those patients from further surgery who will not benefit from esophagectomy with curative intent.

CECT IN THE ADRENOCORTICAL CARCINOMAS: RECOGNIZING THE TYPICAL MORPHOLOGICAL FEATURES

Objectives: This study was characterization of adrenal masses on computer tomography (CT) using shape, size, and enhancement patterns. Methods: It is a retrospective study of 86 adrenal masses with morphological differences in the appearance and enhancement patterns (histopathologically proven 36 pheochromocytoma [PCCs], 26 adrenal cortical carcinoma [ACCs], one lymphoma, 22 metastases, and one schwannoma). Two experienced radiologists who were unaware of the histopathological diagnosis reviewed the computed tomography scans, morphological parameters had been noted, along with attenuations measured in Hounsfield units for all the phases of contrast-enhanced computed tomography. Results: Necrosis had been seen in all the cases of ACCs with a loss of adeniform shape. ACCs were significantly less enhancing in arterial phase and venous phase than PCC; however, no significant difference was seen with lymphomas, metastasis, and schwannoma. 25/33 (75.5%) ACC showed heterogeneous enhancement (due to the presence of necrosis) in the VP. Conclusion: Heterogenous architecture with a size of more than 5 cm is relatively specific for diagnosing ACC. No specific enhancement pattern could well differentiate ACC from lymphoma, metastases, and schwannoma.

B-Mode and Contrast Enhanced Ultrasonography Features of Gastric Inflammatory and Neoplastic Diseases in Cats.

Simple SummaryAlimentary lymphoma is the most common neoplasm of the feline gastrointestinal tract. In most cases, standard ultrasonography may not be able to discriminate between a neoplastic and inflammatory infiltrate at this level. The aim of this prospective study is to establish the value of conventional ultrasound and contrast enhanced ultrasonography in describing specific features of normal, inflammatory, and neoplastic gastric diseases in feline species. A total of 29 cats were included in the study: six healthy cats as the control group; nine with gastric inflammation; three with low-grade alimentary lymphoma; 10 with high grade alimentary lymphoma. High-grade lymphoma usually appears as a severe wall thickening with absent layer definition, regional lymphadenopathy and local steatitis on a conventional ultrasound and shows a high-contrast uptake and a homogeneous enhancement with comb teeth-like vessels on contrast-enhanced ultrasound, while gastric inflammation and low-grade alimentary lymphoma showed a large overlap on both of those two ultrasonographic techniques. Diagnostic accuracy and cut-off value were calculated and found to be relevant for thickness (3.8 mm) for inflammation vs. low-grade lymphoma and “benign” vs. “malignant” as well as peak enhancement (34.87 dB) for “benign” vs. “malignant”. Thickness and peak enhancement can be useful parameters in the characterization of gastric infiltrates in cats.Alimentary lymphoma (AL) is the most common malignancy of the feline gastrointestinal tract and may cause variable mild to severe alteration of the gastric wall on ultrasonography (US) that can be very similar to those caused by inflammation (INF). The aim of this prospective study is to establish the value of B-mode and contrast-enhanced US (CEUS) in describing specific features of normal, inflammatory, and neoplastic gastric diseases in feline species. B-mode US and CEUS of the stomach were performed in anesthetized cats with or without gastric disorders. Gastric wall qualitative and quantitative parameters were evaluated on B-mode US and CEUS examination. A total of 29 cats were included: six healthy (HEA) cats as the control group; nine INF; three low-grade lymphoma (LGAL); 10 high-grade lymphoma (HGAL). On B-mode US, there were significant differences in thickness, the wall’s layer definition and echogenicity between HGAL and all the other groups (<0.001). For CEUS, statistical differences between groups were found in the following: HGAL vs. HEA, HGAL vs. INF; HGAL vs. LGAL; INF vs. HEA. Diagnostic accuracy (AUC) and cut-off value were calculated and found to be significant for thickness (3.8 mm) for INF vs. LGAL (AUC > 0.70) and “benign” vs. “malignant” (AUC > 0.90) as well as peak enhancement (34.87 dB) for “benign” vs. “malignant” (AUC > 0.70). INF and LGAL showed an overlap of qualitative and quantitative parameters both on B-mode and CEUS, while HGAL usually appears as a severe wall thickening with absent layer definition, high-contrast uptake, a specific enhancement pattern, regional lymphadenopathy and local steatitis. Thickness and peak enhancement can be useful parameters in the characterization of gastric infiltrates in cats.

Basal Cistern Enhancement pattern in Tuberculosis Meningitis Patient on Computed Tomography Imaging: an illustrated review

Tuberculosis (TB) is one of the major worldwide threat and global burden in Indonesia. CNS tuberculosis is the most severe form of TB infection. CT evaluation on diagnosing tuberculosis meningitis (TBM) with triad of hydrocephalus, basal meningeal enhancement and infarction was reported to be sensitive. PCR cerebrospinal fluid (CSF) is known to be specific, however negative results have been reported due to presence of PCR’s inhibitors, poor lysis of mycobacteria, and the uneven distribution in specimens. CT Scan plays the vital role in diagnosing TBM patient with the presence of TBM CT triad, especially basal cistern enhancement (BME) which is the specific enhancement pattern in MTB patient. There are 9 must know BME pattern, such as contrast filling the cistern, double and triple line, linear enhancement at MCA cistern, Y sign, posterior infundibular recess enhancement, ill defined border, join the dots sign, nodular enhancement, and asymmetry off all pattern. Familiarizing BME criteria is essential to provide confident diagnosis and reduce morbidity and mortality

Diffuse-type gastric cancer: specific enhancement pattern on multiphasic contrast-enhanced computed tomography.

To evaluate the enhancement pattern of diffuse-type gastric cancers (DGCs) on multiphasic contrast-enhanced computed tomography gastrography (CECTG). We studied 21 consecutive clinically diagnosed DGC patients who underwent CECTG. Gastric distension was obtained using effervescent granules. CT images were obtained 40s (arterial phase) and 240s (delayed phase) after injection of a nonionic contrast material. Two radiologists reviewed the CT images and analyzed layers and enhancement patterns. The readers evaluated the enhancement degree (mild, moderate, or marked) and calculated CT attenuation values by placing circular regions of interest (ROIs) within each layer of the lesion. The CT findings of 11 operated cases were correlated with pathological results. Most lesions were double-layered in the arterial phase, with a moderately enhanced inner layer and a mildly enhanced outer layer, and single-layered in the delayed phase. The mean attenuation value of the inner layer (146±32.8 HU) was significantly higher than that of the outer layer (80.4±15.5 HU) in the arterial phase (p=0.0001). In the pathological analysis, wall stratification was preserved in nine cases and not preserved in two cases. Most DGCs showed a double-layered pattern in the arterial phase and a single-layered pattern with moderate enhancement in the delayed phase.

Role of US Contrast Agents in the Assessment of Indeterminate Solid and Cystic Lesions in Native and Transplant Kidneys.

Ultrasonography (US) is often the initial imaging modality employed in the evaluation of renal diseases. Despite improvements in B-mode and Doppler imaging, US still faces limitations in the assessment of focal renal masses and complex cysts as well as the microcirculation. The applications of contrast-enhanced US (CEUS) in the kidneys have dramatically increased to overcome these shortcomings with guidelines underlining their importance. This article describes microbubble contrast agents and their role in renal imaging. Microbubble contrast agents consist of a low solubility complex gas surrounded by a phospholipid shell. Microbubbles are extremely safe and well-tolerated pure intravascular agents that can be used in renal failure and obstruction, where computed tomographic (CT) and magnetic resonance (MR) imaging contrast agents may have deleterious effects. Their intravascular distribution allows for quantitative perfusion analysis of the microcirculation, diagnosis of vascular problems, and qualitative assessment of tumor vascularity and enhancement patterns. Low acoustic power real-time prolonged imaging can be performed without exposure to ionizing radiation and at lower cost than CT or MR imaging. CEUS can accurately distinguish pseudotumors from true tumors. CEUS has been shown to be more accurate than unenhanced US and rivals contrast material-enhanced CT in the diagnosis of malignancy in complex cystic renal lesions and can upstage the Bosniak category. CEUS can demonstrate specific enhancement patterns allowing the differentiation of benign and malignant solid tumors as well as focal inflammatory lesions. In conclusion, CEUS is useful in the characterization of indeterminate renal masses and cysts.

Enhancing learning during lecture note-taking using outlines and illustrative diagrams

The current study examined the effects of providing learning aids during a lecture on later test performance, and its relationship to structure-building ability. Before taking notes on an audio lecture, participants were either given a skeletal outline, an illustrative diagram, or no learning aid at all. After the lecture, participants were given a free recall test and a short-answer test that probed understanding of target concepts (requiring explanation). For low-ability structure builders, outlines improved free recall but not short-answer performance compared to the no-aid control condition. By contrast, providing high-ability structure builders with outlines improved free recall and short-answer performance (relative to the control). An illustrative diagram improved free recall and short-answer performance compared to the control condition, regardless of structure-building ability. Thus, these aids are generally useful for improving learning while listening to a lecture. Implications for the more specific enhancement patterns for low-ability structure builders are discussed.

Differentiation of tuberculosis from lymphomas in neck lymph nodes with multidetector-row computed tomography

Tuberculosis (TB) of the cervical lymph nodes may mimic lymphoma. To evaluate multidetector-row computed tomographic (MDCT) imaging criteria for differentiating between the two diseases. We retrospectively reviewed the anatomical distribution and CT enhancement patterns of the nodes in 81 patients, 27 (33%) with untreated TB and 54 (67%) with untreated lymphomas involving cervical lymph nodes. Of the patients with lymphomas, 19 (35%) had Hodgkin's disease and 35 (65%) had non-Hodgkin's lymphoma. TB predominantly involved the upper cervical nodes. The supraclavicula fossa nodes on MDCT were involved more often in Hodgkin's disease (n = 15, 79%) and non-Hodgkin's lymphoma (n = 25, 71%) than in TB (n = 3, 11%). Tuberculous lymphadenopathy commonly showed peripheral enhancement, frequently with a multilocular appearance. Peripheral enhancement was significantly more frequent in TB (n = 19, 70%) than in Hodgkin's disease (n = 1, 5%) and non-Hodgkin's lymphoma (n = 1, 3%), but homogeneous enhancement was less common in the TB group. Our findings indicate that a specific enhancement pattern of lymphadenopathy seen on MDCT was useful in differentiating between untreated TB and lymphomas of the cervical lymph nodes.

Non-invasive diagnosis of hepatocellular carcinoma ⩽2cm in cirrhosis. Diagnostic accuracy assessing fat, capsule and signal intensity at dynamic MRI

To prospectively assess the diagnostic accuracy of the incorporation of additional magnetic resonance imaging (MRI) parameters in those based on contrast enhancement pattern for the diagnosis of solitary nodules between 5 and 20mm, detected during surveillance in patients with cirrhosis. Between November 2003 and January 2010, we prospectively included 159 cirrhotic patients with a newly detected solitary nodule between 5 and 20mm in diameter by screening ultrasonography (US). Hepatic MRI and fine-needle biopsy were performed in all patients. Final diagnoses were hepatocellular carcinoma (HCC) (n=103), other malignant lesions (intrahepatic cholangiocarcinoma/metastases) (n=4), and benign lesions (n=52). The specific enhancement pattern (arterial enhancement followed by washout) yielded a sensitivity and specificity of 58.3% and 96.4%, respectively. Peritumoral capsule was present in 43 HCC and in 2 non-HCC lesions. Intralesional fat was detected in 24 nodules; 5 nodules were non-HCC. Finally, the presence of both capsule and fat was observed in 10 cases, all of them HCC (100% specificity), but all of them also displayed the specific enhancement pattern, thus adding no sensitivity or specificity. Conclusive non-invasive diagnosis of HCC in cirrhosis should be based only on the contrast enhancement pattern, while other characteristics at MRI do not increase the diagnostic accuracy.

Normal and pathological findings for the facial nerve on magnetic resonance imaging

To demonstrate the enhanced radiological anatomy and common pathological conditions of the facial nerve by using magnetic resonance imaging (MRI). A retrospective review of the MRI findings of the facial nerve of 146 patients who visited a tertiary academic referral center was conducted. The radiological anatomy of the facial nerve was well illustrated using MRI, as were most of the common pathological conditions of the facial nerve. Enhancement of the facial nerve in MRI should be correlated with the clinical data. Normal individuals can show enhancement of the tympanic or vertical segments of the facial nerve. Enhancement of the labyrinthine portion of the nerve is almost diagnostic of Bell's palsy. No specific enhancement patterns were observed for tumours or for infections of the middle or external ear. A larger population study is required for the accurate assessment of facial nerve enhancement in multiple sclerosis patients.

Tuberculosis versus non-Hodgkin’s lymphomas involving small bowel mesentery: Evaluation with contrast-enhanced computed tomography

To evaluate the specific computed tomography (CT) imaging criteria for differentiating tuberculosis involving the small bowel mesenteric lymph nodes from lymphomas. We retrospectively reviewed the anatomic distribution, CT enhancement patterns of lymphoma in 18 patients with mesenteric tuberculosis and 22 with untreated non-Hodgkin's lymphomas (NHL) involving small bowel mesentery (SBM). Of the 18 patients with tuberculosis, 9 had purely mesenteric tuberculous lymphadenopathy (TL), and 9 had mesenteric TL accompanied with tuberculous mesenteritis (TLM). CT showed that tuberculosis and NHL mainly affected lymph nodes in the body and root of SBM. Homogeneously enhanced lymph nodes in the body and root of SBM were found more often in the NHL (P < 0.05). Homogeneously mixed peripheral enhanced lymph nodes in the body of SBM were found more often in mesenteric TL and TLM (P < 0.05). Peripheral enhanced lymph nodes in the root of SBM were found more often in mesenteric TL and TLM (P < 0.01). "Sandwich sign" in the root of SBM was observed more often in NHL (P < 0.05). Anatomic lymph node distribution, sandwich sign and specific enhancement patterns of lymphadenopathy in SBM on CT images can be used in differentiating between tuberculosis and untreated NHL involving SBM.

Clinicopathological review of 46 primary retroperitoneal tumors

To clarify the clinical factors including diagnostic imaging findings that may correlate with the histopathological malignancy in primary retroperitoneal tumors. The clinical backgrounds and imaging findings of 22 benign and 24 malignant primary retroperitoneal tumors were retrospectively investigated, and the prognosis of patients with malignant retroperitoneal tumors was assessed. There were significant correlations between the presence of symptoms and malignancy (P < 0.01), as well as between the irregularity of tumor margins and malignancy (P < 0.01). On dynamic magnetic resonance imaging (MRI), 90% of malignant tumors showed early enhancement either with quick or slow washout, while 75% of benign tumors showed delayed and no enhancement (P < 0.002). All malignant and benign paraganglioma showed the same early enhancement with quick washout. Malignant lymphoma showed various enhancement patterns. The 2-year and 5-year cause-specific survival rates of the patients with malignant retroperitoneal tumors were 68.0% and 43.2%, respectively. All malignant lymphoma patients were mainly treated with chemotherapy after being diagnosed histologically. Malignant paraganglioma patients who could not meet complete resection needed chemotherapy for promising survival. The symptoms, the irregularity of the margins, and the specific enhancement pattern on the dynamic MRI may be important predictive factors of the primary malignant retroperitoneal tumors. Histological diagnosis was needed for malignant definition of paraganglioma because both benign and malignant paraganglioma showed similar clinical and imaging findings. Preoperative biopsy should be considered for selection of the appropriate treatment particularly in patients that are likely to have malignant lymphoma that could not be diagnosed definitively by the clinical and imaging findings.

DYNAMIC COMPUTED TOMOGRAPHY OF THE NORMAL FELINE HYPOPHYSIS CEREBRI (GLANDULA PITUITARIA)

The purpose of this study was to describe normal feline hypophyseal mensuration and contrast enhancement characteristics using dynamic computed tomography (CT) imaging. An intravenous bolus of an ionic iodinated contrast medium was administered to eight cats using a pressure injector while dynamic CT images were obtained every 5 s for five cats and every 7 s for three cats for a total imaging time of 5 min. Each pituitary was measured at its maximum height and width on the peak contrast medium enhancement image. A hand-drawn region of interest was placed around each hypophysis cerebri and time attenuation curves were generated. The specific enhancement pattern of the hypophysis cerebri for each cat was recorded. The mean width and height of the hypophysis cerebri was 5.2 +/- 0.4 (average +/- SD) mm and 3.1 +/- 0.3 mm, respectively. The mean time to maximum contrast enhancement was 28.6 +/- 14.8 s (range 14-50 s) from the onset of contrast medium injection. Four cats had initial dorsal and peripheral contrast enhancement patterns of the hypophysis cerebri, while four cats had an initial central contrast medium enhancement pattern. The hypophysis cerebri had a homogenous appearance in all cats, 28-50 s after contrast medium injection. The average (+/- SD) clearance half-time was 292 (+/- 87) s. Normal hypophysis cerebri mensuration and contrast medium enhancement characteristics will help in clinical evaluation of the feline hypophysis cerebri.

Tuberculosis versus lymphomas in the abdominal lymph nodes: evaluation with contrast-enhanced CT.

Tuberculosis in the abdominal lymph nodes may be difficult to distinguish from lymphomas. This study evaluated specific CT imaging criteria for differentiating these entities. We retrospectively reviewed the anatomic distribution and CT enhancement patterns of disease in 69 patients, 26 (38%) with tuberculosis and 43 (62%) with untreated lymphomas involving abdominal lymph nodes. Of the patients with tuberculosis, five (19%) had disseminated disease and 21 (81%) had nondisseminated disease. Of the patients with lymphomas, 16 (37%) had Hodgkin's disease and 27 (63%) had non-Hodgkin's lymphoma. Disseminated and nondisseminated tuberculosis involved predominantly lesser omental, mesenteric, anterior pararenal, and upper paraaortic lymph nodes. Lower paraaortic lymph nodes were involved more often in Hodgkin's disease (15 patients [94%]), non-Hodgkin's lymphoma (24 patients [89%]), and disseminated tuberculosis (five patients [100%]) than in nondisseminated tuberculosis (one patient [5%]). Mesenteric lymph nodes were involved more often in disseminated tuberculosis (four patients [80%]) and nondisseminated tuberculosis (11 patients [52%]) than in Hodgkin's disease (one patient [6%]) (p < .01). Anatomic distribution was not different between disseminated tuberculosis and non-Hodgkin's lymphoma. Tuberculous lymphadenopathy commonly showed peripheral enhancement, frequently with a multilocular appearance, whereas lymphomatous adenopathy characteristically showed homogeneous attenuation (14 patients [87.5%] with Hodgkin's disease and 19 patients [70%] with non-Hodgkin's lymphoma [p < .01]). Our findings indicate that the anatomic distribution and specific enhancement patterns of lymphadenopathy seen on contrast-enhanced CT can be useful in differentiating between tuberculosis and untreated lymphomas of the abdominal lymph nodes.

Hepatic lesion characterization in cirrhosis: significance of arterial hypervascularity on dual-phase helical CT.

Our goal was to evaluate the diagnostic significance of the presence and pattern of arterial hypervascularity in lesions detected on dual-phase helical CT in cirrhotic patients. Fifty-eight lesions greater than 1 cm in size were prospectively identified in 26 patients with end-stage liver disease who had undergone dual-phase helical CT for preoperative liver transplantation evaluation. All 26 patients had diagnoses proven by histologic evaluation or by clinical criteria. All arterial phase scans were retrospectively reviewed and lesions were categorized for the presence and pattern of arterial hypervascularity. Radiologic findings were correlated with histopathologic data. Thirty-seven of the 58 lesions had hypervascular components on arterial phase scans. All 37 of these lesions were found to represent hepatocellular carcinoma (HCC) (positive predictive value, 100%). Of the 21 remaining hypovascular lesions, 17 were HCC and four were benign (positive predictive value, 81%). Of the nine patients in whom all lesions were hypovascular, six had HCC (positive predictive value, 66%). The value of the presence of arterial hypervascularity for diagnosing HCC was statistically significant (p < .05). However, the presence or absence of arterial hypervascularity and the specific enhancement pattern revealed by helical CT did not correlate with histologic grading. The presence of hypervascularity in hepatic masses found in cirrhotic patients is highly predictive of malignancy.